Cardiac Muscle

Question 1

What does “Ca2+-induced Ca2+release” refers to in cardiac muscle cells?
A. Ca2+ entry from ECF stimulates Ca2+ release from SR
B. Ca2+ release from SR induces Ca2+ entry from ECF
C. Ca2+ re-uptake by the SR after contraction
D. Ca2+ exit from the cell after contraction
E. Ca2+ released from SR stimulated Ca2+ exit from cell

Answer 1

A

Question 2

Which of the following is NOT true about action potentials in myocardial contractile cells?
A. Depolarization is due to entry of sodium to cell
B. Repolarization is due to potassium exiting cell
C. Action potentials are long in comparison to other cells
D. Action potentials can overlap
E. A second action potential cannot be triggered during refractory period

Answer 2

D

Question 3

How is cardiac muscle and smooth muscle similar?
A. Presence of sarcomeres
B. Controlled by somatic motor neurons
C. Electrical link between cells allowing coordinated contraction
D. Multinucleated
E. Myosin Light Chain Kinase (MLCK) is important for binding of myosin and actin

Answer 3

C

Question 4

What causes depolarization in auto rhythmic cardiac cells?
A. Opening of sodium channels
B. Opening of calcium channels
C. Closing of sodium channels
D. Closing of calcium channels
E. Opening of potassium channels

Answer 4

B

Question 5

What is the stable membrane potential of cardiac contractile cells?
A. -90mV
B. -70mV
C. -55mV
D. +20mV
E. +30mV

Answer 5

A