Chapter 19 Deck 3 Slide 43+

Question 1

the nodal cells do not have a stable rmp what is there rmp?

Answer 1

-60 millivolts

Question 2

what are specific voltage-gated channels associated with nodal cells?

Answer 2

slow voltage-gated na+ channels, fast voltage-gated Ca2+ channels, voltage-gated K+ channels

Question 3

what are the electrical events at the SA node that initiate action potential?

Answer 3

1) slow gated Na+ channel opens allowing Na+ to leak in. membrane potential changes from -60 to -40mV
2) fast voltage-gated Ca2+ channels open allowing Ca2+ to flow in. -40 to 0mV
3) K+ channels open allowing K+ to flow out and repolarize

Question 4

uninhibited by vagal tone the heart would beat how many times per minute?

Answer 4

100

Question 5

at rest the SA node action potentials are how far apart?

Answer 5

.8 seconds

Question 6

what membrane protein of the SA node plays a critical role in repolarizing?

Answer 6

voltage-gated K channels

Question 7

after threshold is reached at the sinoatrial node what membrane protein plays a critical role in depolarization?

Answer 7

fast voltage-gated calcium channels

Question 8

in the sinoatrial node what membrane protein is critical for reaching threshold?

Answer 8

slow voltage-gated sodium Channels

Question 9

what is the term for the inhibition of the SA node by parasympathetic activity related by the vagus nerve?

Answer 9

vagal tone

Question 10

unlike neurons nodal cells do not have a stable rmp comma they exhibit a pacemaker potential when their?

Answer 10

Na+ channels open ( slow voltage-gated)

Question 11

in neurons, action potential depolarization is from_____ entry, and in nodal cells depolarization is from _____ entry

Answer 11

Na+ entry, Ca2+ entry

Question 12

how does an action potential spread through the heart?

Answer 12

1) SA node - AV node
2) delay at AV - AV bundle
3) AV bundle - left and right bundle branches
- bundle branches - purkinje fibers
4) spread throughout ventricles by gap junctions

Question 13

action potentials are spread from pre kinji fibers throughout the Heart by what kind of Junctions?

Answer 13

Gap Junctions

Question 14

where is the action potential delayed when it is spreading throughout the heart?

Answer 14

atrioventricular node

Question 15

after an action potential is delayed at the atrioventricular node it then continues to the?

Answer 15

atrioventricular bundle then two left and right bundle branches and purkinje fibers

Question 16

what are the events of cardiac muscle action potential?

Answer 16

1) depolarization - fast voltage-gated Na+ open
2) plateau- slow voltage-gated Ca2+ and K open
3) repolarization- voltage-gated K+ remain open

Question 17

what are the changes in millivolts that occur during cardiac muscle action potential?

Answer 17

1) from RMP -90 to +30
2) plateau mV remain at +30
3) repolarization +30 to -90

Question 18

what are special channels associated with cardiac muscle?

Answer 18

1) fast voltage-gated Na channel
2) slow voltage-gated Ca2 channels
3) voltage-gated K+ channels

Question 19

what is an ectopic pacemaker?

Answer 19

a pacemaker other than the SA node

Question 20

if Ave vinodh becomes default when SA node impaired how many beats per minute?

Answer 20

40 to 50 beats minute fast enough to sustain life

Question 21

what is the rate of beats per minute that cardiac muscle alone can maintain?

Answer 21

20 to 40 beats per minute usually too slow to maintain life

Question 22

what are some common membrane proteins that cardiac muscle cells have?

Answer 22

sodium potassium pumps, calcium pumps, sodium and potassium leak channels

Question 23

what is the resting membrane potential of cardiac muscle cell at rest?

Answer 23

-90 millivolts

Question 24

what is the resting memory potential nodal cells?

Answer 24

-60 millivolts

Question 25

in the sinoatrial node what channels are open during pacemaker potential

Answer 25

sodium channels flow in -60 millivolts to -40 millivolts threshold voltage

Question 26

chaotic electrical activity in ventricles uncoordinated contraction and pump failure leads to death of heart cells, treated with paddle electrode defibrillator

Answer 26

ventricular fibrillation

Question 27

chaotic timing of atrial action potentials

Answer 27

atrial fibrillation

Question 28

results from stress, stimulants, or sleep deprivation. Abnormal action potential within AV node or ventricles. Not then trumental and less occurring in large numbers.

Answer 28

premature ventricular contractions