Circulation: Local Control of Blood Flow Flashcards
what are the 2 types of blood flow control?
local
long term
what are 3 aspects of local control?
- tissue needs
- neural
- hormonal
what factor has the greatest impact on local control?
tissue needs
what are 2 aspects of long term control?
- kidney
- angiogenesis
what is angiogenesis?
change in number or size of blood vessels
(occurs with tumors -> highly vascularized)
what 3 things can stimulate the growth of new blood vessels?
- vascular endothelial growth factor (VEGF)
- fibroblast growth factor
- angiogenin
each of these cause increased vasculature of tumors
what is the vasodilator local control theory?
increased tissue metabolism causes release of vasodilators:
- increases vessel size
- decreases resistance and
- increases blood flow
what is the oxygen/nutrient lack local control theory?
increased tissue metabolism or decreased O2 causes:
- precapillary sphincter to relax
- more blood flow to capillary
- increases vessel size
- decreases resistance
- increases blood flow
both theories of local control of blood flow lead to…
increased vessel size + decreased resistance = increased blood flow
blood flow is proportional to ____
blood pressure
name the metabolic vasodilators
- adenosine
- AMP, ADP
- CO2 (lack of O2)
- H+ (lower pH)
- K+
- lactic acid
name the other vasodilators
- NO
- bradykinin
- substance P
- histamine
- leukotrienes
- lack of O2 (CO2)
name the vasoconstrictors
- serotonin
- NE
- epinephrine
- angiotensin II
- vasopressin (ADH)
- endothelin
(contain “in”)
what is active hyperemia?
increase in blood flow & BP brings more nutrients & O2 into tissue
what is reactive hyperemia?
increase in blood flow & BP brings increase in O2 to tissues, which causes rebound vasoconstriction back to normal size
active hyperemia and reactive hyperemia account for the theory of ____
autoregulation
what is the autoregulation theory?
if a vessel has either increased blood flow OR increased BP (=increased size), the blood vessel will react by decreasing in size (vasoconstriction), and vice versa
what percent of blood volume is in the systemic circulation?
84%
what percent of blood volume is in the systemic veins?
64% (*veins have the most volume)
what percent of blood volume is in the cardio-pulmonary system?
16%
which vessels have the largest compliance?
veins
what 3 factors determine venous return?
- skeletal muscle pump
- respiratory pump
- sympathetic NS
backflow in veins is prevented by ____
valves
problems with valves leads to ____
varicose veins
central venous pressure is equal to…
right atrial pressure
(0-4mmHg)
mean arterial pressure is equal to…
2/3 diastolic + 1/3 systolic
pulse pressure is equal to…
systolic - diastolic
what factors increase pulse pressure?
increased systolic pressure:
- increased SV
- increased HR
- decreased aortic compliance
what changes would occur to vascular conductance, capillary filtration, and blood flow in response to decreased vessel diameter?
all would decrease
under normal physiological conditions, blood flow to the skeletal muscles is determined mainly by ____
metabolic needs
if nitric oxide is infused into the brachial artery, what changes would occur to capillary hydrostatic pressure, interstitial hydrostatic pressure, and lymph flow?
all would increase
during exercise, increased plasma adenosine concentration leads to…
arteriolar vasodilation
what change in arterial compliance would increase pulse pressure?
decrease
what would happen to venous hydrostatic pressure in the legs with movement of leg muscles?
decrease
