Vascular Hemodynamics Flashcards
formula for mean arterial pressure
- MAP= CO x SVR
if we increase resistance, what is the effect on flow
- decreases flow
what is the resistance of the systemic circulation
- high resistance system
what is the affect of larger resistances on pressure drops for the same flow
- lead to larger pressure drops
relationship between length and resistance
- proportional
relationship between viscosity and resistance
- proportional
relationship between radius and resistance
- inverse
resistors in series
- summate
resistors in parallel
- 1/RT to summate
each individual resistance in parallel compared to total resistance
- greater than total resistance
which part of the vascular system has the highest total resistance
therefore
- arterioles
- largest pressure drop occurs there
why do arterioles have the largest pressure drop
- they have the smallest diameter
what has the next highest resistance
- capillaries
compliance is the measure of _____ of a vessel wall
- distensibility
compliance is the measure of the _______ of the vessel
- capacitance
decreased compliance means
- increased stiffness
which is more compliant (veins or arteries)
- veins
compliance formula
- compliance = volume / pressure
affect of atherosclerosis and age on compliance
- decreased compliance
blood flow is determined by _____ of the vessels
- resistance
auto regulation maintains blood flow by altering _____
- resistance
myogenic mechanism with decreased blood flow
- decreased blood flow
- less stretch on vascular smooth muscle
- Ca2+ channels close
- vasodilation
- increase in blood flow
myogenic mechanism for increase in blood flow
- increase in blood flow
- increased hydrostatic pressure
- more stretch on vascular smooth muscle
- Ca2+ channels open
- vasoconstriction
- decreased blood flow
levels of these for vasodilation:
K H O2 CO2 adenosine
- K increase
- H+ increase
- O2 decrease
- CO2 increase
- adenosine increase
role of histamine
- increases NO
- increases capillary permeability
endothelin causes
released by
- vasoconstriction
- endothelial cells
thromboxane causes
released by
- vasoconstriction
- platelets
serotonin causes
released by
- vasoconstriction
- platelets
vasoconstriction mechanisms
- activated of GPCR that increase IP3
- close K+
- activate Ca2+
vasoconstriction acts through which receptors
- Gq coupled receptors
things that activate vasoconstriction
- NE (via alpha-AR)
- angiotensin
- vasopressin
- endothelin
vasodilation mechanism
- activates PKA or PKG
- activates K+ channels or Ca2+ pumps
vasodilation acts through which receptors
- Gs receptors
things that activate vasodilation
- adenosine
- prostaglandins
- prostacyclins
- epinephrine (via Beta-AR)
- nitric oxide
- histamine
what is the tendency of a hollow organ to recoil toward its original dimensions upon removal of a distending force?
what is its relationship to compliance
- elastance
- reciprocal of compliance
passive component of vascular compliance
- extracellular matrix proteins
active component of vascular compliance
- smooth muscle tone
compliance measured on a graph
- slope of the curves
venous compliance is decreased by
- alpha 1 adrenergic receptors on venous smooth muscle are activated by catecholamines
effect on venous compliance on venous return to the heart
- increases venous return to the heart
what provides the most potent regulation of coronary vascular resistance
- metabolic control
LaPlace Equation
T = (P x R)/h
T=tension
P = pressure
R = radius
h = wall thickness
relationship of tension of the vascular wall to the risk of rupture
- as tension increases, risk of rupture increases
diagnostic tests to do for aortic aneurysm
- chest CT scan
- echo
capillary reserve in myocardial diastole
- there is not capillary reserve
physical exam of aortic dissection
- blood pressures uneven in the 2 arms
