12.1 B

Question 1

Sympathetic nerves have what effect on preload?

Answer 1

sympathetic firing increases preload

Question 2

Sympathetic nerves have what effect on afterload?

Answer 2

sympathetic firing increases afterload

Question 3

Sympathetic nerves have what effect on inotropic state?

Answer 3

sympathetic firing increases the inotropic state

Question 4

Increased afterload has what affect on stroke volume and cardiac output?

Answer 4

increased afterload decreases stroke volume

Question 5

What is preload?

Answer 5

• stretch on the myocardial fibers before contraction
• related to ventricular filling
• EDV, EDP, and venous return are indices of preload

Question 6

What is afterload?

Answer 6

• the ventricular wall tension during ejection
• the resistance that must be overcome to eject blood
• aortic systolic or diastolic pressure are indices

Question 7

Inotropic state represents what?

Answer 7

the force of contraction

Question 8

Inotropic state is dependent on what?

Answer 8

the cytosolic calcium level within contracting myocytes

Question 9

In contracting ventricles, cytosolic calcium levels are ____ under normal conditions.

Answer 9

submaximal, leaving room for an increase in inotropic state

Question 10

What neurotransmitter will enhance calcium entry into myocytes and increase inotropic state?

Answer 10

norepinephrine

Question 11

Starling’s law states what about the heart?

Answer 11

stroke volume increases when preload increases because stretch leads to improved force of contraction

Question 12

Starling’s law says that the increased force of contraction at greater preload is due to what?

Answer 12

stretch which results in more favorable overlap of thin and thick filaments, not a change in calcium levels

Question 13

Stretch, increases sarcomere length and does what to the force of contractino?

Answer 13

increases contraction by creating a more favorable overlap of thin and thick filaments

Question 14

What are the two determinants of preload?

Answer 14

• filling time (heart rate)

- rate of venous return (venous tone, blood volume)

Question 15

Starling’s law is best represented by a plot of what?

Answer 15

stroke volume v. EDV

Question 16

According to Starling’s law, changes in venous return or filling time will affect stroke volume by altering ____.

Answer 16

end diastolic volume

Question 17

Shifts along a single Starling curve are the result of what?

Answer 17

changes in preload due to changes in venous return or filling time

Question 18

At a given EDV, decreased afterload results in what change in stroke volume?

Answer 18

it will increase the stroke volume

Question 19

What might be a cause of change in afterload that shifts the Starling curve up or down?

Answer 19

changes in systemic arterial pressure

Question 20

An increase in systemic arterial pressure will have what affect on a Starling curve?

Answer 20

it will shift the whole Starling curve downward

Question 21

What are two major determinants of afterload?

Answer 21

• change in TPR due to changes in arteriolar tone

- aortic stenosis

Question 22

Aortic stenosis is seen as what change of a Starling curve?

Answer 22

aortic valve stenosis leads to hypertrophy and an increased force, increasing the peak pressure in the ventricle, increasing afterload and shifting the Starling curve downward

Question 23

An increase in inotropic state will have what effect on a Starling curve?

Answer 23

increased inotropic state will shift the curve upward

Question 24

A beta blocker will have what effect on a starling curve?

Answer 24

it will decrease the inotropic state and shift the curve downward

Question 25

What is the effect of cardiac glycosides on the inotropic state?

Answer 25

they inhibit Na/K pump, increasing intracellular sodium levels, activating the Na/Ca exchanger, increasing intracellular calcium levels, increasing inotropic state

Question 26

What are some things that would increase inotropy?

Answer 26

sympathetic firing, a beta agonist, cardiac glycosides

Question 27

WWhat are some things that would decrease inotropy?

Answer 27

• decreased sympathetic nerve firing to heart
• a beta antagonist
• a calcium blocker
• heart failuer

Question 28

On a typical Starling curve, an increase in inotropic state can’t be differentiated from a change in what other factor?

Answer 28

afterload

Question 29

In order to differentiate a change in afterload from a change in inotropic state, what modification must be made to a Starling curve?

Answer 29

EDV must be plotted against stroke work instead of against stroke volume

Question 30

What is stroke work?

Answer 30

an estimate of stroke volume times MAP

Question 31

Plotting stroke work against EDV, makes the Starling curve independent of what variable?

Answer 31

afterload

Question 32

What is the Starling reserve?

Answer 32

the maximal increase in stroke volume that can be achieved by increasing EDV

Question 33

What is the Inotropic reserve?

Answer 33

the maximal increase in stroke volume that can be achieved by increasing inotropic state

Question 34

What is the total cardiac reserve?

Answer 34

the sum of the inotropic and starling reserves