Glossary of anatomy terms
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# - A
Relating to the abdomen.
To move (e.g. a limb) away from the midline of the body.
The process by which digested food substances pass through the walls of some organs of the alimentary canal into the blood and lymph capillaries for circulation and use by body cells.
A neurotransmitter that carries nerve impulses across a synapse from one neuron to another or from a neuron to a muscle.
A substance (typically, a corrosive or sour-tasting liquid) with particular chemical properties including turning litmus (a testing reagent) red, neutralising alkalis, and dissolving some metals. Acidic substances have a pH less than 7. Examples include: lemon juice is a weak acid; whereas hydrochloric acid (found in the stomach) is a strong acid.
A part of the outer ear, which is the passage leading from the pinna of the outer ear, to the eardrum.
An energy-dependent process in which certain substances are able to cross cell membranes against a concentration gradient. A carrier is needed to take them across the cell membrane. Each carrier site is substance specific, so the rate of transfer is dependent on the number of carriers. One type of active transport uses the sodium-potassium pump.
Sudden, severe, short-lived disease or condition, e.g. "flu".
To move (e.g. a limb) towards the midline of the body.
The collection of lymphatic tissue at the rear of the nose. Enlargement of the adenoids from recurrent throat infections may cause obstruction to breathing through the nose.
Fibrous connective tissue, packed with masses of fat cells.
Two triangular shaped endocrine glands, each one covering the superior surface of a kidney. Each gland has a medulla and a cortex. The medulla at the centre is stimulated by the sympathetic nervous system to produce adrenaline and noradrenaline. The cortex (outer layer) is stimulated by pituitary hormones (principally ACTH) to produce corticosteroid hormones: cortisol, aldosterone, oestrogens and androgens.
A hormone secreted by the adrenal medulla. It has the function of preparing the body for ‘fright, flight or fight’ and has widespread effects on circulation, the muscles, and sugar metabolism.
A hormone synthesised and stored in the anterior pituitary gland, large amount of which are released in response to any form of stress. ACTH controls the secretion of corticosteroid hormones from the adrenal gland.
Loose connective tissue consisting of a meshwork of collagen, elastic tissue, and reticular fibres interspersed with numerous connective tissue cells.
Carries something (like a nerve impulse) toward the central part.
Small bundles of smooth muscle fibres attached to a hair follicle.
contracted the hairs stand on end, resulting in ‘goose bumps’.
A muscle primarily responsible for a movement, also called a “prime mover”.
The long passage through which food passes to be digested and absorbed. It extends from the mouth to the anus and each region is specialised for a different stage in the processing of food, absorption of food, or formation of faeces.
A compound, e.g. lime or caustic soda, with particular chemical properties including turning litmus (a testing reagent) blue and neutralising or effervescing with acids. Alkaline substances have a pH greater than 7.
Microscopic blind-ended air sacs, after the bronchioles. This is the place of gaseous exchange in the lungs. Surrounded by a capillary network, so oxygen can diffuse into the blood stream from the inhaled air and carbon dioxide can diffuse from the blood into the alveoli to be removed from the lungs during expiration. The alveoli are the place where external respiration occurs.
A part of the brain (and part of the limbic system) that is used in emotion.
An enzyme that occurs in saliva and pancreatic juice and aids the digestion of starch, which it breaks down into glucose, maltose and dextrins. Amylase will also hydrolyse glycogen to yield glucose, maltose and dextrins.
A short passage about 3.8cm long in adults and leads from the rectum to the exterior.
The body is in the upright position with the head facing forward, the arms at the sides with the palms of the hands facing forward and the feet together.
The study of how we are made, and where the different organs and parts of our body are located.
One of a group of steroid hormones, including testosterone and androsterone, that stimulate the development of male sex organs and male secondary sexual characteristics (e.g. beard growth, deepening of the voice, and muscle development). The principal source of these hormones is the testis, but they are also secreted by the adrenal cortex and ovaries in small amounts. In women excessive production of androgens gives rise to masculinisation.
A muscle that opposes the movement of a prime mover.
Relating to the front of the body.
A small fibre that connects the right and left cerebral hemispheres of the brain.
A drug (medicine) that either kills or prevents the reproduction of bacteria thus used to treat bacterial infections. N.B. They are not effective against viral or fungal infections.
Any one of a group of specialised blood proteins, synthesised in the lymphatic system, each programmed to attack a specific antigen and neutralise it.
A hormone released by the pituitary gland, which increases the reabsorption of water by the kidney, thus preventing excessive loss of water from the body. Vasopressin also causes constriction of blood vessels.
Any substance that the body regards as foreign, and produces antibodies to attack. Usually proteins – examples include bacteria or pollen.
The opening at the lower end of the alimentary canal, through which the faeces are discharged. It opens out from the anal canal, below the rectum and is guarded by tow sphincters.
The main artery of the body, from which all other derive. It arises from the left ventricle (ascending aorta), arches over the top of the heart (aortic arch) and descends in front of the backbone (descending aorta), giving off large and small branches and finally dividing to form the right and left iliac arteries. The part of the descending aorta from the aortic arch to the diaphragm is called the thoracic aorta; the part below is the abdominal aorta.
Secretes a milky fluid which when mixed with bacteria on the surface of the skin, body odour is produced. Found in the groin and armpits.
A broad, flat sheet of closely packed connective collagenous fibres; it is the connection between a muscle and its attachment.
The bones of the upper and lower extremities, includes the shoulder and pelvic girdles.
The short thin blind-ended tube, 7–10 cm long that is attached to the end of the caecum. It has no known function in man and is liable to become infected and inflamed.
One of the three membranes that protects both the brain and spinal cord. The space between the arachnoid and the pia (another membrane) is filled with cerebrospinal fluid, protecting the brain from physical blows and providing the brain with nutrients.
Prefix relating to arteries.
A blood vessel carrying blood away from the heart.
Inflammation of a joint; a general term for many specific forms of arthritis.
Prefix relating to the joints.
The smooth cartilage that caps the bones facing the synovial cavity – also called hyaline cartilage.
A fibrocartilage disk that: (1) acts as a shock absorber; (2) adjusts the uneven articulating surfaces, and; (3) allows two kinds of movements to occur simultaneously.
The meeting of two bones – a joint (the place where bones and or cartilages meet).
Any part of the cortex in which information is analysed, processed, or stored.
- Astroglia or Astrocyte A type of glial cell that supports neurons.
The first cervical vertebra, which supports the head.
The smallest particle of a chemical element.
For a body tissue or organ to waste away, especially as a result of the degeneration of cells.
Relating to the ear.
The flap of skin and cartilage that projects from the head at the exterior opening of the external auditory meatus of the ear. This is part of the outer ear.
Where body tissues destroy themselves reacting as though to foreign proteins e.g. rheumatoid arthritis.
A part of the nervous system which controls our life support systems that we don't consciously control, like breathing, digesting food, blood circulation, etc. It is sub-divided into the sympathetic and parasympathetic nervous systems.
The portion of the skeleton forming the longitudinal axis of the body – includes scull, vertebral column sternum and ribs.
Relating to the armpit. The portion of the skeleton forming the longitudinal axis of the body – includes scull, vertebral column sternum and ribs.
The second cervical vertebra, on which the atlas rests.
The long extension of a neuron that carries nerve impulses away from the body of the cell.
A synapse formed by contact between a pre-synaptic axon and a post- synaptic dendrite
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A type of micro-organism which lacking a distinct nuclear membrane. They are normally unicellular but may vary in shape. Bacteria are the only types of micro-organism that can be killed by antibiotics.
A multi-axial joint in which the globular head of one bone fits into the cuplike cavity of another, e.g. the hip joint.
Groups of hundreds of thousands of neurons at the base of the cerebrum and in the upper brainstem; they help to control well-learned movements (like walking) and sensation.
The bulging part of a muscle, between its two ends.
A tumour that neither invades surrounding tissue, nor spreads to distant sites. A disorder that causes no harmful effects.
A thick alkaline fluid secreted by the liver and stored in the gall bladder. It may be yellow, green, or brown, according to the proportions of the bile pigments (excretory products) present; other constituents are lecithin, cholesterol and bile salts. The bile salts help to emulsify fats in the duodenum so that they can be more easily digested by pancreatic lipase into fatty acids and glycerol. Bile salts also form compounds with fatty acids, which can then be transported into the lacteals. Bile also helps to stimulate peristalsis in the duodenum.
Relating to the gall bladder and its ducts.
A sac-shaped organ that has a wall of smooth muscle and stores the urine produced by the kidneys. Urine passes into the bladder through the ureters; the release of urine from the bladder is controlled by a sphincter at its junction with the urethra.
A fluid tissue that circulates throughout the body, via the arteries, capillaries and veins, providing a vehicle by which an immense variety of different substances are transported between the various organs and tissues. It is composed of blood cells suspended in a liquid medium, the plasma.
Protects the brain from chemical intrusion from the rest of the body. Blood flowing into the brain is filtered so that many harmful chemicals cannot enter the brain.
