Chapter 14 (Part 2)

Question 1

why would we call funny channels funny? isn’t that kind of rude?

Answer 1

no, it’s just because they let “in” K+ as well as Na+

Question 2

what molecule regulates funny channels?

Answer 2

cAMP

Question 3

don’t forget your yellow chart thing!

Answer 3

okay thank you!

Question 4

delaying repolarization delays the next contraction. the muscle contraction and relaxation time..

Answer 4

takes as long as the refractory period lasts

Question 5

why are exchangers the way they are?

Answer 5

minimizing the effect of kicking Ca out of SR and muscle cell by bringing a similar charge in

Question 6

why is the plateau phase important?

Answer 6

• creates a refractory period to delay of another action potential
• refractory period during plateau phase prevents summation or tetanus

Question 7

plateau phase: summation

Answer 7

summation would result in another immediate contraction -> rapid and shallow heart beats. refractory period prevents that.

Question 8

plateau phase: tetanus

Answer 8

sustained contraction without relaxation. this can cause the heart to miss the next AP, cardiomyocytes get out of sync, and the heart can stop beating.

Question 9

what can happen when the heart misses an AP?

Answer 9

cardiomyocytes get out of sync, and the heart can stop beating.

Question 10

ECG graph: P wave

Answer 10

generated when atria are full and SA node fires; electrical signal spreads throughout the atria causing depolarization

Question 11

ECG graph: P-Q segment

Answer 11

time it takes for an AP to travel from the SA node to the AV node

Question 12

ECG graph: QRS (2)

Answer 12

marks the firing of the AV node and depolarization of ventricles

includes depolarization of intraventricular septum, and throughout the ventricles

Question 13

ECG graph: atrial repolarization

Answer 13

occurs during the QRS segment, but its electrical activity is masked by the stronger ventricular electrical activity

Question 14

ECG graph: S to T segment

Answer 14

reflects the plateau (L-type Ca+2 channels are open) in myocardial AP

ventricles contract and pump blood out into the pulmonary and general circulation

Question 15

ECG graph: T wave

Answer 15

represents ventricular repolarization

Question 16

what does ventricular repolarization trigger ?

Answer 16

cardiac muscle relaxation

Question 17

cardiac muscle relaxation, aka

Answer 17

ventricular diastole

Question 18

cardiac muscle relaxation is triggered by

Answer 18

ventricular repolarization

Question 19

ECG graph: generated when atria are full and SA node fires; electrical signal spreads throughout the atria causing depolarization

Answer 19

ECG graph: P wave

Question 20

ECG graph: time it takes for an AP to travel from the SA node to the AV node

Answer 20

ECG graph: P-Q segment

Question 21

ECG graph: marks the firing of the AV node and depolarization of ventricles

includes depolarization of intraventricular septum, and throughout the ventricles

Answer 21

ECG graph: QRS

Question 22

ECG graph: occurs during the QRS segment, but its electrical activity is masked by the stronger ventricular electrical activity

Answer 22

ECG graph: atrial repolarization

Question 23

ECG graph: reflects the plateau (L-type Ca+2 channels are open) in myocardial AP

ventricles contract and pump blood out into the pulmonary and general circulation

Answer 23

ECG graph: S to T segment

Question 24

ECG graph: represents ventricular repolarization

Answer 24

ECG graph: T wave

Question 25

what portion of the ECG graph is affected when the heart skips a beat?

Answer 25

no QRS complex for two beats