the heart

Question 1

what are the three layers of the heart protect the pericardial cavity?

Answer 1

• endocardium (lining of the chambers)
• myocardium (the muscle)
• epicardium

Question 2

what is cardiac output?

Answer 2

volume of blood pumped by each ventricle in one minute

Question 3

what is cardiac reserve?

Answer 3

difference between resting and maximal cardiac output

Question 4

what seperates the right and left side of the heart?

Answer 4

the septum

Question 5

which side of the heart has a thicker wall and why?

Answer 5

the left side because blood is pumped at much higher pressure becuase the systemetic circulation is much longer than the pulmonary circulation

Question 6

why are atrial walls thin?

Answer 6

as the blood falls into the ventricles by gravity so requires a lot less strength

Question 7

what are the names of the four valves of the heart?

Answer 7

• pulmonary valve
• aortic valve
• mitral valve
• tricuspid valve

Question 8

which valve sepetates the right atrium from the right ventricle?

Answer 8

tricuspid valve

Question 9

which valve sepetates the right ventricle from the lung?

Answer 9

pulmonary valve

Question 10

which valve seperates the left atrium from the left ventricle?

Answer 10

mitral valve

Question 11

which valve seperates the left ventricle from the body?

Answer 11

aortic valve

Question 12

what tendons are connected to the atrioventricular valves?

Answer 12

chordae tendineae

Question 13

what muscles are connected to tendons in the heart?

Answer 13

papillary muscle

Question 14

when do the heart muscles connected to valves contract?

Answer 14

during systole, preventing them from inverting

Question 15

what are the heart sounds called?

Answer 15

S1 and S2

Question 16

what is S1 associated with?

Answer 16

closing of the AV valves at the start of ventricular systole

Question 17

what is S2 associated with?

Answer 17

closing of the semilunar valves at the end of the ventricular systole

Question 18

what can be found in the I band of sarcomeres in cardiac muscle?

Answer 18

the thin filaments (actin)

Question 19

what can be found in the A band of sarcomeres in cardiac muscle?

Answer 19

thick (myosin) and thin filaments (where they overlap)

Question 20

what is muscle contraction triggered by?

Answer 20

Ca2+

Question 21

at rest, what proteins prevent actin and myosin from interacting?

Answer 21

• troponin
• tropomyosin

Question 22

what protein does calcium bind to causing conformational changes in tropomyosin?

Answer 22

troponin

Question 23

what are the stages of the cardiac cycle?

Answer 23

1. atrial contraction
2. isovolumetric contraction (ventricular pressure rises rapidly without volume change)
3. rapid ejection (blood flows rapidly from ventricles into arteries)
4. reduced ejection (ventricle repolarises and tension reduces)
5. isovolumetric relaxation (ventricular pressure decreases but volume stays the same)
6. rapid filling
7. reduced filling

Question 24

what is the state of the valves during atrial contraction?

Answer 24

• valves between atria and ventricles open
• semilunar valves closed

Question 25

what is the state of the valves during isovolumetric contraction?

Answer 25

- all valves closed

Question 26

what is the state of the valves during rapid ejection?

Answer 26

- AV valves closed - semilunar valves open

Question 27

what is the state of the valves during isovolumetric relaxation?

Answer 27

- all valves closed

Question 28

what is the state of the valves during rapid filling?

Answer 28

- AV valves are open - semilunar valves closed

Question 29

what is membrane potential determined by?

Answer 29

1. Concentration gradients for Na+, K+ and Ca2+ 2. Their permeability (electrical conductance) 3. Electrogenic ion pumps

Question 30

how does the Na+/K+ ATPase (3Na+/2K+) pump contribute to the charge inside the cell?

Answer 30

net negative charge inside cell

Question 31

how does the Ca2+ -ATPase pump contribute to the charge inside the cell?

Answer 31

net negative charge inside cell

Question 32

how does the Na+/Ca2+ exchanger (3Na+/1Ca2+) pump contribute to the charge inside the cell?

Answer 32

net positive charge inside cell

Question 33

inotropy

Answer 33

strength of contraction

Question 34

chronotropy

Answer 34

contraction frequency

Question 35

dromotropy

Answer 35

velocity of signal conduction by cardiomyocytes

Question 36

lusitropy

Answer 36

myocardial relaxation

Question 37

bathmotropy

Answer 37

myocardial excitability

Question 38

what are the effects of sympathetic stimulation?

Answer 38

* Ventricular pressure rises more rapidly to a higher systolic pressure * Ejection fraction is increased * Diastolic volume falls * Stroke volume increases * Duration of systole decreases