The pressure of blood against the walls of the main arteries. Highest pressure when the ventricles are contracting. Lowest pressure when the ventricles relax and refill. Adjustment to normal is by sympathetic nervous system and hormone controls.
A solid connective tissue made up of: bone cells (osteocytes) and collagen fibres, with are strengthened by inorganic salts, especially calcium and phosphate. Bone comes in two types: compact bone and spongy/cancellous bone.
Tissue filling the porous medullary cavity of the diaphysis of bones, also called myeloid tissue.
Relating to the arm.
The organ in the body that is responsible for thought, memory, sensory interpretation, movement, etc.
The base of the brain. This part of the brain connects the brain's cerebrum to the spinal cord and controls many automatic and motor functions. The brain stem is composed of the medulla oblongata, the pons, the midbrain, and the reticular formation.
The alternation of active inhalation (or inspiration) of air into the lungs through the mouth or nose with the passive exhalation (or expiration) of the air. There is a slight pause after inhalation, to allow external respiration to take place before exhalation.
- Bronchi (plural) (Bronchus is singular)
Bronchi are the air passages beyond the trachea that has cartilage and mucous glands in its wall. The trachea divides into two main (primary) bronchi: left bronchi supplying the left lung; and the right bronchi supplying the right lung. The primary bronchi subdivide into secondary bronchi, then further divisions to tertiary bronchi, to form a supply network throughout the lungs.
The air passages beyond the bronchi, and before reaching the alveoli in the lungs. Bronchioles branch many times throughout the lungs. They do not contain cartilage or mucous glands in their walls.
A process by which larger particles which cannot pass through the cell membrane are brought within the cell. The particles are engulfed by an extension of the cytoplasm (phagocytosis) which encloses them in a membrane-bound vacuole, which then combines with lysosomes, so that the particles can be digested. The reverse process where the vacuole merges with the cell membrane, releases the contents of the vacuole to outside the cell membrane.
A lateral deviation of the great toe toward the second toe, accompanied by a bursa and a callus on the bony prominence of the first metatarsal.
Flattened sacs filled with synovial fluid to help eliminate friction where a muscle rubs against another muscle, tendon or bone.
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A blind-ended pouch at the junction of the small and large intestines, situated below the ileocaecal valve. The upper end is continuous with the colon and the lower end bears the vermiform appendix.
The surgery performed to deliver a baby through an incision in the abdominal wall, when it may not be delivered vaginally.
The heel bone. This is the largest bone of the tarsus.
A hormone produced in the thyroid gland, which lowers the levels of calcium and phosphate in the blood.
Any malignant tumour. It arises from the abnormal and uncontrolled division of cells that then invade and destroy the surrounding tissues.
Small blood vessels forming networks in the tissues. The walls are one cell thick to allow exchange of nutrients, gases and waste.
The largest carpal bone of the wrist.
Relating to the heart.
Specialised muscle tissue found only in the heart.
Either of the two main arteries in the neck whose branches supply the head and neck.
One of the 8 bones forming the carpus (wrist). They are: scaphoid, lunate, triquetral, pisiform, trapezium, trapezoid, capitate and hamate.
The eight short bones connected by ligaments in each wrist.
A specialised type of connective tissue that provides support and aids movement at joints.
The bundle of nerve roots below the end of the spinal cord.
The basic unit of all living organisms, which can reproduce itself exactly. A specialised cell is a cell with a particular function, i.e. a muscle cell is quite different to a nerve cell as they have different functions, so each is specialised to its task.
The cell body of the neuron containing the nucleus.
The brain and spinal cord.
A large groove in the brain that separates the frontal and parietal lobes.
The part of the brain below the back of the cerebrum. It regulates balance, posture, movement, and muscle coordination.
The part of the ventricular system that connects the third and fourth ventricles.
The outer layer of the cerebrum composed of six cell layers of deeply folded and ridged grey matter.
One side of the cerebrum, the left or right side of the cerebrum.
A clear, watery liquid that surrounds and protects the brain and spinal cord, and is also found throughout the ventricle (brain cavities and tunnels). CSF cushions the brain and spinal cord from jolts, and circulates through the brain and the spinal canal.
The largest and most complex portion of the brain, controlling thought, learning, and many other complex activities. It is divided into the left and right cerebral hemispheres and joined by the corpus callosum, which communicates between the two hemispheres. The right side of the brain controls the left side of the body, and vice versa. Each cerebral hemisphere is divided into four lobes: the frontal lobe (responsible for reasoning, emotions, judgment, and voluntary movement); the temporal lobe (contains centres of hearing, smells, and memory); the parietal lobe (responsible for touch and spoken language ability), and the occipital lobe (responsible for centres of vision and reading ability).
Relating to the neck.
The seven small neck bones between the skull and thoracic vertebrae. The first cervical vertebra is called the atlas, and consists of a ring of bone that supports the skull by articulating with the occipital condyles. The second vertebra is called the axis and has an upward pointing process that forma a pivot on which the atlas can rotate, enabling the head to be turned. They support the head and allow it to move.
The neck of the uterus that projects into the vagina. The cervical canal passes through it, linking the cavity of the uterus with the vagina.
The layer of the eyeball between the retina and the sclera. It contains blood vessels and a pigment that absorbs excess light and so prevents blurring of vision.
Vascular structures within the ventricular system that produce cerebrospinal fluid.
Denotes long-lasting diseases, usually with gradual onset and which becomes progressively worse e.g. arthritis.
The part of the eye that connects the choroid with the iris. It has three zones: ciliary ring, ciliary processes and ciliary muscles.
A movement, in which the distal end of a bone moves in a circular path, while the proximal end remains stable, acting as a pivot, such as that achieved by the shoulder, hip, ankle or wrist joints.
The collar bone. A long slender curved bone, a pair of which forms the front part of the shoulder girdle.
In females, see the menopause. In males, the declining sexual drive and fertility, usually occurring around or after middle age.
The female counterpart of the penis, which contains erectile tissue but is not connected with the urethra. Like the penis it becomes erect under conditions of sexual stimulation, to which it is very sensitive.
These four bones are fused together to form the coccyx at the very end of the vertebral column below the sacrum. Commonly called the tailbone.
A spiral organ of the labyrinth of the inner ear. It is concerned with the reception and analysis of sound.
The protein found in the fibres of the bone, cartilage and connective tissue proper.
The main part of the large intestine, which consists of four sections – the ascending (goes up the right side of the abdomen), transverse (goes across the abdomen), descending (goes down the left side of the abdomen), and sigmoid (forms an s-shape curve in the pelvis) colons. The colon has no digestive function but it absorbs large amounts of water and electrolytes from the undigested food passed on from the small intestine. At intervals strong peristaltic movements move the dehydrated contents towards the rectum.
- Communicable Diseases A disease spread from person to person or from animal to human, e.g. measles.
The very hard and dense portion of bone.
A substance formed from two or more elements chemically united in fixed proportions, e.g. water (H2O) is a compound, as it is made up of two atoms of hydrogen (H) and one atom of oxygen (O).
A particular state of being.
Present from birth, e.g. spinal bifida.
Caught from direct contact with a sufferer - human or animal, e.g. herpes simplex (cold sores).
The ability of muscle tissue to contract.
The transparent circular part of the front of the eyeball. It refracts the light entering the eye onto the lens, which then focuses it onto the retina. The cornea contains no blood vessels and it is extremely sensitive to pain.
Relating to the crown of the head.
A large bundle of nerve fibres that connect the two cerebral hemispheres.
The glandular tissue in the ovary that forms at the site of a ruptured Graafian follicle after ovulation. It secretes the hormone progesterone, which prepares the womb for implantation. If implantation fails the corpus luteum become inactive and degenerates. If an embryo becomes implanted the corpus luteum continues to secrete progesterone until the fourth month of pregnancy, by which time the placenta has taken over the function.
The outer part of an organ, situated immediately beneath its capsule or outer membrane, e.g. adrenal cortex, renal cortex or cerebral cortex.
Andy steroid hormone synthesised by the adrenal cortex. There are two main groups of corticosteroids. The glucocorticoids (e.g. cortisol, cortisone and corticosterone) are essential for the utilisation of carbohydrate, fat and protein by the body and for a normal response to stress. Glucocorticoids have powerful anti-inflammatory effects. The mineralocorticoids (e.g. aldosterone) are necessary for the regulation of salt and water balance, thus helping to control blood pressure.
Relating to the ribs.
A pair of small glands that open into the urethra at the base of the penis. Their secretion contributes to the seminal fluid, but less than that of the prostate gland or seminal vesicles.
Relating to the skull.
12 pairs of nerves that carry information to and from sense organs, muscles and internal organs. The cranial nerves include: olfactory nerve (smell), optic nerve (sight), oculomotor nerve (eye movement, dilation of pupil), trochlear nerve (eye movement) and trigeminal nerve (sensation from the head and chewing muscles).
The top of the skull; it protects the brain. The cranium and the facial bones make up the skull.
One of the tarsal bones. The outer bone of the tarsus.
These are three bones of the tarsus, the lateral, intermediate/middle and medial, which articulate respectively with the first, second and third metatarsal bones in front and the navicular bone behind.
Prefix meaning "a bladder".
