Regulation of Blood Flow

Question 1

What are some factors that may change PP?

Answer 1

SV, compliance, TPR

Question 2

Besides Q = △P/R what is another formula for flow?

Answer 2

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)

Question 3

What is the formula for measuring O2 consumption?

Answer 3

VO2= CO x (CaO2 - CvO2)

Question 4

What are the 2 mechanisms used in autoregulation of BF?

Answer 4

metabolic mechanism and myogenic regulation

Question 5

What are some metabolic autoregulatory metabolites used for regulation of BF?

Answer 5

adenosine, CO2, H+, and K +

Question 6

What is the myogenic mechanism by which BF is regulated?

Answer 6

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

Question 7

What are some autoregulating tissues of the body?

Answer 7

cerebral circulation
coronary circulation
skeletal muscle vasculature during exercise

Question 8

Blood flow is independent of or dependent on nervous reflexes (e.g carotid sinus) or circulating humoral factor? (in autoregulating tissues)

Answer 8

Q is independent of nervous reflexes and circulating humoral factor and in most cases is related to tissue metabolism

Question 9

What is intrinsic regulation (autoregulation)?

Answer 9

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)

Question 10

What is extrinsic regulation of BF?

Answer 10

these tissues are controlled by nervous and humoral factors originating outside the organ

Question 11

Difference between flow control in resting vs exercising muscle.

Answer 11

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

Question 12

Describe blood flow in left coronary vasculature during systole?

Answer 12

very little

Question 13

What part of the cardiac cycle (systole or diastole) is the most BF through right coronary vasculature?

Answer 13

greatest under normal conditions is diastole

Question 14

Describe venous PO2 in coronary circulation.

Answer 14

Extremely low because they extract almost all the O2

Question 15

Coronary BF formula?

Answer 15

coronary BF = stroke work x HR

Question 16

What is cerebral circulation mostly mediated by? Is baroreceptor reflex regulation seen here?

Answer 16

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

Question 17

What is cutaneous circulation regulated by?

Answer 17

almost entirely by sympatehtic adrenergic nerves which cause vasoconstriction

Question 18

How does increased skin temperature effect BF regulation?

Answer 18

increased skin T causes vasodilation

Question 19

Where are the temperature sensitive neurons in the body found? (set point)

Answer 19

anterior hyopthalamus

Question 20

What are the 3 major arteries that supply the splanchnic organs?

Answer 20

celiac, superior, and inferior mesenteric arteries

Question 21

When fever develops what are some mechanisms the body uses to reach new higher set point?

Answer 21

heat conserving and heat generating mechanisms like shivering and cutanous vasoconstriction

Question 22

How does low alveolar PO2 affect pulmonary vasculature?

Answer 22

causes hypoxic vasoconstriction

Question 23

Describe the mechanism by which pulmonary pressure remain low even during exercise where CO (cardiac ouput) is high?

Answer 23

there is recruitment of previous unperfused capillaries and distension (highly compliant vessels)

Question 24

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.

Answer 24

Question 25

Describe MAP of the body under excercise?

Answer 25

slight increase

Question 26

Describe vascular resistance under cardiovascular stress (exercise)

Answer 26

large decrease

Question 27

How does regular exercise affect the muscle ability to utilize O2?

Answer 27

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