Lecture 6: Cardiac Muscle Tissue

Question 1

Which of the following characteristics would be true of cardiac muscle cells, but not skeletal muscle fibers?

A. cells have sarcomeric banded pattern
B. cells utilize T-tubules
C. cells are mononucleated
D. cells utilize ryanodine channels

Answer 1

C. cells are mononucleated

Question 2

The resting potential of -85 mV is characteristic of which of the following phases of cardiac fast action potential?

A. Phase 1
B. Phase 2
C. Phase 3
D. Phase 4

Answer 2

D. Phase 4

Question 3

During which phase of cardiac fast action potential does rapid depolarization occur?

Answer 3

Phase 0

Question 4

During which phase of cardiac fast action potential does initial, incomplete repolarization occur?

Answer 4

Phase 1

Question 5

During which phase of cardiac fast action potential does plateau or slow decline of membrane potential occur?

Answer 5

Phase 2

Question 6

During which phase of cardiac fast action potential does rapid repolarization occur?

Answer 6

Phase 3

Question 7

The sodium-calcium exchanger in the sarcolemma of the cardiac muscle cell is an example of which of the following mechanisms?

A. Primary active transport involving an antiporter
B. Primary active transport involving a symporter
C. Secondary active transport involving a symporter
D. Secondary active transport involving an antiporter

Answer 7

D. Secondary active transport involving an antiporter

Question 8

Left ventricular isovolumic contraction occurs immediately following which of the following events?

A. Closure of the aortic valve
B. Opening of the aortic valve
C. Closure of the AV valve
D. Opening of the AV valve

Answer 8

C. Closure of the AV valve

Question 9

Which of the following statements is true for the period of rapid ejection?

A. Occurs when left ventricular pressure is above 80 mmHg
B. Semilunar valves are closed during this phase
C. Occurs during last 2/3 of ejection
D. It results in ejection of about 90% of total volume of blood

Answer 9

A. Occurs when left ventricular pressure is above 80 mmHg

Question 10

Stroke volume output can be increased by which of the following mechanisms?

A. Decreasing EDV
B. Increasing EDV
C. Increasing ESV
D. Decreasing EDV and increasing ESV

Answer 10

B. Increasing EDV