A watery fluid found inside the cell, in which the organelles are suspended.
The study of cells.
Within a body, organ, or system, e.g. the deep veins of the leg.
Due to lack of vitamins or glandular secretions, e.g. diabetes or scurvy.
When tissue or function deteriorates, more common in the elderly, e.g. osteo-arthritis.
The branching structure of a neurone that receives messages.
Movement of an elevated part of the body downward to its original position.
An area of skin whose sensory receptors contribute to each nerve.
The true skin. The layer of living tissue below the epidermis.
A thin dome-shaped muscle that separates the thoracic and abdominal cavities. The diaphragm plays an important role in breathing.
A tubular shaft of compact bone in most adult long bones.
The period of relaxation of the heart.
The passage of substances across a semi-permeable membrane to achieve equal concentrations.
The process in which the ingested food is broken down in the alimentary canal into a form that can be absorbed and assimilated by the tissues of the body. Digestion can be either: mechanical (e.g. chewing, churning and grinding food); or chemical (e.g. enzymes, bile and acid).
Finger or toe.
Want of ease; want of health; ailment. Any departure from normal health or homoeostasis. A disorder with a specific cause & recognisable signs & symptoms. Affects one part or a limited area of the body. Affects the entire body or several parts.
The displacement of bones in a joint, so that the two articulating surfaces become separated.
A disease. 11 Any failure of function.
Furthest from the trunk of the body.
A pouch or pocket in the lining of an organ (bladder, oesophagus, colon).
Relating to the back (including the back of the hand or foot).
A bundle of nerve fibres that bring information to the spinal cord.
To bend the foot upwards.
The first of the tree parts of the small intestine. It extends from the pylorus of the stomach to the jejunum. The duodenum receives vile from the gall bladder (via the common bile duct) and pancreatic juice from the pancreas. Glands in the wall of the duodenum secrete mucus, to protect the duodenum from the acidic chyme passing from the stomach.
A tough, translucent membrane that protects the brain and spinal cord.
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Secrete a watery sweat onto the surface of the skin, to help in control of body temperature. Found all over the body especially on the palms and soles.
Carrying something (like a nerve impulse) away from the central part.
There are few cells and the matrix is composed mainly of elastic fibres. It is able to extend and recoil and is found in organs and vessels where they need to stretch or change shape, e.g. lungs.
A flexible cartilage made up of yellow elastic fibres in a solid matrix. It provides support and shape to the ear-lobes (pinna), the epiglottis and part of blood vessel walls.
A graphical record of the electrical activity of the brain. Electrodes are placed on the scalp to obtain this information.
The parts of the brain that control the senses, speech, and motor functions.
Each of one of more than 100 substances, (92 of which are naturally occurring) that cannot be chemically interconverted or broken down, each consisting of atoms with a particular atomic number.
Moving a part of the body upwards along the frontal plane, e.g. elevating the scapula by shrugging the shoulders.
The process by which food substances that have been eaten but cannot be digested and absorbed are excreted from the alimentary canal as faeces by the process of defecation.
The product of conception within the uterus up to the eighth week of development, during which time all the main organs are formed.
A delicate membrane, formed o flat endothelial cells, that lines the heart and is continuous with the lining of arteries and veins. At the openings of the heart cavities it is folded back on itself to form the cusps of the valves. It presents a smooth slippery surface, which does not impede blood flow.
A gland that manufactures one or more hormones, and secretes them directly into the bloodstream, e.g. the thyroid.
The process by which bone tissue develops by replacing hyaline cartilage.
Originating within, or derived from, the body.
A series of interconnecting membranous canals in the cytoplasm. There are 2 types: rough or smooth. Synthesises lipids and steroid hormones, and is also associated with the detoxification of some drugs. Is studded with ribosomes. The site of synthesis of proteins, some of which are ‘exported’
A protein that in small amounts speeds up the rate of a biological reaction without itself being used up in the reaction (i.e. it acts as a catalyst). Enzymes are specific to the reaction they are going to catalyse.
Most superficial layer of the skin, which is itself divided into 5 layers.
Tissue that covers the external surface of the body and lines hollow structures (except blood and lymphatic vessels). Epithelial cells may be in a single layer (simple) or several layers thick (stratified) and can be classified as squamous, cuboidal or columnar, depending on their shape and function.
See under Arrector pili.
Red blood cell.
A hormone that regulates blood cell production, produced mainly in the kidneys.
A bone in the floor of the cranium that contributes to the nasal cavity and orbits.
Turning the sole of the foot to the outside.
The capacity of a nerve or muscle cell to respond to stimulus.
The act of breathing air from the lungs out through the mouth and nose.
A gland that discharges its secretion by means of a duct, which opens into an epithelial surface e.g. sweat gland.
Originating outside the body, or part of the body.
To straighten (a joint).
A straightening motion that increases the angle of a joint.
On the outside.
The fluid that surrounds the cells (i.e. it is outside the cells).
The appendages of: (1) the upper extremities – shoulders, upper arms, forearms, wrist and hands, and; (2) the lower extremities – thighs, legs, ankles feet.
The small fringe of hair on the bony ridge just above the eye. It helps to prevent moisture from running into the eye. The anatomical name is: supercillium.
One of the long stiff hairs that form a row projecting outwards from the front edge of the upper and lower eyelids. The eyelashes help keep dust away from the eye. The anatomical name is: cilium.
The protective covering of the eye. Each eye has two eyelids consisting of skin, muscle, connective tissue and sebaceous glands. Each eyelid is lined with membrane (conjunctiva) and fringed with eyelashes. Stimulation of pain receptors in the cornea causes the eyelids to close in a reflex action. The anatomical names are: blepharon, palpebra.
Relating to the face.
Some substances cannot diffuse through the semi-permeable membrane, so they can pass through it with the help of specialised protein carrier molecules.
The waste material that is eliminated through the anus. It is formed in the colon and consists of a solid or semisolid mass of undigested food remains (chiefly cellulose) mixed with bile pigments (which are responsible for the colour), bacteria, various secretions (e.g. mucus) and some water.
Either of a pair of tubes that conduct ova from the ovary to the uterus. The ovarian end opens into the abdominal cavity via a funnel-shaped structure with finger-like projections (fimbriae) surrounding the opening. Movements of the fimbriae at ovulation assist in directing the ovum to the Fallopian tube. The ovum is fertilised near the ovarian end of the tube.
A sheath of fibrous tissue enclosing skeletal muscles, holding them together.
The thigh bone, positioned between the hip and the knee. This is the longest bone in the body.
A tough cartilage in which there are dense bundles of fibres in the matrix. It is found in the invertebral discs and pubic symphysis.
This is tissue made up mainly of closely packed bundles of collagen fibres in a matrix that may contain a small number of fibrocytes.
The long thinner outer bone of the lower leg.
To bend (a joint).
A bending motion that decreases the angle of a joint.
An unborn child after the eighth week of development within the uterus.
A hormone synthesised and released by the anterior pituitary gland. FSH stimulates ripening of the follicles in the ovary and formation of sperm in the testes.
A natural opening into or through a bone, e.g. longitudinally through a vertebra.
A pathway that connects the hippocampus and the mammillary bodies.
A broken bone.
Relating to the forehead.
The bone forming the forehead and the upper parts of the orbits.
The top and front regions of each of the cerebral hemispheres. They are used for reasoning, emotions, judgment, and voluntary movement.
A simple plant that lacks the green pigment chlorophyll. Fungi include the yeasts, rusts, moulds and mushrooms. Some act as parasites on plants or animals, causing a fungal infection. Others are nutritious, e.g. some of the yeasts or mushrooms; and others may have antibacterial properties, e.g. penicillin was first derived from a mould.
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A pear-shaped sac about 7–10 cm long, lying underneath the right lobe of the liver, in which bile is stored. Bile passes (via the hepatic duct) to the gall bladder from the liver, where it is formed, and is released into the duodenum (through the common bile duct) when food is present in the duodenum.
A sex cell, either a spermatozoon, or an ovum.
A structure containing a collection of nerve cell bodies and often a number of synapses. Found in the Sympathetic and Parasympathetic Nervous System and CNS. The swellings of the posterior spinal nerve roots are termed ganglia.
Gases move from an area of high concentration to an area of low concentration, by a process of diffusion. Gases (oxygen and carbon dioxide) are exchanged with each other across a thin membrane, at the alveoli in the lungs, and at the capillaries in the body’s tissues.
Relating to the stomach.
The liquid secreted in the stomach. Its constituents are: hydrochloric acid, mucin, rennin, pepsinogen and intrinsic factor. It is involved in the digestion of protein, the absorption of vitamin B12, and it helps to kill bacteria and other organisms ingested.
The period during which a fertilised egg cell develops into a baby that is ready to be delivered. On average in humans, this is a period of 266 days (or 280 days from the first day of the last menstrual period).
Either a single cell or a collection of specialised epithelial cells that secrete substances into ducts, onto surfaces or into the blood. See exocrine and endocrine above.
Nerve cells that form a supporting network for the neurons in the brain. The word "glia" comes from the Greek word for glue.
