Table 1.

Key terms defined for the non-specialist

Apoptotic cell death – cell death programmed to occur over hours or days usually by chemical signals from its neighbours

Baroreceptor responses – response to input sensing pressure, usually in blood vessels such as the carotid sinus

Chemosensitivity – sensing of changes in respiratory gases (carbon dioxide and oxygen) in the brain stem and carotid bodies

Erythropoiesis – red blood cell production

Haemolysis – lysis of red blood cells with release of haemoglobin

Hypoxaemia – low blood oxygen

Hypoxia-Inducible Factor (HIF) – protein which is destroyed continuously when there is adequate oxygen but is stabilized during hypoxia and upregulates:

Erythropoietin – hormone which increases red cell production

Vascular endothelial growth factor (VEGF) – induces vessel growth (angiogenesis)

Endothelin – powerful constrictor of blood vessels

Nitric Oxide – powerful dilator of blood vessels

S-nitrosothiols (SNO) – molecules formed after the reaction of nitric oxide with a critical cysteine residue on proteins

Tidal volume – volume of air inhaled and exhaled at each breath