3 & 10: Vascular Function Flashcards
Which vessels have the highest proportion of smooth muscle?
Small arteries and arterioles
Fluid movement is dependent on the balance between ____ and ____ pressures
- Hydrostatic
- Colloid osmotic
Which organs receive the highest amount of blood flow
- At rest
- With exercise?
- At rest: liver, kidney
- With exercise: skin, muscle
What is autoregulation?
The intrinsic tendency of an organ to maintain constant blood flow despite changes in perfusion pressure
Vascular autoregulation demonstrates the link between ____ and ____
Blood flow and metabolism
What is reactive hyperaemia?
The transient increase in blood flow to an organ following a brief period of tissue ischemia
What is the mechanism of myogenic control?
- Increased transmural pressure causes wall distension
- Results in depolarisation of VSM cells (stretch sensitive ion channels)
- Results in contraction
How do endothelial cells regulate vessel tone?
Release of NO in response to shear force causes vasodilation
What is the downstream result of stimulation of alpha 1 receptors?
- Gq activates PLC
- Increases DAG and IP3
- Results in increased Ca2+
- Results in vasoconstriction
Circulating Ach binds to ___ receptors in vascular endothelium resulting in synthesis of __
M3
NO
Why do adrenaline and noradrenaline have different vascular effects?
Different affinities for Alpha and beta-2 receptors (B2 has high affinity for adrenaline)
B2 adrenergic receptors are present in pre-capillary vessels only in ___ and ___ circulations.
Skeletal muscle and splanchnic
What local regulatory system has the most effect on skeletal muscle circulation in exercise?
Vasodilator metabolites (metabolic)
What is the downstream result of stimulation of beta 2 receptors?
- Linked to Gs protein
- Stimulates adenylate cyclase
- Results in increased cAMP and vasodilation
What is the predominant regulator of cerebral circulation
Local control (pH, pCO2, pO2, K+)
