Local and extrinsic controls of peripheral circulation Flashcards
Control of peripharl vascular resistance includes?
Instrinsic controls: local paracrine signaling or metabolic products
Extrinsic controls: nerual and hormonal
Main method of delivering more oxygen to myocardial tissue during exercise?
Increasing coronary blood flow by incrinsic, local autoregulatory control
Heart already extracts a large amount of oxygen from blood
Effect of CO2 on cerebral circulation
Potent vasodilator
Main control (intrinsic autoregulatory)
What mechanism controls blood flow in cutaneous circulation?
Neural mechanisms (sympathetic division of ANS)
Mediator is norepi
Under what pressure(s) does blood flow change linearly with BP?
Under 50 mmHg and over 150 mmHg
Reactive hyperemia
Occurs after tissue blood supply is blocked for a short time - after unblocking - blood flow increases immediately 4-7 times normal
active hyperemia
Occurs when tissue metabolic rate increases, that immediately increases the rate of blood flow through tissue (i.e. exercise, GI gland during a hypersecretory period, or the brain during increased mental activity)
What are the substrates for endothelial-derives NO synthase?
L-Arg and O2 and reduction of inorganic nitrate
Myogenic autoregulation
Hormonal vasoconstrictors
- Angiotensin II
- Vasopressin (ADH)
- Serotonin
What causes dilation of arterioles and constriction of venules?
Bradykinin and histamine
What is the normal coronary blood flow in a healthy adult?
5% of CO or ~250 ml/min,.