Cardiac Muscles

Question 1

Relies on BOTH intracellular and extracellular calcium

Answer 1

Cardiac Muscle

Question 2

d.t. Na influx

Answer 2

PHASE 0

Question 3

Brief period of REPOlarization

d.t. K efflux and decrease in Na influx

Answer 3

PHASE 1 (Partial Repolarization)

Question 4

PLATEAU of AP

d.t. Ca influx

Answer 4

PHASE 2

Question 5

Repolarization

Decreased Calcium influx and increased K efflux

Answer 5

PHASE 3 (Complete Repolarization)

Question 6

Resting Membrane Potential

Answer 6

PHASE 4

Question 7

Increase Intracellular Calcium

Answer 7

L type or Slow Calcium Channel: Major and Voltage gated

T type or Fast Calcium Channel

Question 8

Decrease Intracellular Calcium

Answer 8

3 Na 1Ca Countertransport

Ca ATPase pump

Question 9

Begins at the upstroke of the action potential and ends after the plateau

No action potential can be INITIATED

Answer 9

Absolute Refractory Period (ARP)

Question 10

Longer than ARP
Conducted AP cannot be elicited
No AP can be propagated

Answer 10

Effective Refractory Period (ERP)

Question 11

Occurs after ARP

AP is possible but will require more than usual inward current

Answer 11

Relative Refractory Period (RRP)

Question 12

SA Node AP

Slow Na influx towards the threshold

Answer 12

PHASE 4 (unstable RMP)

not constant
pwede iincrease or idecrease
If channel

SYMPA - (+) Beta sa SA node –> INCREASED HR

PARA - (+) M2 sa SA node –> DECREASED HR

Question 13

SA Node AP

Ca INFLUX (DEPOLARIZATION)

Answer 13

PHASE 0

Question 14

SA Node AP

K EFFLUX (repolarization)

Answer 14

PHASE 3

autorhythmicity
self excitation

opening of K channels in P3 –> triggers opening of If channels (Phase 4)

phase 3 always followed by phase 4