Outline the mechanisms that control regional skeletal muscle blood flow.
Candidates were expected to present the cellular mechanisms underlying the control of
skeletal muscle blood flow. Many candidates correctly identified a role for sympathetic
nervous system, metabolic (e.g. vasodilator metabolites such as CO2, H+, K+, lactate and
adenosine), vasoactive substances released by endothelium (nitric oxide, prostacyclin,
endothelin 1, etc.) and autoregulatory control but failed to present any details of direction
and magnitude of control. Better answers also mentioned humeral (e.g. catecholamines,
vasopressin, ANP, angiotensin II, histamine, serotonin, etc.) or myogenic control (i.e. when
the pressure within a smooth muscle blood vessel is suddenly increased, the vascular
smooth muscle is stretched.