Regulation of Blood Flow Flashcards
What are some factors that may change PP?
SV, compliance, TPR
Besides Q = △P/R what is another formula for flow?
Q (flow) = O2 consumption / [O2]pv - [O2]pa
(or can substitue pulmonary venous blood for arterial O2 content and pulmonary artery values for venous O2)
What is the formula for measuring O2 consumption?
VO2= CO x (CaO2 - CvO2)
What are the 2 mechanisms used in autoregulation of BF?
metabolic mechanism and myogenic regulation
What are some metabolic autoregulatory metabolites used for regulation of BF?
adenosine, CO2, H+, and K +
What is the myogenic mechanism by which BF is regulated?
perfusing pressure causes stretch in arteriolar wall; because of inherent ability to vasoconstrict when stretched this stretch will cause the arteriole radius to decrease and BF won’t increase significantly
What are some autoregulating tissues of the body?
cerebral circulation
coronary circulation
skeletal muscle vasculature during exercise
Blood flow is independent of or dependent on nervous reflexes (e.g carotid sinus) or circulating humoral factor? (in autoregulating tissues)
Q is independent of nervous reflexes and circulating humoral factor and in most cases is related to tissue metabolism
What is intrinsic regulation (autoregulation)?
when the control mechanisms regulating arteriolar smooth muscle are entirely within the organ itself
BF regulated; not resistance (So resistance is changed in order to regulate flow)
What is extrinsic regulation of BF?
these tissues are controlled by nervous and humoral factors originating outside the organ
Difference between flow control in resting vs exercising muscle.
Resting muscle is increased or decreased via sympathetic alpha-adrenergic activity
exercising muscle has intrinsic auto-regulation and release vasodilator metabolites and the muscle pump also regulates
Describe blood flow in left coronary vasculature during systole?
very little
What part of the cardiac cycle (systole or diastole) is the most BF through right coronary vasculature?
greatest under normal conditions is diastole
Describe venous PO2 in coronary circulation.
Extremely low because they extract almost all the O2
Coronary BF formula?
coronary BF = stroke work x HR
What is cerebral circulation mostly mediated by? Is baroreceptor reflex regulation seen here?
PCO2
hypoventilation increases PCO2> increases cerebral BF
hyperventilation decreases PCO2 > decreases cerebral BF
PO2 only affects if signicantly reduced which would increase cerebral blood flow
Baroreceptor reflex not seen
What is cutaneous circulation regulated by?
almost entirely by sympatehtic adrenergic nerves which cause vasoconstriction
How does increased skin temperature effect BF regulation?
increased skin T causes vasodilation
Where are the temperature sensitive neurons in the body found? (set point)
anterior hyopthalamus
What are the 3 major arteries that supply the splanchnic organs?
celiac, superior, and inferior mesenteric arteries
When fever develops what are some mechanisms the body uses to reach new higher set point?
heat conserving and heat generating mechanisms like shivering and cutanous vasoconstriction
How does low alveolar PO2 affect pulmonary vasculature?
causes hypoxic vasoconstriction
Describe the mechanism by which pulmonary pressure remain low even during exercise where CO (cardiac ouput) is high?
there is recruitment of previous unperfused capillaries and distension (highly compliant vessels)
Describe if there is an increase or decrease in BF(CO), pulmonary arterial pressure, pulmonary vascular resistance, pulmonary BV, number of perfused capillaries, and capillary surface area, in the pulmonary circuit during exercise.
Describe MAP of the body under excercise?
slight increase
Describe vascular resistance under cardiovascular stress (exercise)
large decrease
How does regular exercise affect the muscle ability to utilize O2?
an increased number of arterioles, which decreases resitance
an increased capillary density which increases surface area and decreases diffusion distance
an increased number of oxidative enzymes in mitochondria
