cardiovascular lecture 6

Question 1

when a hemorrhage occurs, does stroke volume increase, decrease or stay the same?

Answer 1

decreases –> eventually, SNS will kick in and activate beta receptors in the atria to increase the stroke volume

Question 2

when a hemorrhage occurs, does heart rate increase, decrease or stay the same?

Answer 2

stays the same –> shortly after hemorrhage, SNS act on beta receptors in atria (through funny channels) to increase heart rate

Question 3

when a hemorrhage occurs, does CO increase, decrease or stay the same?

Answer 3

decreases –> vasoconstriction via sympathetic stimulation of alpha receptors will increase CO shortly after

Question 4

when a hemorrhage occurs, does TPR increase, decrease, or stay the same

Answer 4

stays the same –> increases shortly after through compensatory response

Question 5

when a hemorrhage occurs, does MAP increase, decrease or stay the same?

Answer 5

decreases

Question 6

when loss of blood causes an immediate reduction in MAP, what happens?

Answer 6

compensatory responses in CO and TPR act quickly to restore MAP

Question 7

at the capillary level, reduced MAP causes what

Answer 7

increased absorption and reduced filtration to help “protect” blood volume

Question 8

describe fluid shifts after a hemorrhage

Answer 8

18h after hemorrhage, there is a loss of erythrocytes but an increase in plasma volume –> this increase is due to increased absorption at the capillary level to maintain blood volume

Question 9

list the causes of hypotension

Answer 9

1. hemorrhage
2. allergic response: histamine release –> vasodilation = decrease TPR and thus MAP
3. emotional stress: decrease symp, increase parasymp = decrease HR, SV, CO, TPR and MAP
4. decreased CO (myocardial infarction)
5. fluid loss (salts/water): diarrhea or vomitting

Question 10

what is shock

Answer 10

any situation in which a decrease in blood flow to the organs and tissues damages them ie hypovolemic, low-resistance, cardiogenic

Question 11

describe the skeletal pump mechanism

Answer 11

helps to return venous blood to the heart and opposes the buildup of excessive lymphatic fluid

Question 12

dynamic adjustments in blood flow distribution during exercise result from changes in what

Answer 12

changes in CO and changes in regional vasodilation and vasoconstriction. there is a decrease in peripheral resistance

Question 13

during exercise, an increase in CO is due to what

Answer 13

a large increase and HR and a smaller increase in SV –> CO increases much more than TPR decreases so MAP overall increases slightly

Question 14

during exercise, what do brain “exercise centers” do to baroreceptors

Answer 14

it resets them upward

Question 15

what is (VO2 max)

Answer 15

maximal oxygen consumption –> as exercise intensity increases, oxygen consumption increases until reaching a point where it fails to rise despite a further increment in workload

Question 16

what can limit VO2max

Answer 16

1. CO
2. respiratory system’s ability to deliver oxygen
3. exercising muscle’s ability to use oxygen
   * *except for highly trained athletes, CO is the factor that determines VO2max

Question 17

what does hypertension do to systemic arterial blood pressure

Answer 17

chronically increases it

Question 18

what are the ramifications of hypertension

Answer 18

left ventricular hypertrophy or stroke

Question 19

what is heart failure

Answer 19

when the heart fails to pump an adequate CO

Question 20

what is diastolic dysfunction

Answer 20

reduced ventricular compliance results in an increased end-diastolic pressure leading to a decreased end-diastolic volume and a decreased SV

Question 21

what is systolic dysfunction

Answer 21

a decrease in cardiac contractility –> a lower SV at any given end-diastolic volume

Question 22

what are the ramifications of heart failure

Answer 22

less rapid discharge of afferent baroreceptors –> increased HR and TPR and fluid retention (pulmonary edema)

Question 23

to increase SV, _______ increases contractility by changing _______

Answer 23

sympathetic stimulation; Ca channels

Question 24

to increase SV, _______ increases EDV by acting on _______

Answer 24

Frank Starling; funny channels

Question 25

is it possible, under normal circumstances, to increase one determinant of CO (HR or SV) without increasing the other

Answer 25

No!