Cardiac output

Question 1

volume of blood pumped from each ventricle per unit time (L/min)

Answer 1

cardiac output (CO)

Question 2

vol of blood ejected from each ventricle during each heartbeat (L/beat)

Answer 2

stroke volume

Question 3

what determines the intrinsic rhythm of the heart? what is it usually?

Answer 3

SA node; 100 ap/ 100 b/min

Question 4

the SA node is innervated by neurons, what are they called and what do they consist of?

Answer 4

autonomic motor neurons; sympathetic and parasympathetic neurons

Question 5

how do sympathetic neurons act on SA node?

Answer 5

increase action potential production

Question 6

how do parasympathetic neurons act on SA node?

Answer 6

decrease action potential production

Question 7

what kind of effect do the neurons create in the SA node by increasing and decreasing ap?

Answer 7

chromotropic effects

Question 8

how do sympathetic neurons act on pacemaker potential duration?

Answer 8

decrease duration

Question 9

how do parasympathetic neurons act on pacemaker potential duration?

Answer 9

increase duration

Question 10

increases permeability of f and t type channels, causes membrane to reach threshold faster

Answer 10

sympathetic stimulation

Question 11

increases K+ ion channel permeability, hyperpolarizing the membrane, making it take longer to reach threshold. Also inhibit t type channels

Answer 11

parasympathetic stimulation

Question 12

what is it called when the neurons affect action potential propagation thru conducting cells?

Answer 12

dromotropic effects

Question 13

how do sympathetic neurons affect ap propagation speed? thru which conducting cells?

Answer 13

increases propagation speed thru all cells, ap spread faster

Question 14

how do parasympathetic neurons affect ap propagation speed? thru which conducting cells?

Answer 14

slows propagation speed; only internodal and AV nodal propagation

Question 15

what does stroke volume depend on?

Answer 15

contraction force

Question 16

what is contraction force dependent on?

Answer 16

preload, contractility, and afterload

Question 17

vol of blood in a ventricle at the end of diastole

Answer 17

preload / end-diastolic vol EDV

Question 18

what is preload determined by?

Answer 18

venous return

Question 19

opposite of cardiac output; amount of blood entering the heart per unit time

Answer 19

venous return

Question 20

how are stroke vol and preload related? what is it called?

Answer 20

as preload increases, stroke vol also increases; Frank-starling mechanism

Question 21

increases calcium ion release from SR, increases affinity of troponin C for Ca+, decreases distance bw thick and thin filaments

Answer 21

stretching of the heart muscle

Question 22

strength of contraction at any given preload

Answer 22

contractility

Question 23

what kind of neurons do contractile cells have?

Answer 23

sympathetic neurons

Question 24

how is contractility quantified? what is it at usually?

Answer 24

ejection fraction (EF) ; 50-75%

Question 25

how hard the heart must work to eject blood

Answer 25

afterload

Question 26

afterload is a function of what?

Answer 26

arterial pressure

Question 27

afterload has an inverse relationship with what?

Answer 27

stroke vol; as afterload increases, SV decreases

Question 28

what do the ventricles open?

Answer 28

semilunar valves