Q | A |
What are the two major autoregulation mechanism which controls the local blood flow! | Metabolic and myogenic control. |
What happens with increased BL through capillaries? | Increased venous return-> Increased CO |
Which two phases can the local blood flow control be divided in? | 1)Acute - rapid change constriction/dilatation of arteriols, metarteriol et spincters 2)Long-term control provides a better control by increasing/decreasing the physical size and number of blood vessels supplying the tissues. |
Which are the two basic theories for regulation of local blood control? | 1)vasodilator theory (less availability of metabolit->formation of vasodilation substances like adenosine, CO2, AMP, histamine, K, H etc.) 2) Oxygen lack theory |
What is hyperemia? | Increased blood flow to organ or tissue. |
What is reactive hyperemia? | If blood suppy to a tissue is blocked for seconds or hours and the is unblocked there will be a blood flow 4X-7X the normal and lasts long enough to repay exactly the tissue oxygen dificient that has accord during the period of occulusion. |
What is active hyperemia? | Increased local metabolism -> decreased nutrition and increased vasodilation substances -> increased blood flow |
Explain the metabolic theory! | When arterial pressure becomes too great and we have to much flow to the tissue -> vasoconstriction. |
Explain the myogenic theory! | High arterial pressure -> vessel stretch -> vasoconstriction-> Blood flow back to normal
(Can cause vicios circle) |
Increased flow (shear stress) leds to? | Inhibition of endotelin (production in endotels) -> relaxation of vessel |
Why is the endothelial derived relaxing factor, NO importent? | Because it causes upstream (large vessel) dilation. |
How does high pressure effect the vessels? | The vessels gets stretched -> less resistens. |