A small biaxial joint that usually has only one axis of rotation, permitting side to side and back and forth movements, e.g. the wrist joint.
A hormone produced by the pancreas, which causes an increase in the blood sugar level and thus has an effect opposite to that of insulin.
Consists of closely folded flattened membranous sacs, found within all cells. It is involved in the storage and transport of proteins in cells.
A male or female reproductive organ, which produces the gametes, i.e. the ovary (females) and the testis (males).
Any of several hormones synthesised and released by the pituitary gland that act on the testes or ovaries (gonads) to promote production of sex hormones and either sperm or ova. The main gonadotrophins are follicle- stimulating hormone and luteinising hormone.
A mature follicle in the ovary prior to ovulation, containing a large fluid- filled cavity that distends the surface of the ovary. The oocyte develops inside the follicle, attached to one side.
Central nervous tissue that is relatively dark in colour (in contrast to white matter), due to the relatively high proportion of nerve cell bodies (and unmyelinated dendrites) present.
A hormone synthesised and stored in the anterior pituitary gland, that promotes growth of the long bones in the limbs and increases protein synthesis. Its release is controlled by the opposing actions of growth- hormone releasing factor and somatostatin. Excessive production of growth hormone results in gigantism before puberty and acromegaly in adults. Lack of growth hormone in children causes dwarfism.
These are high areas on the brain that are separated by fissures.
A carpal bone of the wrist.
The expanded, rounded surface at the proximal end of a bone.
Relating to the liver.
A protrusion of an organ or tissue outside the body cavity in which it normally lies
A condition in which the pulpy centre of an intervertebral disc protrudes through a weakened or torn surrounding outer ring. The pulpy centre pushes against a spinal nerve or even the spinal cord.
A joint that resembles the hinges on the lid of a box. The convex surface of one bone fits into the concave surface of another bone, permitting only uni-axial movement around a single axis, such as the knee joint.
A chemical mediator found in nearly all tissues. It is a mediator of inflammation and is released after skin damage. It is also involved with allergic reactions.
The study of tissues.
A physiological process by which the internal systems of the body (e.g. blood pressure, body temperature, acid-base balance) are maintained at equilibrium, despite variations in the external conditions. A state of balance and harmony.
A substance that is produced in on part of the body (by an endocrine gland), passes into the bloodstream and is carried to other distant organs or tissues, where it acts to modify their structure or function.
The bone of the upper arm. This is classed as a long-bone.
The most prevalent type of cartilage, it contains collagenous fibres and is predominantly found covering the ends of long bones, giving a smooth surface for articulation.
A strong acid present, in a very dilute form, in gastric juice.
A condition in which the diameter of the muscle fibres is increased as a result of physical activity. (The opposite of atrophy).
A region in the upper part of the brainstem that acts as a relay to the pituitary gland - it controls body temperature, circadian cycles, sleep, moods, hormonal body processes, hunger, and thirst. The hypothalamus is part of the limbic system and works with the pituitary gland.
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A disease or condition that arises spontaneously or of which the cause is not known.
A valve at the junction of the small and large intestines consisting of two membranous folds that close to prevent the backflow of food from the colon and caecum to the ileum.
The third part of the small intestine. It runs from the jejunum to the ileocaecal valve, leading to the large intestine.
A wide bone forming the upper part of each side of the pelvic bone.
The body's ability to resist infection by white blood cells and specific antibodies to each antigen.
Result of an invasion of body tissues by organisms causing disease. May result from direct or indirect contact with any of the following: (a) infected objects such as crockery or bed linen (b) people and carriers (exhibit no symptoms themselves) (c) the air (d) infected food, milk and water (e) flies, rats and other animals.
Having a known incubation period. Signs and symptoms last a certain number of days, and may cause known complications.
Lower in relation to another organ or structure.
A structure in the midbrain that is used in connection with hearing
Reaction of body tissues to injury - mechanical, chemical, or bacterial - the result of an influx of blood cells to the area. The affected area may be large or small. The signs and symptoms are: deformity, swelling, heat, redness, pain, dysfunction, tenderness.
The process by which food is taken into the alimentary canal. It involves chewing and swallowing, i.e. eating and drinking. It is also the term used for the process by which a phagocytic cell takes in solid material, such as bacteria.
Relating to the groin.
The act of breathing air into the lungs through the mouth and nose.
The bony labyrinth and the membranous labyrinth (comprising of one vestibule, one cochlea and three semi-circular canals).
The place a muscle attaches to the bone it moves.
A protein hormone produced by the pancreas by the beta cells of the islets of Langerhans, that is important for regulating the amount of sugar (glucose) in the blood. Insulin secretion is stimulated by a high concentration of blood sugar. Lack of this hormone gives rise to diabetes mellitus.
Prefix meaning "between".
Muscles that occupy the spaces between the ribs and are responsible for controlling some of the movements of the ribs. The superficial external intercostals lift the ribs during inspiration; the deep internal intercostals draw the ribs together during expiration.
See luteinising hormone.
Prefix meaning "inside" or "within".
The fluid that occurs inside a cell, in which all the organelles are suspended.
The process by which bone tissue develops directly from connective tissue.
Turning the sole of the foot inwards.
The part of the eye that regulates the amount of light that enters. It forms a coloured muscular diaphragm across the front of the lens; light enters through a central opening, the pupil. The outer margin of the iris is attached to the ciliary body.
A bone forming the lower part of each side of the pelvic bone.
A muscle contraction in which tension increases but muscle length remains the same.
A muscle contraction in which the muscle becomes shorter and thicker, but the tension remains constant.
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The second part of the small intestine, connecting the duodenum to the ileum. It comprises about two-fifth of the whole small intestine.
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Either of the pair of organs responsible for the excretion of nitrogenous wastes, principally urea, from the blood. The kidneys are situated at the back of the abdomen, below the diaphragm, on each side of the spine.
A condition in which the spine curves forward abnormally, usually at the thoracic level (hunch-backed).
A lip-shaped structure, especially either of the two pairs of skin folds that enclose the vulva. The larger outer pair is known as the labia majora and the smaller inner pair the labia minora.
The inner ear. It is a convoluted system of cavities and ducts comprising the organs of hearing and balance. The membranous labyrinth is a series of interconnected membranous canals and chambers consisting of the semi-circular canals, utricle, and saccule (concerned with balance) and the central cavity of the cochlea (concerned with hearing). It is filled with a fluid – endolymph. The bony labyrinth is the system of the bony canals and chambers that surround the membranous labyrinth. It is embedded in the petrous part of the temporal bone and is filled with fluid (perilymph).
The structures that produce and drain away fluid from the eye. The lacrimal gland secretes tears, which drain away through small openings (puncta) at the inner corner of the eye into two lacrimal canaliculi. From there the tears pass into the nasal cavity via the lacrimal sac and the nasolacrimal duct.
The smallest bone of the face. Either of a pair of rectangular bones that contribute to the orbits.
A blind-ended lymphatic vessel that extends into a villus of the small intestine. Digested fats are absorbed into the lacteals.
The organ responsible for the production of vocal sounds, also serves as an air passage conveying air from the pharynx to the lungs. It is situated in the front of the neck, above the trachea.
Relating to the outer side of the body.
White blood cells, including granulocytes, lymphocytes and monocytes.
The left half of the cerebrum - it is the centre for speech and language. In some left-handed people, however, the right hemisphere controls speech.
The transparent crystalline structure situated behind the pupil of the eye and enclosed in a thin transparent capsule. It helps to refract incoming light and focus it onto the retina.
Ligaments are fibrous bands of connective tissue linking two or more bones together.
The interconnected areas of the brain that are used in memories, emotions and some other types of behaviour.
An enzyme, produced by the pancreas and the glands of the small intestine, that breaks down fats into glycerol and fatty acids during digestion.
The largest gland of the body, situated in the top right portion of the abdominal cavity. It is divided by fissures into four lobes. Venous blood containing digested food is brought to the liver in the hepatic portal vein, whereas oxygenated blood is supplied to the liver via the hepatic artery. It has a number of functions, including: synthesis, metabolism, storage and detoxification.
An exaggerated forward curvature of the spine at the lumbar level, often seen in men with ‘beer-guts’.
Relating to the area of the back of the waist/pelvis.
The five bones of the spine situated between the thoracic vertebrae and the sacrum, in the lower part of the back. These are the largest of the unfused vertebrae.
A carpal bone of the wrist.
One of a pair of organs of respiration, situated in the chest cavity on either side of the heart. They are fibrous elastic sacs that are expanded and compressed by movements of the rib cage and diaphragm during breathing. Air enters the lungs by the two primary bronchi.
A hormone synthesised and released by the anterior pituitary gland, that stimulates ovulation, corpus luteum formation, progesterone synthesis by the ovary, and androgen synthesis by the interstitial cells of the testes. Also called: interstitial cell stimulating hormone (ICSH).
A fluid present within the vessels of the lymphatic system. It consists of the fluid that bathes the tissues, which is derived from the blood and is drained by the lymphatic vessels. It is similar in composition to plasma, but contains less protein and some cells, mainly lymphocytes.
