Repolarization, plateau, and repolarization

Question 1

What is the cause and duration of rapid depolarization? What does it end with

Answer 1

Cause- N+ entry
Duration: 3-5 mcsec

Ends with- closure of voltage-gated fast sodium channels

Question 2

What is the cause and duration of the plateau? What does it end with?

Answer 2

Cause: Ca2+ entry
Duration: ∼175 msec
Ends with: Closure of slow calcium-channels

Question 3

What is the cause and duration of repolarization? What does it end with?

Answer 3

Cause: K+ loss
Duration: 75 msec
Ends with: Closure -of slow potassium-channels

Question 4

Refractory period is what?

Answer 4

periods where the cell is less able to respond to another stimulus. Conducting system provides
Stimulus for an action potential. Refractory= stubborn will not respond to another stimulus in this period. Could respond if stimulus
Were strong enough.

Question 5

AP in skeletal muscles passes membrane
And enters the cell via________.Contraction
Is sightly after the action potential

Answer 5

t-tubules.

Question 6

Length of cardiac action potential in ventricular cell is what_________. This is _______than skeletal muscle fiber. Long refractory period prevents____ and ___

Answer 6

Timing of Refractory Periods
Length of cardiac action potential in ventricular cell
250–300 msec
30 times longer than skeletal muscle fiber
Long refractory period prevents summation and tetany

Question 7

In skeletal muscles, the fast-twitch fiber compae with the amount of time required for the development of tension is

Answer 7

very short

Question 8

Skeletal muscles that are stimulated repeatedly will exhibit ____ and ______

Answer 8

summation and tetanus

Question 9

In the cardiac muscle fiber, the refractory period lasts how long?

Answer 9

as long as the entire muscle twitch

Question 10

What prevents tetanus in the cardiac muscle?

Answer 10

long refractory period

Question 11

What triggers the contraction of heart and is built in system?

Answer 11

Conducting system

Question 12

A system of specialized cardiac muscle cells
Initiates and distributes electrical impulses that stimulate contraction

Answer 12

conducting system

Question 13

what is automaticity?

Answer 13

When cardiac muscle tissue contracts automatically

Question 14

Sinoatrial (SA) node=

Answer 14

cardiac pacemaker connected to AV modes(internodal
Pathways)

Question 15

aka bundle of HISS: , left and right bundle branches that run along the interventricular septum

Answer 15

AV bundle

Question 16

part of the heart that gets thinner and spreads

Answer 16

Bundle branched

Question 17

Refractory period in the skeletal muscle vs the cardiac muscle

Answer 17

Skeletal muscle- refractory period is shorter than muscle twitch which means summation that causes tetanus.

cardiac muscle- refractory period is the same time length as the muscle twitch, so there is no tetanus