2 week 11 Flashcards
blood pressure/MAP = ___ x ___
cardiac output x peripheral resistance
what happens to MAP when you increase CO?
MAP increases when TPR remains constant
what happens to MAP when CO remains constant?
MAP increases if TPR increases
whats Ohm’s law?
small decrease in BP = big decrease in CO = increase in peripheral resistance (HEART FAILURE)
diff bw venous pressure and central venous pressure?
VP: average VP within venous compartment
CVP: pressure in thoracic vena cava (near right atrium)
how does the skeletal muscle pump increase CVP?
- alternate contraction and relaxing, muscles act as pumps that help drive blood toward the central veins
- ex, when contract, distal valves close and proximal valves open, so blood flows to heart. when relax, distal valves open and proximal valves close, so blood moves away from heart.
how does the respiratory pump increase CVP?
- inhale: diaphragm down, rib cage expands. blood moves from abdomen (high pressure) to chest (low pressure) and fills heart.
- exhale: pressure gradient reverses, but reverse flow is prevented by valves in abdominal veins. since chest = higher pressure than right atrium, blood enters heart.
how does blood volume contribute to MAP?
- blood volume determined by fluid intake/fluid loss.
- fluid loss can be passive or regulated at kidneys.
- +fluid intake = +blood volume = +blood pressure
describe fast vs slow response to HIGH blood volume/pressure.
fast: cardiovascular system vasodilates to decrease CO.
slow: kidneys produce more urine to decrease blood volume.
describe short vs long term response to LOW blood volume/pressure.
short: baroreflex increases sympa activity to increase CO and TPR.
long: vasoconstriction of kidney vessel stops urine production to increase blood volume/pressure.
what is orthostatic hypotension? what is it caused by?
- drop in BP upon standing → dizziness
- caused by venous pooling (which lowers CVP and MAP)
what do veins do to increase CVP?
- reserve volume by being highly compliant (vasoconstricting!)
how does fluid flow across the capillary wall?
- from arteriole to venule.
- hydrostatic pressure = forces fluid OUT (filtration, BP) and decreases as move from arteriole to venule.
- oncotic pressure = forces fluid back IN (absorption, dilute protein) and remain constant.
- see slide 20
what happens to the ~3L of fluid leaks out of the capillaries each day, moves into the extracellular space?
taken up by lymphatic system (eventually return to right atrium)
how do barorecpetors measure increases in pressure?
- action potentials
- increased pressure = increased AP frequency
T or F: baroreceptors connect to the CNS?
true! medulla > cerebral cortex > outflow via parasympa system > SA node to moderate heart rate
if BP is low, ___ activity increases.
if BP is high, ___ activity increases.
sympa
parasympa
what does increased metabolic rate do for vascular resistance?
- oxygen gets consumed faster (concentration decreases in extracellular fluid)
- arterioles vasodilate to increase blood flow and oxygen delivery
- INTRINSIC
what does decreased blood flow do for vascular resistance?
- CO2 removal rates drop (concentration increases in extracellular fluid)
- arterioles vasodilate to increase blood flow and CO2 removal
- INTRINSIC
what does exercise do to blood flow, CO, heart rate, SV, MAP, and TPR?
- +blood flow, +CO, +heart rate, +SV
- small +MAP because -TPR due to vasodilation
what is ischemic heart disease?
build up of plaque leading to low blood flow and imbalance between the supply of oxygen and the myocardial demand
diff bw ischemic and hemorrhagic strokes?
- ischemic = build up of plaque or clot
- hemorrhagic stroke = burst of blood vessels, blood accumulates in brain leading to constriction
what do cholesterol lowering drugs do to cholesterol?
allow it to be excreted via feces
T or F: high LDL cholesterol = low # of events
false – high = high events (and vice versa)