Fine blind-ended capillaries of the lymphatic system, which join to form lymph vessels. Interstitial fluid bathing the tissues enters the lymphatic capillaries so that it can be returned to the blood stream, after being filtered by the lymphatic nodes.
One of a number of small swellings found at intervals along the lymph vessels. They are composed of lymphoid tissue and act as filters for the lymph, preventing foreign particles from entering the bloodstream; they also produce lymphocytes.
Vessels that convey lymph from the lymphatic capillaries back to the blood vessels, passing through lymph nodes on the way. They contain one- way valves to prevent back-flow of the fluid. They drain into the thoracic duct and the right lymphatic duct, which return the lymph to the bloodstream via the innominate veins.
Has a semi-solid matrix with reticulin fibres. It contains reticular cells and white blood cells. It is found in lymph nodes and organs of the lymphatic system.
They are secretory vesicles found in cells. They contain enzymes within a membrane, and are involved in the breakdown of larger molecules and fragments of organelles, to smaller substances, which may either be re- used or excreted. They are formed from the Golgi apparatus.
Refers to a tumour that is capable of invading and spreading to new tissues; cancer is a disorder that becomes life threatening if untreated.
Relating to the breasts.
The milk-producing gland in women.
The lower jawbone. A horse-shoe shaped bone bearing the lower teeth.
The wave of strong peristalsis that sweeps along the transverse colon, that occurs only about twice an hour, which forces its contents into the descending and sigmoid colons. It is often precipitated by the entry of food into the stomach.
Loosely the upper jaw. One of a pair of bones partly forming the upper jaw, the outer walls of the maxillary sinus, and the floor of the orbit. They bear the upper teeth.
Relating to the upper jaw.
To the midline of the body.
The lowest section of the brainstem (at the top end of the spinal cord); it controls automatic functions including heartbeat, breathing, swallowing, etc.
The narrow cavity inside the shaft of a long bone.
A type of cell division that produces four daughter cells, each having half the number of chromosomes of the original cell. It occurs before the formation of sperm and ova and the normal number of chromosomes is restored after fertilization.
Dark brown to black pigment in the hair, skin and the iris and choroid layer of the eyes.
A hormone secreted by the pineal gland. Melatonin secretion is controlled by daylight and its levels vary throughout any 24 hour period, usually being highest during the night and at its lowest at mid-day, its secretion also varies during different seasons of the year, as the number of daylight hours affects it. It is involved in the control of circadian and diurnal rhythms, so affects waking and sleeping. It also inhibits the growth and development of the sex organs before puberty.
A series of three protective membranes (the dura mater, the arachnoid, and the pia) that cover the brain and spinal cord.
The time in a woman’s life when the ovaries cease to produce an egg cell every four weeks and therefore menstruation ceases and the woman is no longer able to bear children. The menopause can occur at any age between the mid-thirties and mid-fifties, but most commonly between the ages of 45 – 55. There is a change in the balance of sex hormones in the body and this can lead to menopausal symptoms, such as: hot flushes, palpitations, dryness of the vagina, and possibly emotional disturbances.
The periodic sequence of events in sexually mature non-pregnant women by which and ovum is released from the ovary at four-weekly intervals. The menstrual cycle starts during puberty and ends during the menopause, it is a continuous cycle, except during pregnancy.
The discharge of blood and fragments of endometrium from the vagina at intervals of about 28 days, in women of child-bearing age.
The use of foods by the body following digestion, absorption and circulation to the body cells. Ingested foods are used both as an energy source and, after being broken down chemically during digestion, as basic materials for making complex chemical compounds required by the body.
One of the five miniature long bones constituting the palm of each hand.
One of the five miniature long bones in each foot between the ankle and toes.
A type of glial cell in the CNS.
A middle area of the brainstem that contains many important nerves (including the origins of the third and fourth cranial nerves which control eye movement and eyelid opening).
These are very small fibres that provide structural support and maintain the characteristic shape of the cell. They also permit contraction, e.g. in muscle cells.
These are contractile protein fibres which are larger than microfilaments. They are involved in the movement of: organelles within the cell; chromosomes during cell division; and cell extensions, e.g. in cilia.
The tympanic cavity and ossicles (maleus, incus and stapes).
Sausage-shaped structures found within the cytoplasm. They are involved in the cells respiration and releasing chemical energy for the cell. They are often referred to as the ‘power house’ of the cell. They are found in greater numbers in more active cells, e.g. lots are found in liver cells.
A type of cell division in which a single cell produces two genetically identical daughter cells. It is the way in which new body cells are produced for both growth and repair.
A group of atoms bonded together, representing the smallest fundamental unit of a compound that can take part in a chemical reaction.
The mound of fatty tissue lying over the pubic symphysis.
The part of both frontal lobes of the brain that control voluntary muscle movements.
Neurones responsible for movement. The cell bodies of these neurones are located within the brain or spinal cord and the axons are located in muscle fibres.
It is the first part of the digestive (alimentary system). It consists of the lips and oral cavity. It is where both mechanical digestion (by the teeth) and a small amount of chemical digestion (by salivary amylase).
This is a moist lining to the alimentary, respiratory and genitourinary tracts. The surface is made of epithelial cells some of which secrete mucus, which keeps the surface moist and can protect the surface from mechanical or chemical injury.
A viscous fluid secreted by mucous membranes. Mucus acts as a protective barrier over the membranes, a lubricant, and a carrier of enzymes. It consists chiefly of glycoproteins, particularly mucin.
The general name for a group of inherited diseases resulting in progressive weakness due to the degeneration of muscles.
A protein and phospholipid substance that covers axons and dendrites.
A sheath that surrounds and protects some nerve fibres and speeds up the process of nerve transmission.
The middle of the three layers forming the wall of the heart. It is composed of cardiac muscle and forms the greater part of the heart wall, being thicker in the ventricles than in the atria.
A form of haemoglobin found in muscle tissues.
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The cavity inside the nose that fills the space between the base of the skull and the roof of the mouth.
Either of a pair of narrow oblong bones that together forms the bridge and root of the nose.
One of the tarsal bones. A boat-shaped bone of the ankle.
Identified by new growths of tissue – either benign or malignant.
The active unit of excretion in the kidney. Blood, supplied by branches of the renal artery, is filtered through a knot of capillaries (glomerulus) into the cup-shaped Bowman’s capsule so that water, nitrogenous waste, and many other substances pass into the renal tubule. Here most of the substances are reabsorbed back into the blood, the remaining fluid (urine) passing into the collecting duct, which drains into the ureter.
Connective or supporting tissues of the nervous system.
A nerve cell. Neurones have specialised projections (dendrites and axons) and communicate with each other via an electrochemical process.
The study of the brain and the nervous system.
Chemicals that transmit nerve impulses between neurones. Some 22 neurotransmitters include acetylcholine, dopamine, endorphin, epinephrine, serotonin, and histamine.
One of the many gaps in the myelin sheath - this is where the action potential occurs along the axon.
The organ of olfaction, which also acts as an air passage that warms, moistens and filters the air on its way to the lungs.
Serious infectious diseases that must be notified to the health authorities, e.g. tuberculosis.
A spherical structure found within the nucleus. It is involved in the manufacture and assembly of ribosomes.
The largest organelle in a cell. It contains the body’s genetic material which directs all the metabolic activities of the cell. It is like the brain of the cell.
Relating to the back of the head.
A saucer-shaped bone of the skull that form the back and part of the base of the cranium.
The region at the back of each cerebral hemisphere that contains the centres of vision and reading ability.
Relating to the oesophagus.
Also called the gullet. It is a muscular tube, about 23 cm long that extends from the pharynx to the stomach. It is lined with mucous membrane, whose secretions lubricate food as it passes from the mouth to the stomach. Waves of peristalsis assist the passage of food.
One of a group of steroid hormones (including oestriol, oestrone, and oestradiol) that control female sexual development, promoting the growth and function of the female sex organs and female secondary sexual characteristics (such as breast development). Oestrogens are synthesised mainly by the ovary; small amounts are also produced by the adrenal cortex, testes and placenta. In men excessive production of oestrogen give rise to feminisation.
The first cranial nerve which is the special sensory nerve of smell. It passes nerve impulses from the olfactory receptor cells in the nasal mucosa to the olfactory area in the temporal lobe of the cerebrum where smell is perceived.
A cell in the ovary that undergoes meiosis to form an ovum.
Controls vision and the optic nerve. It is the area in the front part of the brain where the optic nerves cross one another.
Relating to the mouth.
The structures or ‘mini organs’ found within a cell, e.g. mitochondria and nucleus.
A part of the body composed of more than one tissue, which forms a structural unit responsible for a particular function (or functions). Examples are the heart, lungs, and liver.
The end of a muscle attached to a bone that does not move. 23 23
The transfer of a solvent (water) from a less concentrated solution to a more concentrated solution through a semi-permeable membrane (often the cell membrane), to equalize the concentrations on both sides of the membrane.
The three smallest bones of the body, and are in the middle ear, called the malleus, incus and stapes. They transmit sound vibrations from the outer ear to the inner ear.
