17. Circulation & Hemodynamics Pt II Flashcards
what is the direction of microcirculation
small arterioles –> meta-arterioles –> thru precap shincter –> caps –> venules
how does exchange of O2 & CO2 occur
diffuse thru endothelial walls bc lipid soluble
what is the reason we have clefts in the caps
to allow water souble substances thru
h2o, glucose, electrolytes, etc
what drives movement of fluid in caps
hydrostatic P & osmotic P
what is starlings equation
forces moving fluid out - forces moving fluid in
where does filatration occur most
arteriole end
where does filtration occur least
venous end
how can Pc be elevated
heart failure
increase Pv
what happens with decreased albumin
decrease (pi)c
how can Pi be affected
restricted lymphatic flow
increased driving force out of cap
how can (pi)i be affected
restricted lymph flow
inflam
what is myogenic control
if BP increased –> arterial walls stretched –> vasoconstrict walls to maintain constant flow
what is active hyperemia
increase metabolic activity –> increase blood flow
what is reactive hyperemia
increase blood flow after period of occlusion
what is the basis of shear
vascular bed dilated bc increased metabolic demand–> flow of upstream arterioles increase –> increase shear (friction) –> release NO –> vasodilation to augment downstream metabolif effect
what is the result of histamine & bradykinin
arteriolar vasodilation
increase capillary porosity (Kf)
edema in response to damaged tissue
what is the response to serotonin
vasoconstrict due to tissue damage
what kind of regulation controls coronary circulation
metabolic control
what kind of control does cerebral circulation have
metabolic control
where is pulmonary vascular pressure the highest
RV & pul A
Rv- 24 to 0/4 mm Hg
pul A - 24 to 10/16 mm Hg
what is the resistance of pulmonary vasculature compared to systemic
very low
what happens in the pulmonary circulation whern there is hypoxia
vasoconstriction
pulmonary arterial system is more _________ than systemic arteries
compliant
-so small changes in mean pressure will dilate As alot –> reduce resistance to maintain low pressure during large changes in flow
how is vasculature regulated in skeletal Ms
at rest- central, baroreceptor control (sym innervation - NE to alpha 1 & E to beta-1)
active - local control
what is the role of sym innervation to skin
body temp regulation
what is a Right to Left shunt
blood passing from systemic Vs to systemic As w/o passing thru fxnal lung tissue
what is Left to Right shunt
blood passing from systemic As to systemic Vs & bypassing caps
