Term
| what is the best way to change the flow to a region? |
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Definition
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Term
| where does the greatest resistance in the vasculature reside? |
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Definition
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Term
| true or false, all exchange of gases and nutrients takes place at the capillaries? |
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Definition
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Term
| why are veins called capacitance vessels? |
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Definition
| because of their ability to act as a blood reservoir |
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Term
| what are three functions of vascular cells? |
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Definition
| contractility (control resistance), plasticity (hypertrophy), secretion |
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Term
| define vascular tone and vasomotion. |
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Definition
vascular tone - state of contraction due to intrinsic and extrinsic factors
vasomotion - a change in the caliber of a blood vessel |
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Term
| what affect does calcium have on vascular smooth muscle cells and what factors raise/lower intracellular calcium? |
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Definition
calcium causes the cells to contract
norepinephrine, angiotensin, acetylcholine and other things that lower cAMP raise intracellular Ca
prostacylin, beta adrenergics and others that raise cAMP or cGMP lower intracellular Ca |
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Term
| define rarefaction and what role does it have in vascular resistance. |
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Definition
the reduced density of vessels as a result of vessel closure,
this would raise the resistance through a region |
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Term
| what role do precapillary sphincters play in microcirculation? |
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Definition
| they can close when they are stimulated by local factors and shut off flow to a certain region, this is necessary because capillaries do not have smooth muscle surrounding them |
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Term
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Definition
it is a vessel that is part arteriole part capillary
it has discontinuous smooth muscle around it. |
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Term
| explain how small and large molecules are transported across the capillaries. |
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Definition
| small molecules are filtered or diffuse across the capillary, whereas large molecules cross via pinocytosis and vesicular transport |
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Term
| where are capillaries with tight junctions, fenestrations, and sinusoids found? |
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Definition
the brain
the kidneys, intestines, and endocrine glands
the liver, spleen and bone marrow |
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Term
| what are some endothelial derived vasodilators / vasoconstrictors? |
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Definition
dilator - nitric oxide, prostacyclin
constrictor - endothelin, angiotensin II |
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Term
| what are some metabolic processes of vascular endothelium? |
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Definition
| process vasoactive factors, breakdown bradykinin |
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Term
| why is nitric oxide not able to control overall blood pressure and what causes its release? |
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Definition
because it is very short lived and only acts on local tissue
sheer stress and/or endothelial cell receptor activation |
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Term
| what amino acid is important in NO production? |
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Definition
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Term
| what is the difference between endothelium depending / independent reactions and what are some activators of each? |
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Definition
dependent require endothelium for reaction, whereas independent do not, the factor acts directly on the smooth muscle
independent vasoconstrictor is vasopressin
independent vasodilator is ANP
dependent vasoconstrictor is endothelin
dependent vasodilator is NO, PGI2 |
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Term
| what is endothelium hyperpolarizing factor and what role does it play on the vasculature? |
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Definition
| it is a factor secreted by endothelial cells that tell the smooth muscle cells to hyperpolarize and thus dilate |
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Term
| describe vascular wall role in platelet activity during a healthy and injured state. |
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Definition
healthy endothelium releases vasodilators and EDRF's which prevent platelets from sticking to them
when the endothelium is injured the lack of these factors causes vasoconstriction and platelet aggregation |
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