Lecture 18

Question 1

the percentage of cardiac output going to various organs/regions is not equal and can ______ minute to minute depending on conditions.

Answer 1

change

Question 2

the percentages of blood flow distribution are the percentage of _____ which is flowing to each organ

Answer 2

CO (carbon monoxide)

Question 3

at rest, the CO is ___ L/min

Answer 3

5

Question 4

when exercising, CO is ____ L/min

Answer 4

25

Question 5

active tissue can require up to _____times increase in blood flow

Answer 5

20

Question 6

cardiac output only increases ~___times, therefore changes in microcirculation must take place to increase blood flow to the active tissue even more

Answer 6

6

Question 7

if blood flow exceed the need of the tissue, regulatory mechanisms will _______ blood flow

Answer 7

decrease

Question 8

______ muscle in small arteries and arterioles can be stimulated to contract or relax via nervous signals, hormonal stimuli, stretch, and changes in chemical environment (doesn’t require an action potential to stimulate contraction like skeletal muscle does)

Answer 8

smooth

Question 9

SNS or PNS? innervated blood vessels

Answer 9

SNS

Question 10

SNS or PNS? does not innervate the majority of blood vessels but does regulate dilation of some blood vessels in specific areas of the body, such as genitals

Answer 10

PNS

Question 11

generalized vasoconstriciton and venoconstriction due to stimulation of the _______ receptors

Answer 11

Alpha-1 adrenergic

Question 12

the coronary and cerebral circulations have poor ____ vasoconstrictor innervation so are spares the vasoconstrictor effect

Answer 12

SNS

Question 13

what are the primary controllers of coronary and cerebral blood flow since it isn’t the SNS?

Answer 13

local metabolism and release of vasodilator substaces

Question 14

in few vascular beds, activation of the SNS can cause vasodilation via activation of ____ receptors

Answer 14

Beta-2

Question 15

Activation of SNS (in vascular beds) leads to stimuation to __________ release from the adrenal glands

Answer 15

epinephrine

Question 16

the epinephrine in turn binds to ______ receptors in few vascular beds causing vasodilation

Answer 16

Beta-2

Question 17

what regulates the blood flow of various tissues?

Answer 17

SNS, local chemical factors, and angiogenesis

Question 18

factors that are released from metabolically active or hypoxic tissues include:

Answer 18

adenosine, CO2, H+, K+, and lactate

Question 19

factors that are released from metabolically active or hypoxic tissues cause _______ of smooth muscle and _________ of small arteries and arterioles

Answer 19

relaxation; vasodilation

Question 20

endothelial cells release _______ in response to sheer stress from blood flow

Answer 20

nitric oxide (NO)

Question 21

where is nitric oxide produced from?

Answer 21

eNOS

Question 22

nitric oxide diffuses into smooth muscle in local area and causes smooth muscle __________ or _________

Answer 22

relaxation; vasodilation

Question 23

causes vasoconstriction

Answer 23

endothelin

Question 24

causes arteriole dilation and capillary permeability

Answer 24

bradykinin, prostaglandins, and histamine

Question 25

increase or decrease in number of blood vessels can occur

Answer 25

angiogenesis

Question 26

in response to chronic ischemia, tissues release ________ factors (VEGF, FGF, etc)

Answer 26

angiogenic

Question 27

oxygen demand _____ in working muscles (exercise)

Answer 27

increases

Question 28

blood flow to tissues ________ during exercise

Answer 28

increases

Question 29

________ consumption of tissues increase during exercise

Answer 29

oxygen (VO2)

Question 30

by what mechanism is blood flow increased to exercising muscles?

Answer 30

when you exercise, you activate the SNS which causes vasoconstriction (decreased blood flow) except to the heart and brain, contracting muscle starts releasing metabolites and act on smooth muscle to vasodilate, which increases blood flow

Question 31

by what mechanism is blood flow increased to the heart?

Answer 31

when the SNS is activated, it causes vasconstriction, and the heart starts beating really fast and starts released metabolites and causes vasodilation, just like in skeletal muscle

Question 32

why does SBP increase while exercising?

Answer 32

due to an increase in CO

Question 33

who does DPB decrease while exercising?

Answer 33

due to vasodilation in skeletal muscle vasculature

Question 34

what effect does exercise have on TPR?

Answer 34

decrease it

Question 35

by what mechanism did HR increase while exercising?

Answer 35

due to an increase in the SNS an decrease in the PNS

Question 36

by what mechanism did SV increase while exercising?

Answer 36

increase in the activation of SNS and decrease in PNS will increase strength of contraction. SNS will also increase venous contraction/venous return which will increase EDV. Strength of contraction, increase respiratory pump, and increase in venous pump also increase SV

Question 37

why does SV plateau?

Answer 37

it has to do with the limited filling of the ventricle. the higher the HR, the less time for filling and relaxation. if there is less time for filling, then there is less blood and it will affect EDV and therfore, will affect SV

Question 38

what is the primary determinant of EDV?

Answer 38

TPR

Question 39

what is the primary determinant of ESV?

Answer 39

CO (cardiac output)