Download Physiology Objectives 17

Physiology Objectives 17
1.
Three ways that organ blood flow is controlled:
a.
Autonomic control
b.
Myogenic and metabolic control
c.
Humoral control
2.
Myogenic theory: the cause of autoregulation; as flow decreases, a reflex
response causes vasoconstriction to keep flow constant and vice versa when flow
increases
Metabolic theory: metabolites (ADP, H+, K+, lactate, CO2) cause vasodilation,
when they are washed out from the increased flow, the blood vessel contracts
back to normal size
3.
Local influences on organ blood flow: metabolic factors, NO, ADH,
angiotensin II, histamine, bradykinin, serotonin, and prostaglandins can all have
effects on blood flow with vasoactive effects
Nitric oxide: produced by nitric oxide synthase, NO diffuses into smooth muscle
cells and activates a cGMP pathway and vasodilation (similar to ACh) NOS is
activated by several agonists, most notably shear stress which causes intracellular
Ca2+ levels to increase and vasodilation (flow induced vasodilation)