A bone cell capable of synthesizing and secreting new bone matrix as needed - usually found on portions of growing bones.
A multinuclear bone-destroying cell, usually found where bone is being reabsorbed during normal growth.
A skeletal defect caused by a deficiency of vitamin D – this is the adult version of Rickets.
An inflammation of bone or bone marrow – often caused by bacteria.
Concentric cylinders of calcified bone that make up compact bone, also called “Haversian system”.
A bone disorder occurring most often in the elderly. The bones grow porous and crumble under ordinary stress.
The auricle (pinna) and the external acoustic meatus.
Two female reproductive organs situated in the lower abdomen, one on each side of the uterus. As well as producing the ova (egg), they produce the steroid hormones, oestrogen and progesterone, in response to gonadotrohpins from the anterior pituitary gland.
The process by which an ovum is released from a mature Graafian follicle. The follicle bursts open releasing the ovum, which then travels down the Fallopian tube towards the uterus. Ovulation is stimulated by the secretion of luteinising hormone by the anterior pituitary.
The mature female sex cell (gamete).
A hormone released by the pituitary gland, that causes contraction of the uterus during labour and stimulates milk flow from the breasts by causing contraction of muscle fibres in the milk ducts.
Either of a pair of approximately L-shaped bones of the face that contribute to the hard palate, the nasal cavity, and the orbits.
The study of fossil brains (from brain casts, called endocasts).
A compound gland having both endocrine and exocrine functions. It is situated behind the stomach, one end being in the curve of the duodenum and the other end at the spleen. It produces the hormones insulin and glucagon into the bloodstream to control blood sugar levels. It also produces pancreatic juices (containing enzymes for digestion) which travels via the pancreatic duct to unite with the common bile duct and empties into the duodenum at the sphincter of Oddi.
A digestive juice secreted by the exocrine part of the pancreas. It consists of: water, mineral salts, enzymes (amylase, lipase, and nucleases); 24 24 and inactive enzyme precursors (trypsinogen and chymotrypsinogen). It has an alkaline pH of 8, which partially neutralise the acidic chyme, increasing the pH of the contents of the intestine to about PH 6 to 8, which is the ideal pH for the pancreatic enzymes to be most effective.
The air-filled spaces, lined with mucous membrane, within some of the bones of the skull. They open into the nasal cavity. They comprise the frontal sinuses and the maxillary sinuses (one pair of each), the ethmoid sinuses (consisting of many spaces inside the ethmoid bone), and the two sphenoid sinuses.
A living thing that lives in (endoparasite) or on (ectoparasite) another living organism (the host). Human parasites include fungi, bacteria, viruses, protozoa, insects (e.g. head-lice or scabies) and worms.
One of the two divisions of the autonomic nervous system. The system works in balance with the sympathetic nervous system, whose actions it frequently opposes.
Two pairs of endocrine glands that are situated behind, or sometime embedded within, the thyroid gland. They are stimulated to produce parathyroid hormone by a decrease in the amount of calcium in the blood.
A hormone synthesised and released by the parathyroid glands, that controls the distribution of calcium and phosphate in the body. A high level of the hormone causes transfer of calcium from the bones to the blood; a deficiency lowers blood calcium levels, causing tetany.
Relating to the inner walls of a body cavity OR relating to the parietal bone of the skull.
Either of a pair of bones forming the top and sides of the cranium.
The middle lobe of each cerebral hemisphere between the frontal and occipital lobes; it contains important sensory centres.
Substances pass across the semi-permeable cell membrane down the concentration gradient without using energy. Types of passive transport include: diffusion, facilitated diffusion and osmosis.
The bone forming the kneecap. It is a sesamoid bone, situated in front of the knee within a tendon.
Any micro-organism (e.g. bacterium) that parasitizes and causes disease.
Arising from disease, or relating to it.
The upper limb girdle, consisting of the clavicle and scapula, also called the ‘shoulder girdle’.
Relating to the pelvis.
A pair of innominate bones formed by the fusion of the ilium, ischium and pubis. Also called the hip bones.
The paired up hip bones, formed by the ilium, ischium and pubis
The bony structure formed by the hip bones, sacrum and coccyx.
The male organ that carries the urethra, through which urine and semen are discharged. Most of the organ is composed of erectile tissue, which becomes filled with blood under conditions of sexual excitement, so that the penis is erected. In this position it can ejaculate semen. Urination 25 25 can occur in the normal hanging position.
Relating to the stomach.
One of a group of digestive enzymes that split proteins in the stomach and intestine into their constituent amino acids.
The membrane surrounding the heart. The outer fibrous pericardium completely encloses the heart and is attached to the large blood vessels emerging from the heart. The internal serous pericardium is a closed sac of serous membrane: the inner visceral portion (epicardium) is closely attached to the muscular heart wall and the outer parietal portion lines the fibrous pericardium. Within the sac is a very small amount of fluid, which prevents friction as the tow surfaces slide over one another as the heart beats.
A fibrous membrane covering the outer surfaces of bones, except at their joints. Contains bone forming cells, nerves and vessels.
The part of the nervous system that leads from the brain and spinal cord to the organs and extremities of the body.
A wavelike movement that progresses along some of the hollow tubes of the body. It occurs involuntarily and is characteristic of tubes that possess circular and longitudinal muscles, such as the intestines. It is induced by distension of the walls of the tube. Immediately behind the distension the circular muscle contracts. In front of the distension the circular muscle relaxes and the longitudinal muscle contracts which pushes the contents of the tube forward.
Oval masses of lymphoid tissue on the mucous membrane lining the small intestine.
A figure expressing acidity or alkalinity on a scale between 1 and 14, of which 7 is neutral, lower values are more acid and higher values more alkaline. Water is pH7, i.e. it is neutral.
The 14 finger bones in each hand, also the 14 toe bones in each foot.
A muscular tube, lined with mucous membrane, which extends from the beginning of the oesophagus up to the base of the skull. It is divided into the nasopharynx, oropharynx, and laryngopharynx. It acts as a passageway for food from the mouth to the oesophagus, and as an air passage from the nasal cavity and mouth to the larynx.
The study of what the different organs do and how they inter-relate with other parts of the body.
The innermost layer of the meninges. It is adjacent to the surface of the brain and the arachnoid.
A pinecone-shaped, gland-like structure located in the brain. It produces melanin and influences the onset of puberty.
A carpal bone of the wrist.
A gland attached to the base of the brain that secretes hormones.
A uni-axial joint that rotates around a central axis, e.g. base of skull and top of neck (atlas joint).
Relating to the sole of the foot. 26 26
To bend the foot towards the ground.
The outer semi-permeable membrane of a cell. All the organelles of a cell are within this membrane. It is made mainly of phospholipids and proteins.
The covering of the lungs (visceral pleura) and of the inner surface of the chest wall (parietal pleura). The covering consists of a closed sac of serous membrane, which secretes serous fluid between the layers, allowing the two layers to slide painlessly over each other during breathing. The gap between the visceral and parietal pleura is called the pleural cavity.
A network of nerves or veins.
The part of the brainstem that joins the hemispheres of the cerebellum and connects the cerebrum with the cerebellum. It is where the four pairs of cranial nerves originate: the fifth (facial sensation); the sixth (eye movement); the seventh (taste, facial expression, eyelid closure); and the eighth (hearing and balance).
Relating to the back of the knee.
Relating to the back of a body or organ.
The part of the skull that contains the brain stem and the cerebellum.
A steroid hormone secreted by the corpus luteum of the ovary, the placenta, and also (in small amounts) by the adrenal cortex and testes. It is responsible for preparing the inner lining (endometrium) of the womb for pregnancy. If fertilisation occurs it maintains the womb throughout pregnancy and prevents the further release of eggs from the ovary.
A hormone synthesised and stored in the anterior pituitary gland, that stimulates milk production after childbirth and also stimulates production of progesterone by the corpus luteum in the ovary. In both sexes excessive secretion of prolactin gives rise to abnormal production of milk (galactorrhoea).
To turn the palm down to face the floor.
The response to internal stimuli.
The process by which the contents of the alimentary tract are mixed and moved through the tract.
A male accessory sex gland that opens into the urethra just below the bladder and vas deferens. During ejaculation it secretes an alkaline fluid that forms part of the semen. The prostate may become enlarged in elderly men. This obstructs the neck of the bladder, impairing urination.
The material of which living cells are made, which includes the cytoplasm and the nucleus.
Movement forwards in the transverse plane, e.g. protraction of the shoulder girdle, as in rounding the shoulder.
Closer to the trunk than another structure.
A type of neurone that has two axons (instead of one axon and one dendrite). One axon is oriented towards the spinal cord; the other axon is oriented toward either skin or muscle. 27 27
The time at which the onset of sexual maturity occurs and the reproductive organs become functional. In both sexes this is manifested by the appearance of secondary sexual characteristics, and in girls by the start of menstruation. These changes are brought about by an increase in sex hormone activity.
A bone forming the lower and anterior part of each side of the pelvic bone. They meet at the front at the pubic symphysis.
Relating to, associated with, or affecting the lungs.
The artery that conveys blood from the heart to the lungs. It is the only artery in the body containing deoxygenated blood.
