Textbook Ch2

Question 1

signaling sequence of the cardiac cycle

Answer 1

AP to the SA node
signal spreads through both atria
AV node - slight pause
His-Purkinje complex

Question 2

what happens/what is allowed to occur when the signal hits the AV node

Answer 2

slight pause that allows for atrial kick

Question 3

when in atrial fibrillation, what is lost and what is the significance?

Answer 3

atrial kick is lost
15-20% of cardiac output is lost due to stroke volume decreasing

Question 4

when speaking of systole and diastole, which chambers are referenced

Answer 4

ventricles contracting or ventricles relaxing

Question 5

what causes S1

Answer 5

tricuspid and mitral valve closure

Question 6

what does S1 signal?

Answer 6

onset of ventricular systole

Question 7

on the ECG, what portion is ventricular contraction

Answer 7

top of R in QRS complex

Question 8

explain isovolumetric contraction

Answer 8

ventricular muscles contract with all valves closed
- pressure increases and volume remains the same

Question 9

importance of isovolumetric contraction

Answer 9

increase the pressure in the left ventricle to overcome the pressure in the aorta

Question 10

atrial pressure increasing during isovolumetric contraction of the ventricle is due to

Answer 10

retrograde bulging of the mitral valve

Question 11

what event(s) cause(s) S2

Answer 11

aortic and pulmonary valves closing

Question 12

what terminates systole

Answer 12

aortic valve closing
- end of ventricular ejection

Question 13

what does S2 signal

Answer 13

isovolumetric relaxation in the atria

Question 14

what is diastasis

Answer 14

slow-filling phase of the ventricle that occurs after the rapid-filling phase

– lasts until atrial systole

Question 15

mechanical events related to the P Wave

Answer 15

start of P wave
– ventricles fill passively

end of P wave ends
– atria contract and contribute 15-20% of EDV

Question 16

importance of QRS complex

Answer 16

isovolumetric ventricular contraction

Question 17

when does ventricular ejection occur on an ECG

Answer 17

early portion of ST segment

Question 18

what is the significance of the T wave in QRS complex

Answer 18

repolarization of the ventricular fibers

Question 19

where is atrial repolarization found in the ECG

Answer 19

cannot be seen, but it occurs during the QRS complex

Question 21

what is the average pressure needed to open the aortic valve

Answer 21

120 mmHG

Question 22

what is CO? how to calculate

Answer 22

cardiac output

heart rate x stroke volume

Question 23

what is the average cardiac output at rest

Answer 23

4-6 L/min

Question 24

how long does it take for blood to complete systemic/pulmonary circuits

Answer 24

approx 1 min

Question 25

explain HR rising in a biochemical sense

Answer 25

epinephrine - adrenal gland norepinephrine - SNS axons -- open channels of the pacemaker cells of the SA Node and increase the rate of depolarizations and thus HR

Question 26

explain HR lowering in a biochemical sense

Answer 26

ACh released by vagus nerve endings decrease the rate of AP production at the SA node

Question 27

what sets the tone of the SA node

Answer 27

net effect of SNS and PSNS

Question 28

chronotropic effect

Answer 28

mechanisms that alter the cardiac rate increase HR = positive chronotropic decrease HR = negative chronotropic

Question 29

ionotropic effect

Answer 29

factors that affect the contractility of the myocardium

Question 30

positive ionotropic medications increase

Answer 30

contractility of the heart leading to increased cardiac output

Question 31

how do Beta Blockers effect HR of patients when exercising

Answer 31

diminished HR response myocardial receptors are unable to respond to sympathetic stimulation

Question 32

variables that regulate stroke volume

Answer 32

preload contractility afterload

Question 33

what is preload often associated with

Answer 33

end diastolic volume

Question 34

what is end diastolic volume

Answer 34

maximum amount of blood that can be in the ventricles prior to contraction

Question 35

relationship between preload and stroke volume

Answer 35

directly correlated more EDV more SV

Question 36

what is the Frank-Starling mechanism

Answer 36

explains how greater volume of the blood is ejected when more blood is returned

Question 37

preload

Answer 37

stretch/load on the myocardial wall prior to contraction -- directly influenced by end diastolic volume

Question 38

what intrinsic factors affect contractility

Answer 38

degree of myocardial stretch