Local Regulation Of Blood Flow Flashcards
How is blood flow regulated?
Neural and endocrine
Four physical determinants of blood flow
Pressure change, length of vessel, radius, viscosity
Most important element of blood flow
Radius (to power of four)
What is main resistance to blood flow?
Arterioles - smooth muscle
Primary innervation of smooth muscle
Parasympathetic
How does adrenaline increase blood pressure?
Action on a1 and b2
Equation for flow
(Pressure change x radius ^4) / (viscosity x vessel length) a
Humoral regulation of blood flow
Adrenaline B2 receptors on vascular smooth muscle, atrial natriuretic peptide (vasodilation) and angiotensin ii, vasopressin - A1 - vasoconstriction
Neurogenic regulation of blood flow
Release of adrenaline binding to a1
Adrenaline and blood flow
Adrenaline has higher affinity for B2 but there are more A1, high dose of adrenaline leads to overall vasoconstriction and an increase in arterial BP. Physiological levels of adrenaline cause vasodilation through binding to B2 receptors within skeletal muscle vascular beds, decreasing BP
What does b2 do to blood flow?
Vasodilation
Endothelial cells
Release nitric oxide in response to increased metabolic demand or increased stress on endothelium
Release endothelin - a vasoconstrictor, stimulated by angiotensin ii and vasopressin, inhibited by NO
Release vascular endothelial growth factor to promote angiogenesis
Chemical and physical change in endothelial cells when exercise
Decreased pO2 Increased pCO2 Increased K+ Increased lactate Decreased pH Increased temperature
What does NO do?
Released to vasodilator
How to return blood flow to normal?
Increased BP
Increased stretch of arteriolar smooth muscle
Increased calcium influx
Smooth muscle contraction and vasoconstriction
Blood flow normal