The artery carrying blood from the lungs to the heart. It is the only vein in the body carrying oxygenated blood.
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The outer and shorter bone of the forearm. This is classed as a long- bone.
A slightly dilated section of the large intestine, about 13cm long. It leads from the sigmoid colon to the anal canal. Faeces are stored in the rectum before defecation.
An automatic or involuntary action without the necessary involvement of consciousness. A simple reflex arc involves a message from a sensory nerve to the spinal cord, which crosses a synapse on the grey matter of the cord via an interneurone, and sends a message out to the relevant motor nerve.
Relating to the kidneys.
The process of gaseous exchange between an organism and its environments. External respiration occurs in the lungs, and internal respiration occurs at the bodies tissues.
A network of nerve cells in the brainstem that are involved in maintaining sleep or wakefulness.
The light-sensitive layer that lines the interior of the eye. The outer part of the retina, next to the choroid, is pigmented to prevent the passage of light. The inner part, next to the cavity of the eyeball, contains rods and cones (light-sensitive cells) and their associated nerve fibres. A large number of cones are concentrated in a depression in the retina at the back of the eyeball called the fovea.
Movement backwards in the transverse plane, as in bracing the shoulder girdle back, military style.
They are composed of RNA and proteins. They are found within the cytoplasm either free, or attached to rough endoplasmic reticulum. They synthesise proteins from amino acids.
There are 12 pairs of ribs which form part of the skeleton of the thorax. They protect the heart and the lungs. All 12 pairs articulate with one of the 12 thoracic vertebrae at the back; the first 7 (called the true-ribs) articulate with the sternum at the front; the next 3 pairs are linked by cartilage to the rib above and are called false ribs; the last 2 ribs are called floating ribs and they end freely in the muscles of the body wall. 28 28
A childhood disease caused by a deficiency of vitamin D – progresses to skeletal deformity.
The right half of the cerebrum - it processes visual information.
To move a bone around its longitudinal axis e.g. the atlas moving on the axis in the neck.
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A multi-axial joint in which opposing articular surfaces are shaped like a saddle, e.g. base of thumb.
The five vertebrae that are fused together to form the sacrum. Positioned in the pelvic area, below the lumbar vertebrae and above the coccyx.
A thin membrane enclosing each muscle fibre.
The alkaline liquid secreted by the salivary glands and the mucous membrane of the mouth. Its principal constituents are water, mucus, buffers, and enzymes (e.g. amylase). The functions of saliva are to keep the mouth moist, to aid swallowing of food, to minimise changes of acidity in the mouth, and to digest starch.
A gland that produces saliva. There are three pairs of salivary glands: the parotid glands, the sublingual glands, and submandibular glands. They are stimulated by reflex action, which can be initiated by the taste, smell, sight, or thought of food.
One of the carpal bones. A boat shaped bone of the wrist.
The shoulder blade. A triangular bone, a pair of which forms the back part of the shoulder girdle.
Cells that produce myelin.
The white fibrous outer layer of the eyeball. At the front of the eye it becomes the cornea.
An abnormal lateral curvature of the spine in the thoracic or lumbar region.
The paired sac that holds the testes and epididymides outside the abdominal cavity. Its function is to allow the production and storage of spermatozoa to occur at a lower temperature than that of the abdomen. Further temperature control is achieved by contraction or relaxation of muscles in the scrotum.
Found in the dermis of the skin and open into the hair follicle. They produce an oily substance called sebum. Most numerous in hairy parts of the body. They are absent on palms, soles and lips.
An oily secretion of the sebaceous gland. It acts to lubricate the hair shaft and moisturise the skin. Sebum combined with sweat forms the protective acid mantle on the surface of the skin.
Occurs as a consequence of an original condition, e.g. pneumonia after measles.
Three tubes that form part of the membranous labyrinth of the inner ear. They are concerned with balance and each canal registers movement in a different plane.
Either of a pair of male accessory sex glands that open into the vas 29 29 deferens before it joins the urethra. The seminal vesicles secrete most of the liquid component of semen.
Any part of the brain that receives messages from a sense organ (like the eyes, nose, tongue, or ears) or messages of touch and temperature from anywhere in the body.
An afferent nerve cell that carries sensory information (like sound, touch, taste, smell, or sight) to the Central Nervous System.
There are several types of sensory receptors (specialised nerve endings in the skin that can detect touch, temperature, pressure and pain, and they are widely distributed in the dermis. Free nerve endings in the skin detect pain; Meissner’s corpuscles detect light pressure; and Pacinian corpuscles detect deep pressure, in the skin.
An oval nodule of bone formed within a tendon and sliding over another bony surface e.g. the kneecap (patella).
A chemical present in platelets, the brain, and the intestinal wall. It causes intestinal secretions, contraction of smooth muscle and is involved in blood clotting.
A smooth transparent membrane, consisting of a double layer of loose areolar connective tissue lined by simple squamous epithelium. A watery serous fluid is secreted between the layers to allow frictionless movement of an organ the membranes surround. An example is the pleura surrounding the lungs and lining the thoracic cavity is made of serous membrane.
Hard to endure, rigorous, unsparing.
Any steroid hormone produced mainly by the ovaries or testes (but also in smaller amounts in the adrenal cortex), that is responsible for controlling sexual development and reproductive function. Oestrogens and progesterone are the female sex hormones; androgens are the male sex hormones.
Something you can see as an indication of a problem e.g. redness.
It is the muscle attached to the bones of the skeleton and is involved in movement. It is also called striated or voluntary muscle, as it is under conscious control.
The bones that comprise the head and face.
Also called non-striated, or visceral, or involuntary muscle. It is found in the walls of hollow organs, e.g. bladder, blood vessels. It is not under voluntary control.
This is a type of active transport that maintains the unequal concentrations of sodium and potassium ions on either side of the plasma membrane. The process maintains the cells membrane potential, which is required in certain cells, e.g. for the transmission of nerve impulses. This process requires a lot of energy.
- Somatosensory cortex An area of the sensory cortex in the parietal lobes that receives messages of touch, temperature, and certain other bodily sensations.
See growth hormone.
A mature male sex cell (gamete). The tail of a sperm enables it to swim, which is important as a means for reaching and fertilising the ovum.
A bone forming the base of the cranium behind the eyes.
A circular muscle that helps keep a circular structure open and/or closed, e.g. lips, anus.
A thick bundle of nerve fibres that runs from the base of the brain to the hip area, travelling through the vertebral column.
A sharp elongated process of a bone, such as the spine of a vertebra.
A large dark-red ovoid organ situated on the left side of the body below and behind the stomach. Contains lymphoid tissue within a meshwork of reticular fibres packed with red blood cells.
Relating to the spleen.
Commonly called the breast-bone. It is a flat bone, 15 – 20 cm long, extending from the base of the neck to just below the diaphragm and forming part of the thorax. It articulates with the clavicles and the first seven pairs of ribs.
A distensible saclike organ that forms part of the alimentary canal between the oesophagus and the duodenum. The stomach lies just below the diaphragm, to the right of the spleen and partly under the liver. Its function is to continue the process of digestion that begins in the mouth. It secretes gastric juice to contribute to chemical digestion, which together with the churning action of the muscular layers of the stomach – reduces the food to a semiliquid partly digested mass (chyme) that passes on to the duodenum.
The first and outermost layer of the epidermis of the skin. Composed of flattened dead cells which are constantly being shed.
- Stratum germinativum The fifth or basal layer of the epidermis. This is the final layer of the epidermis and is in contact with the dermis. The cells here obtain nutrition from the blood supply to the dermis. This is the primary site of cell division in the skin.
The third or granular layer of the epidermis. Keratin begins to form in these cells which contain granules and the cells in this layer are dying.
The clear or second layer of the epidermis. The cells here are only a few layers deep. The layer has a translucent appearance and acts as a barrier, helping water-proof the skin.
The fourth or prickle cell layer of the epidermis. The cells are prickly in appearance and are still living. Some cell reproduction may occur in areas of friction, e.g. soles of the feet.
Prefix meaning "under".
A disease that progresses more rapidly than a chronic one, but does not become acute.
On or near the surface.
Above; the upper of two parts.
To turn the palm up. 31 31
The area of the hypothalamus that controls circadian rhythms, (day and night cycles and the biological clock) and reproduction cycles.
One of the two divisions of the autonomic nervous system. The system works in balance with the parasympathetic nervous system, whose actions it frequently opposes.
A cartilaginous joint in which two bony surfaces are covered by thin layers of hyaline cartilage and cushioned by fibrocartilaginous discs, e.g. vertebrae or pubic symphysis. Also the line that marks the fusion of 2 bones that where separate in early childhood.
Something the “patient” complains of as an indication of a problem, e.g. pain.
A minute gap across which nerve impulses pass from one neurone to the next, at the end of a nerve fibre. The word "synapse" was coined by Sir Charles Scott Sherrington in 1897.
The space between two articulating bones.
The thick colourless lubricating fluid that surrounds a joint or a bursa and fills a tendon sheath. It is secreted by the synovial membrane.
