abduction - Answers The movement away from the median plane i.e. a lateral movement,
opposite of adduction. This movement is in the coronal plane
abscess - Answers "gone away' - presumably referring to the fate of the contents of an abscess.
A cavity containing pus and surrounded by inflamed tissue, generally due to a local infection.
acetabulum - Answers The large cup-shaped articular cavity, on each side of the pelvic girdle,
into which the ball shaped head of the femur fits to form the hip joint. Latin: acetum = vinegar,
used in the word 'acetabulum' meaning vinegar cup. The connection between acetum and acetic
acid is easy to see
acetlycholine - Answers A chemical substance (neurotransmitter) released by some nerve
endings, usually parasympathetic nerve endings
achilles tendon/calcaneal tendon - Answers The tendon attaching the triceps surae (calf
muscles) to the calcaneus at the heel
acquired resistance - Answers Resistance to microbial attack which develops as a response to
exposure to the causative agent. If the same microbe enters the system at a later date, acquired
immunity allows the body to mount a more rapid and generally more effective response.
Contrast with 'innate
action potential - Answers A self-propagating electrical impulse that occurs in excitable tissues
that is characterised by a transient reversal in the membrane potential.
acute - Answers Pertaining to a disease or illness with abrupt or sudden onset, intense
symptoms, and short duration
adaptation - Answers If a constant stimulus is applied to a sensor, the generation of sensory
nerve impulses decreases. Sensors are effective at detecting changing rather than constant
stimuli
adduction - Answers Movement towards the mid-line of the body. The reverse of abduction
ADH - Answers antidiuretic hormone. A hormone formed in the hypothalamus, released by the
pituitary gland in response to an increase in cerebrospinal fluid osmolarity. Promotes water
retention by increasing the permeability of kidney distal tubule and collecting duct cells to water.
Also known as vasopressin
adipose - Answers A connective tissue consisting mainly of fat cells
ADP - Answers Adenosine diphosphate
adrenaline - Answers main hormone produced by the adrenal medulla. Also called epinephrine
, adrenoceptor - Answers Receptors which interact with catecholamines. Can be classified as
alpha or beta
aerobic organisms - Answers Organisms which use oxygen as the terminal electron acceptor in
the oxidation of energy-providing nutrients
afferent lymphatic vessel - Answers A vessel carrying lymph which is entering a lymph node.
Contrast with 'efferent'
affinity - Answers The strength of binding of one molecule to another at a single site, such as
may occur between an antibody and the corresponding antigen
agglutinate - Answers The visible aggregation (clumping) of antigen, or the action of forming
such an aggregate
agglutination - Answers An antigenantibody reaction in which an antigen forms a lattice with
soluble antibody
agonist - Answers A muscle when it is contracting concentrically to move a joint
aldosterone - Answers A steroid hormone secreted by the adrenal cortex that acts on the
kidneys to promote sodium retention and potassium excretion
allergen - Answers An antigen which has the capacity to cause an allergy
amino acids - Answers A group of molecules containing at least one carboxyl (acid) group and
at least one amino group, which form the chief constituent of protein.
anaerobic - Answers Not utilising oxygen. Anaerobic metabolism uses an electron acceptor
other than oxygen e.g. in mammalian muscle with an inadequate oxygen supply and in red blood
cells, pyruvate accepts these electrons and is converted to lactate
analog systems - Answers a continuous electrical signal representing a specific condition, such
as temperature, electrocardigram waveforms, telephones, or computer modems.
anaphylatoxin - Answers Any substance capable of triggering the release of substances from
mast cells. For example, an anaphylotoxin may cause the release of histamine from mast cells
in such quantity that the result is lifethreatening. More usually, a small amount of substance is
released, and contributes to a local inflammatory reaction.
anatomical position - Answers Standing upright, looking straight ahead with the palms of the
hands facing forward and the feet together. The position of reference for all anatomical
descriptions.
angiotensin II - Answers A vasocontrictor substance activated by renin; it triggers the release of
aldosterone