Lecture 18: Blood distribution and control of local circulation

Question 1

The max HR is approximated at what?

Answer 1

220-age

Question 2

Is the percentage of the CO going to various organs/regions equal?

Answer 2

No it is not and it can change from minute to minute depending on conditions

Question 3

What is CO at rest?

Answer 3

5 L/min

Question 4

What is CO while exercising?

Answer 4

25 L/min

Question 5

True or false? Blood flow to the tissue is matched to the needs of the tissue.

Answer 5

true

Question 6

Active tissue can require up to ______ increase in blood flow.

Answer 6

20x

Question 7

Even though active tissue can require up to 20x increase in blood flow, CO only increases 6x, so what must happen?

Answer 7

Changes in microcirculation must take place to increase blood flow to the active tissue even more

Question 8

If blood flow exceeds the need of the tissue, what happens?

Answer 8

regulatory mechanisms will decrease blood flow

Question 9

Does the SNS innervate blood vessels?

Answer 9

yes

Question 10

The PNS doesn’t innervate the majority of blood vessels but does regulate what?

Answer 10

dilation of some blood vessels in specific areas of the body (genitals)

Question 11

What is the primary controller of coronary and cerebral blood flow?

Answer 11

Local metabolism and release of vasodilator substances

Question 12

Epinephrine binds to B2 receptors and so these receptors are said to be stimulated. What do these stimulated receptors cause?

Answer 12

Vasodilation (lactate can also cause vasodilation)

Question 13

What are some factors that are released from metabolically active or hypoxic tissues that cause relaxation of smooth muscle and vasodilation of small arteries and arterioles?

Answer 13

adenosine, CO2, H+, K+

Question 14

Endothelial cells release nitric oxide in response to what?

Answer 14

sheer stress from blood flow

Question 15

The nitric oxide that’s released from the endothelial cells will diffuse into smooth muscle in local area and cause what?

Answer 15

smooth muscle relaxation (vasodilation)

Question 16

What does Endothelin cause?

Answer 16

vasoconstriction

Question 17

What 3 autocrine/paracrine peptides cause arteriole dilation and capillary permeability?

Answer 17

Bradykinin, prostaglandins, and histamine

Question 18

What is a form of long term regulation of blood flow?

Answer 18

angiogenesis

Question 19

Tissues release angiogenic factors (VEGF, FGF) in response to what?

Answer 19

chronic ischemia

Question 20

What happens to the oxygen demand in muscles during exercise?

Answer 20

increases & blood flow to those tissues increase as well

Question 21

What happens to the oxygen consumption (VO2) in skeletal muscle during exercise?

Answer 21

increases

Question 22

What happens to the arteriovenous oxygen difference (a-vO2 difference) in skeletal muscle during exercise?

Answer 22

increases

Question 23

What is the A-VO2 difference?

Answer 23

the difference in the PO2 between the arterial blood and the venous blood

Question 24

If the A-VO2 increases, what does it represent?

Answer 24

an increase in oxygen uptake by that tissue

Question 25

TPR is the primary determinant of what?

Answer 25

diastolic blood pressure

Question 26

What does RPP stand for?

Answer 26

rate pressure product

Question 27

What does RPP indicate?

Answer 27

the work of the heart

Question 28

What are the formulas for RPP?

Answer 28

HR x SBP

HR x mean arterial pressure