An articulated joint in the skeleton where synovial fluid is found between the bones of the joint. This nourishes and lubricates the joints.
It consists of areolar connective tissue and elastic fibres and it lines the cavities of moveable joints. It secretes a clear, sticky, oily fluid called synovial fluid.
A group of organs and tissues associated with a particular physiological function, such as the nervous system or respiratory system.
The period of contraction of the heart.
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The sense of touch.
One of the tarsal bones. This is the ankle bone.
One of the seven bones forming the tarsus (ankle) and part of the foot. They are: talus, calcaneus, navicular, cuneiform (medial, intermedial and lateral) and cuboid bones.
Sensory receptors concerned with the sense of taste and are located in the epithelium covering the surface of the tongue. Some taste buds are also present in the soft palate, the epiglottis and parts of the pharynx. Different taste buds detect: sweet; salty; sour; and bitter.
The fluid secreted by the lacrimal glands to keep the front of the eyeball moist and clean. Tears contain lysosyme, an enzyme, which destroys bacterial. Irritation of the eye, and sometimes emotion, cause excessive production of tears.
The dorsal (top) portion of the midbrain (mesencephalon).
One of the hard structures in the mouth used for cutting and chewing food. There are four different types of tooth: canine, incisor, premolar and molar.
Ventral (bottom) part of the midbrain (mesencephalon).
Either of a pair of bones of the cranium, forming part of the side of the cranium and part of the base of the skull and contains the middle and 32 32 inner ears.
The region at the lower side of each cerebral hemisphere; contains centres of hearing and memory.
A strong cord of collagenous fibres that attaches a muscle to the periosteum of a bone.
Either of the pair of male sex organs within the scrotum. They produce spermatozoa, and secrete the male sex hormone, testosterone, under the control of gonadotrophins from the pituitary gland.
The principal male sex hormone, see androgen.
Spasm and twitching of the muscles, particularly of the face, hands and feet. Caused by a reduction in the blood calcium level, as a result of under-active parathyroid gland, rickets, or alkalosis (high alkalinity of body fluids and tissues) due to loss of acids, high bicarbonate levels of hyperventilation.
Relating to the chest area.
The 12 bones of the spine to which the ribs are attached. They lie between the cervical (neck) and lumbar (lower back) vertebrae and are characterised by the presence of facets for articulation with the ribs.
The chest portion of the axial skeleton, including 12 thoracic vertebrae, 12 pairs of ribs, 12 costal cartilages and the sternum.
- Thrombocyte (platelet) Blood cell necessary for clot formation.
A blood clot.
A hormone secreted by the thymus gland and is involved in the development of T-lymphocytes for cell-mediated immunity.
A bi-lobed organ in the root of the neck. It is involved with the development of lymphoid tissue and immune response. T-lymphocytes mature in the thymus.
A large endocrine gland situated in the base of the neck. It consists of 2 lobes, on either side of the trachea, which are joined by an isthmus. It is concerned with the regulation of the metabolic rate by the secretion of thyroid hormone (thyroxine and triiodothyronine). It is controlled by the release of thyroid-stimulating hormone from the pituitary gland.
An iodine-containing substance synthesised and secreted by the thyroid gland, that is essential for normal metabolic processes and mental and physical development. There are two thyroid hormones, triiodothyronine and thyroxine. Lack of these hormones gives rise to cretinism in infants and myxoedema in adults. Excessive production of thyroid hormones gives rise to thyrotoxicosis.
A hormone synthesised and secreted by the anterior pituitary gland under the control of thyrotrophin-releasing hormone, that stimulates activity of the thyroid gland. Defect is TSH production lead to over- or under- secretion of thyroid hormones.
See thyroid hormone.
The long inner and larger bone of the lower leg. Also known as the shin bone.
A collection of cells specialised to perform a particular function. The 33 cells may be of the same type (e.g. in nervous tissue) or of different types (e.g. in connective tissue). Aggregations of tissues constitute organs.
A muscular organ attached to the floor of the mouth. It helps in manipulating food during mastication (chewing) and swallowing; it is the main organ of taste; and it plays an important role in the production of articulate speech.
A mass of lymphoid tissue on either side of the back of the mouth. It is concerned with protection against infection. The term usually refers to either of the palatine tonsils, but below the tongue is another pair, the lingual tonsils. See also adenoids (pharyngeal tonsils).
The windpipe: the part of the air passage between the larynx and the main bronchi.
A carpal bone of the wrist.
A carpal bone of the wrist.
See thyroid hormone.
A carpal bone of the wrist.
A small, roughly rounded process of a bone.
Any abnormal swelling in or on a part of the body. The term is usually applied to an abnormal growth of tissue, which may be benign or malignant.
The part of the middle ear that consists of an air-filled space within the petrous part of the temporal bone. It is lined with mucous membrane and is connected to the pharynx by the Eustachian tube and to the outer ear by the eardrum (tympanic membrane).
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The inner and longer bone of the forearm. This is classed as a long-bone.
Either of a pair of tubes, 25 – 30 cm long, that conduct urine from the pelvis of kidneys to the bladder.
The tube that conducts urine from the bladder to the exterior. The female urethra is quite short (about 3.5 cm) and the male urethra is longer (about 20 cm). The male urethra as well as transporting urine, it receives the secretions of the male accessory sex glands (prostate and Cowper’s glands and seminal vesicles) and spermatozoa from the vas deferens; thus it also serves as the ejaculatory duct.
The part of the female reproductive tract that is specialised to allow the embryo to become implanted in its inner wall and to nourish the growing foetus from the maternal blood. The non-pregnant uterus is a pear- shaped organ, about 7.5cm long, and is suspended in the pelvic cavity. Its upper part is connected to the two Fallopian tubes and the lower part joins the vagina at the cervix.
The entire system of ducts and channels that conduct urine from the kidneys to the exterior. It includes the ureters, the bladder, and the urethra.
The periodic discharge of urine from the bladder through the urethra. It is initiated by voluntary relaxation of the sphincter muscle below the bladder and maintained by reflex contraction of the muscles of the 34 34 bladder wall.
The fluid excreted by the kidneys, which contains many of the body’s waste products. It is the major route by which the end-products of nitrogen metabolism (urea, uric acid and creatinine) are excreted. The other major constituent is sodium chloride, then over 100 other substances, often only present in trace amounts.
A space within the cytoplasm of a cell, formed by infolding of the cell membrane, which contains material taken in by the cell. White blood cells form vacuoles when they surround and digest bacteria and other foreign material.
The lower part of the female reproductive tract: a muscular tube, lined with mucous membrane, connecting the cervix of the uterus to the exterior. The wall of the vagina is sufficiently elastic to allow the passage of the newborn child.
The 10th cranial nerve, which originates in the medulla (motor component) and ends in the Pons varolii and Medulla oblongata (sensory component). It transmits information from the larynx, trachea, oesophagus, stomach, intestines, gall bladder, large arteries and veins. It transmits impulses to the pharynx, larynx, trachea, oesophagus, stomach, small intestine, ascending colon, pancreas, liver, spleen, kidneys, heart and visceral vessels.
Either of a pair of ducts that conduct spermatozoa from the epididymis to the urethra on ejaculation. It has a thick muscular wall the contraction of which assists in ejaculation.
See anti-diuretic hormone.
A blood vessel carrying blood from the tissues towards the heart.
Either of the two main veins, conveying blood from the other veins to the right atrium of the heart. The inferior vena cava, formed by the union of the right and left common iliac veins, receives blood from parts of the body below the diaphragm. The superior vena cava, originating at the junction of the two innominate veins, drains blood from the head, neck, thorax and arms.
Four small hollow spaces in the brain that are filled with cerebrospinal fluid. They contain the choroid plexus, which produces cerebrospinal fluid (CSF).
The 26 individual bones in the spinal column. The spinal cord passes through the vertebrae.
- Vestibule (of the ear) A cavity of the bony labyrinth that contains the saccule and utricle – the organs of equilibrium.
A minute particle that is capable of replication but only within living cells. Viruses are too small to be visible with a light microscope and too small to be trapped by filters. They consists of a core of nucleic acid (DNA or RNA) surrounded by a protein shell. Viruses cause many diseases, ranging from the relatively minor, e.g. common cold, to major life-threatening diseases, e.g. AIDS. Antibiotics are ineffective against viral diseases. Vaccination may help to protect against developing certain viral diseases.
Relating to the organ(s) of the body.
A thin plate of bone that forms part of the nasal septum.
The female external genitalia. Two pairs of fleshy folds – the labia majora and labia minora – surround the openings of the vagina and urethra and extend forward to the clitoris.
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Heavily myelinated central nervous tissue that is light in colour (in contrast to grey matter). It consists mostly of axons covered with the insulating lipid-protein sheath myelin.
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Either of a pair of bones that form the prominent part of the cheeks and contribute to the orbits.
The fertlisied ovum before cleavage begins. It contains both male and female pronuclei.
- Gray's Anatomy Contents
- Gray's Anatomy Subject Index
- About Classic Gray's Anatomy
- Note to Contributors of Gray's Anatomy
- Glossary of anatomy terms