Autorhythmicity

Question 1

what are the major phases of SA node AP

Answer 1

prepotential
depolarization
repolarization

Question 2

what happens during the prepotential phase of SA node AP generation?

Answer 2

a small number of Na+ channels open
v-gated K+ channels that opened in repolarization phases are closing
v-gated Ca++ channels are beginning to open

Question 3

in which phase of SA node AP generation do v-gated Ca++ channels begin to open?

Answer 3

prepotential

Question 4

in which phase of SA node AP generation do a small number of NA+ channels open?

Answer 4

prepotential

Question 5

what happens during the depolarization phase of SA node AP generation?

Answer 5

v-gated Ca++ channels are open

v-gated K+ channels are closed

Question 6

during which phase of SA node AP generation are all v-gated Ca++ channels open and v-gated K+ channels are closed?

Answer 6

depolarization

Question 7

what happens during the repolarization phase of AP generation in the SA node?

Answer 7

v-gated Ca++ channels close

v-gated K+ channels open

Question 8

in which phased of AP generation of the SA node are all v-gated K+ channels open and Ca++ channels closed?

Answer 8

repolarization phase

Question 9

how long does the AP generation cycle of the SA node take?

Answer 9

about 300 ms

Question 10

during SA node AP generation, when do Ca++channels begin to open?

Answer 10

prepotential, all open in depolarization

Question 11

during SA node AP generation, when do Ca++ channels close?

Answer 11

repolarization

Question 12

during SA node AP generation when do K+ channels open?

Answer 12

repolarization

Question 13

during SA node AP generation when do K+ channels close?

Answer 13

begin to close during prepotential, totally closed during depolarization

Question 14

when do Na++ channels open in SA node AP generation?

Answer 14

prepotential

Question 15

what is the absolute refractory period for cardiac muscle cells?

Answer 15

a period of time when cardiac muscle cells are completely insensitive to any further stimulation

Question 16

what is the relative refractory period for cardiac muscle cells?

Answer 16

a period of time when cardiac muscle cells exhibit reduced sensitivity to additional stimulation

Question 17

what is the fn of the long refractory period of cardiac muscle cells

Answer 17

prevents tetanic cntx

Question 18

what is an ECG?

Answer 18

an electrocardiogram

records the electrical events in the myocardium

Question 19

what does a HCP do when they interpret an ECG?

Answer 19

correlate the recorded electreical events with the mechanical events of the cardiac cycle

Question 20

what is the P wave of an ECG?

Answer 20

depolarization of atrial myocardium

Question 21

what does the P wave of an ECG correlate to?

Answer 21

onset of atrial cntx

Question 22

what is the QRS complex of an ECG?

Answer 22

depolarization of the ventricle

simultaneous repolarization of the atria

Question 23

what does the QRS complex of an ECG correlate to?

Answer 23

onset of ventricular cntx

Question 24

what is the T wave of an ECG?

Answer 24

repolarization of ventricles

Question 25

what does the T wave of an ECG correlate to?

Answer 25

relaxation of ventricle

Question 26

during which interval does the atria contract and begin to relax and the ventricle contracts?

Answer 26

PQ interval

Question 27

during which interval does the ventricle contract and begin to relax?

Answer 27

QT interval

Question 28

draw and label an ECG P-T

Answer 28

do it

Question 29

on an ECG, where do the atria depolarize?

Answer 29

P wave

Question 30

on an ECG, where do the ventricles depolarize?

Answer 30

QRS complex

Question 31

on and ECG, where do the atria repolarize?

Answer 31

QRS complex

Question 32

on an ECG, where do the ventricles repolarize?

Answer 32

T wave

Question 33

what is the PQ interval?

Answer 33

the period during which the atria contract and begin to relax and the ventricles begin to contract

Question 34

what is the QT interval?

Answer 34

the period during which the ventricles contract and begin to relax