Question 1

Which of the following best explains why cardiac muscle cannot achieve tetanus, unlike skeletal muscle?

Accepted Answer

Cardiac muscle cells have an extra-long refractory period, ensuring relaxation before the next contraction.

Question 2

What is the primary function of intercalated discs in cardiac muscle tissue?

Accepted Answer

They physically and electrically connect myocardial cells, allowing coordinated contraction.

Question 3

Which of the following statements about nuclei in muscle cells is correct?

Accepted Answer

Cardiac muscle cells usually have one nucleus per cell.

Question 4

A patient presents with excess fluid in the pericardial cavity. What is the most likely consequence if this condition is not treated?

Accepted Answer

Restriction of heart movement, potentially leading to cardiac tamponade.

Question 5

Which structure prevents the prolapse of atrioventricular (AV) valves during ventricular contraction?

Accepted Answer

Chordae tendinae attached to papillary muscles.

Question 6

Why is the left side of the heart more muscular than the right side?

Accepted Answer

It pumps blood to the systemic circuit, which requires higher pressure to reach all body tissues.

Question 7

Which of the following is the correct sequence of electrical conduction in the heart?

Accepted Answer

SA node → AV node → Bundle branches → Purkinje fibers

Question 8

Which of the following best describes the role of gap junctions in cardiac muscle?

Accepted Answer

They allow electrical coupling between myocardial cells for synchronized contraction.

Question 9

What is the second-messenger signaling molecule for muscle contraction in cardiac muscle?

Accepted Answer

Calcium ions ($$Ca^{2+})$$

Question 10

Which of the following is true regarding the initiation of contraction in cardiac muscle compared to skeletal muscle?

Accepted Answer

Cardiac muscle contraction is autonomic and autorhythmic, while skeletal muscle is voluntary.

Question 11

A patient has a mutation that disrupts the formation of desmosomes in cardiac muscle cells. Which of the following is the most likely consequence?

Accepted Answer

Weakened physical connection between myocardial cells, increasing risk of tissue rupture.

Question 12

Which of the following equations best represents the relationship between pressure, flow, and resistance in the cardiovascular system?

Accepted Answer

$$P = F 	imes R$$

Question 13

During ventricular systole, which valves are open and which are closed?

Accepted Answer

Semilunar valves open, AV valves closed

Question 14

Which of the following best explains the importance of the long refractory period in cardiac muscle cells?

Accepted Answer

It prevents tetanus, ensuring the heart can relax and refill with blood between beats.

Question 15

Which anatomical location is the heart found in?

Accepted Answer

Mediastinum

Question 16

Which of the following is a unique feature of cardiac muscle compared to skeletal muscle?

Accepted Answer

Presence of intercalated discs

Question 17

If the SA node fails to function, which structure typically takes over as the pacemaker of the heart?

Accepted Answer

AV node

Question 18

Which of the following best describes the role of mitochondria in cardiac muscle cells?

Accepted Answer

They are very abundant, supplying the high energy demand of continuous contraction.

Question 19

Which of the following is the correct description of the systemic circuit in the cardiovascular system?

Accepted Answer

It carries blood from the heart to the body and back.

Question 20

Which of the following best explains why the heart is considered myogenic?

Accepted Answer

It generates its own action potentials without external stimulation.

Cardiac Muscle and Heart Anatomy: Structure, Function, and Physiology

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