Green- Cardiac Muscle

Question 1

Phases 0-3 when cardiac muscle cells cannot be restimulated; also called absolute refractory period

Answer 1

Effective refractory period

Question 2

Fast response action potential occurs in

Answer 2

Atrial and ventricular cells

Question 3

Increasing the length of the cardiac sarcomere increases the force of contraction

Answer 3

Frank-starling law

Question 4

Na current that initiates the action potential in a pacemaker cell

Answer 4

Funny current

Question 5

Regulation of contraction either positively or negatively

Answer 5

Inotropy

Question 6

Mechanical connection of fascia adherens and desmosomes that keeps cardiac cells from pulling apart

Answer 6

Intercalated disc

Question 7

Protein in the SR that regulates calcium uptake by the SR

Answer 7

Phospholamban

Question 8

Increased stretching of cardiac muscles prior to contraction

Answer 8

Preload

Question 9

Phases 3-4 when action potential can be generated with a strong stimulus

Answer 9

Relative refractory period

Question 10

Slow response action potentials occur in

Answer 10

Pacemaker cells

Question 11

Resting potential. 
Sodium and calcium channels closed
Potassium channels (inward rectifying) open.
Higher exctracellular [Na}
Higher Intracellular [K]

Answer 11

Phase 4

Question 12

Partial repolarization due to effflux of potassium through transient outward channels and
Inactivation of sodium channels

Answer 12

Phase 1

Question 13

L-type Ca channels open and remain open.
Potassium channels close
Plateau phase.
Calcium ions trigger internal Ca release from SR

Answer 13

Phase 2

Question 14

K exits thru delayed rectifier channels

K efflux exceed Ca influx

Ca channels close.

Soon becomes all potassium efflux

Repolarizes back to resting potential

Answer 14

Phase 3

Question 15

Ion concentrations returned to normal

Na removed by Na/K ATPase

Ca removed by Na-Ca exchanger and Ca pump

Answer 15

Phase 4

Question 16

In pacemaker cells, the resting potential is _______ compared to atrial ventricular cells

Answer 16

Less negative

Question 17

The refractory period in cardiac cells is due to ?

Answer 17

The inactivation of fast sodium channels.

Question 18

Fast sodium channels open during which phase?

Answer 18

Phase 0

Question 19

During phase ____ of action potential, calcium enters cell through L-Type channels in t-tubules and sarcolemma

Answer 19

2

Question 20

When does calcium influx end in cardiac muscle cells?

Answer 20

Starting at the end of phase 2 and going into phase 3

Question 21

When phospholamban is phosphorylated, SERCA is _____-

Answer 21

More active at uptakee

Question 22

Ventricular cells are ______ than atrial cells to cholinergic stimulation (parasympathetic nervous system, decrease heart rate)

Answer 22

Less sensitive

Question 23

Stimulation of beta-adrenergic receptors increases contractility by?

Answer 23

Increasing the activity of L-type calcium channels

Question 24

Stretching the heart ______ sensitivity to calcium, allowing for stronger contraction

Answer 24

Increases