control of cardiac output

Question 1

the cardiac output is controlled mainly by

Answer 1

the sum of all the local tissue flows

Question 2

cardiac output

Answer 2

the quantity of blood pumped into the aorta each minute

Question 3

venous return

Answer 3

the quantity of blood flowing from the veins into the right atrium each minute

Question 4

CO =

Answer 4

HR x SV

Question 5

SV =

Answer 5

EDV - ESV

Question 6

EF =

Answer 6

SF/EDV = EDV-ESV/EDV

Question 7

end diastolic volume - end systolic volume =

Answer 7

stroke volume

Question 8

which affects CO more? HR or SV?

Answer 8

HR. changes in HR alone inversely affect stroke volume

Question 9

at low HR, increase in HR is greater than

Answer 9

decrement in SV

Question 10

Bowditch (Treppe or staircase phenomenon)

Answer 10

an increase in HR will also cause positive ionotrpy duets an increase in intracellular Ca+++ with a higher HR

Question 11

preload

Answer 11

the initial stretching of the cardiac myocytes prior to contraction. it is related to the sarcomere length at the end of diastole.

Question 12

what are the indirect ways to measure preload

Answer 12

LVEDV, LVEDP, PCWP, CVP

Question 13

determinants of preload

Answer 13

venous BP, vasomotor tone, venous volume, venous retur, total blood volume, respiration, excerise, filling time (HR), ventricular compliance, atrial contraction, inflows outflow resistance, ventricular systolic failure

Question 14

Frank-Starling Mechanism

Answer 14

When venous return to the heart is increased, ventricular filling increases, as does preload. This stretching of the myocytes causes an increase in force generation, which enables the heart to eject the additional venous return and thereby increase stroke volume.
(the heart pumps the blood that is returned it)

Question 15

increasing venous return and ventricular preload leads to

Answer 15

increase in stroke volume

Question 16

Afterload is closely related to

Answer 16

aortic pressure

Question 17

afterload is

Answer 17

the “load” that the heart must eject blood against

Question 18

LaPlace’s Law is for which concept

Answer 18

after load

Question 19

what is LaPlace’s Law

Answer 19

wall stress = Pr/h. p is ventricular pressure, R is ventricular radius, h is wall thickness

Question 20

aortic pressure does what to afterload

Answer 20

increased aortic pressure increases afterload

Question 21

SVR does what to afterload

Answer 21

increased SVR increases afterload

Question 22

aortic valve stenosis effect on afterload

Answer 22

increases

Question 23

ventricular dilation effect on afterload

Answer 23

increases

Question 24

Anrep effect

Answer 24

an abrupt increase in afterload can cause a modest increase in inotropy

Question 25

contractility

Answer 25

the inherent capacity of the myocardium to contract independently of changes in afterload or preload.

Question 26

alternative name for contractility

Answer 26

iontropy

Question 27

changes in contractility are caused by

Answer 27

by intrinsic cellular mechanisms that regulate the interaction between actin and myosin independent of sarcomere length.

Question 28

decreased iontropy does what to stroke volume and LVEDP?

Answer 28

decrease SV and increases LVEDP

Question 29

increased iontropy does what to stroke volume and LVEDP

Answer 29

increase SV and decrease LVEDP

Question 30

increased afterload does what to contractility

Answer 30

increases - anrep effect

Question 31

what are the four major determinants of CO

Answer 31

contractility, stroke volume, HR, preload

Question 32

to increase stroke volume, ____ End-diastolic volume

Answer 32

increase

Question 33

to increase stroke volume ___, End-systolic volume

Answer 33

decrease

Question 34

preload is directly related to _____ because of frank starling

Answer 34

CO. preload increases, CO increases. preload decreases, CO decreases

Question 35

What physiologic relationship keeps cardiac output of the ventricle matched with venous return?

Answer 35

Frank starling mechanism – allows the heart to readily adapt to changes in venous return. Increasing venous return and preload leads to an increase in SV.

Question 36

What physiologic relationship keeps the cardiac output of the right and left ventricles matched?

Answer 36

Frank starling – outputs of the two ventricles are matched over time, otherwise blood volume would shift between the pulm and systemic circulations

Question 37

what parameter is on the y axis of starling curve

Answer 37

SV

Question 38

what parameter is on the x axis

Answer 38

LVEDP

Question 39

what factors can cause an increased after load?

Answer 39

Increased aortic pressure, increased SVR, aortic valve stenosis, ventricular dilation

Question 40

Increasing afterload ____ SV

Answer 40

decreasese

Question 41

decreasing afterload ______ sv

Answer 41

increases

Question 42

q: during the phase of rapid ventricular filling

Answer 42

mitral valve open

Question 43

q: rv preload is increased by ___ HR

Answer 43

decreased HR. more time is available for filling at reduced heart rates; therefore preload is increased.

Question 44

effect on decreased atrial contractility, decreased blood volume, and decreased ventricular compliance on preload

Answer 44

reduced ventricular filling, reduced preload

Question 45

increase in preload is a _____ in sarcomere length

Answer 45

increase

Question 46

as the preload on a ventricular myocyte is increased,

Answer 46

active tension development increases

Question 47

LVEDP is ____ by ventricular hypertrophy

Answer 47

increased

Question 48

ventricular stroke volume is ____ by decreased ionotropy

Answer 48

reduced

Question 49

ventricular stroke volume is ___ by reduced HR

Answer 49

increased - more filling

Question 50

left ventricular end-systolic volume is ___ when iontrophy is impaired

Answer 50

increased

Question 51

increasing afterload decreases ejection velocity and stroke volume, which leads to an ___ in end-systolic volume

Answer 51

increase

Question 52

an increase in end diastolic volume will ____ SV, but stroke volume changes are about 1/4 as effective in changing myocardial oxygen consumption compared to changes in HR, MAP, or ventricular radius

Answer 52

increase