Local control of blood flow Flashcards
Extrinsic vs intrinsic regulation of blood flow (how are they controlled)
E- Nervous system & humoral
I- Blood vessels in the immediate vicinity, local hormones,
What is the main factor in acute control of blood flow?
Tissue metabolic activity
When PaO2 drops by 25%, how much is blood flow to that area increased?
3 fold
When do precapillary sphincters open?
When the tissue requirements rise
Examples of active hyperemia vs reactive hyperemia
Active- exercise
Reactive- after torniquet is released
Active hyperemia can increase blood flow ___ x fold, but cereberal blood flow only increases ____ fold
50x
2x
Autoregulation definition
The ability of an organ to maintain constant blood flow despite changes in perfusion pressure
Myogenic and metabolic mechanisms
CPP formula and range
MAP-ICP or CVP whichever is higher
5-12
Nitric oxide pathway main contributor and effect
cGMP
Vasodilation
PDE inhibitors main sites
Penis- increase erection time
Lungs- decrease PVR
NO effect on platelets
Inhibits
What part of the lung does NO go to and what does it do?
Ventilated areas only
Increases blood flow
Improves VQ
Prostacyclin effect on blood vessels and platelets
Vasodilation, inhibits platelets via cAMP
Endothelin on blood vessels
Vasoconstricts
How is endothelin stimulated?
Damage to endothelium
(damages NO and prostacyclin vasodilation)
