Question 1

Which vessel is responsible for delivering oxygenated blood to the coronary capillary beds?

Accepted Answer

Coronary arteries

Question 2

The anterior interventricular artery supplies which regions of the heart?

Accepted Answer

Interventricular septum and anterior ventricular walls

Question 3

Which cardiac vein primarily drains the posterior left ventricle?

Accepted Answer

Middle cardiac vein

Question 4

A blockage in the right marginal artery would most directly affect blood supply to which region?

Accepted Answer

Right atrium and most of right ventricle

Question 5

Which structure collects deoxygenated blood from the cardiac veins and drains it into the right atrium?

Accepted Answer

Coronary sinus

Question 6

During a myocardial infarction, which process occurs in the affected heart tissue?

Accepted Answer

Death of tissue due to interrupted blood supply

Question 7

Which imaging technique is used to visualize coronary arteries by injecting dye through the systemic circuit?

Accepted Answer

Percutaneous coronary angiography

Question 8

What is the primary function of desmosomes within intercalated discs of cardiac muscle cells?

Accepted Answer

Hold cells together and prevent separation during contraction

Question 9

Which cellular structure is most likely impaired if electrical signals fail to spread efficiently between cardiac muscle cells, resulting in asynchronous contraction?

Accepted Answer

Gap junctions within intercalated discs

Question 10

Which statement best describes the automaticity of cardiac muscle cells?

Accepted Answer

Cardiac muscle cells can spontaneously depolarize and set their own rhythm

Question 11

Why can tetanic contractions not occur in cardiac muscle?

Accepted Answer

Absolute refractory period is much longer than in skeletal muscle fibers

Question 12

Which process is triggered by the influx of Ca$$^{2+}$$ from extracellular fluid in cardiac muscle cells?

Accepted Answer

Release of Ca$$^{2+}$$ from the sarcoplasmic reticulum

Question 13

What percentage of Ca$$^{2+}$$ needed for cardiac muscle contraction comes from extracellular sources?

Accepted Answer

$$80-90\%$$

Question 14

Which of the following is a key difference between skeletal and cardiac muscle regarding contraction?

Accepted Answer

Cardiac muscle contracts as a unit (functional syncytium), skeletal muscle contracts independently

Question 15

A patient presents with angina pectoris. What is the underlying cause of this symptom?

Accepted Answer

Reduced oxygen supply to the myocardium (myocardial ischemia)

Question 16

Which of the following best explains why cardiac muscle is more resistant to fatigue than skeletal muscle?

Accepted Answer

Cardiac muscle cells have numerous large mitochondria, making up about $$35\% of $$cell volume

Question 17

Which branch of the left coronary artery supplies the left atrium and posterior wall of the left ventricle?

Accepted Answer

Circumflex artery

Question 18

Which of the following statements about the sarcoplasmic reticulum (SR) in cardiac muscle is correct?

Accepted Answer

SR in cardiac muscle is simpler and lacks triads

Question 19

Which of the following is TRUE regarding pacemaker cells in the heart?

Accepted Answer

They rhythmically and spontaneously depolarize to generate action potentials

Question 20

If the gap junctions within intercalated discs are destroyed, what would be the most likely consequence for heart function?

Accepted Answer

Loss of coordinated contraction, leading to reduced pumping efficiency

Coronary Circulation and Cardiac Muscle: Structure, Function, and Comparison with Skeletal Muscle

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