Q: Which of the following is the correct formula for calculating cardiac output?

$$Cardiac\ Output = Stroke\ Volume \times Heart\ Rate$$

Question 1

Which of the following best describes the primary difference between skeletal and cardiac muscle in terms of control and structure?

Accepted Answer

Skeletal muscle is voluntary and striated, while cardiac muscle is involuntary and striated.

Question 2

A patient presents with muscle fatigue after intense exercise. Which energy system is most likely depleted first during the initial seconds of maximal muscle contraction?

Accepted Answer

Creatine phosphate

Question 3

Which of the following is the correct sequence of events in the sliding filament theory of muscle contraction?

Accepted Answer

Calcium binds to troponin, tropomyosin moves, myosin binds actin, power stroke occurs

Question 4

Which of the following best explains why cardiac muscle cells can contract in a coordinated fashion without direct neural stimulation?

Accepted Answer

They contain intercalated discs with gap junctions that allow electrical impulses to spread rapidly.

Question 5

A patient’s ECG shows a prolonged QRS complex. Which of the following is most likely affected?

Accepted Answer

Ventricular depolarization

Question 6

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

Accepted Answer

Ability to contract without neural input

Question 7

During a muscle twitch, which phase corresponds to the time when calcium ions are actively transported back into the sarcoplasmic reticulum?

Accepted Answer

Relaxation period

Question 8

Which of the following best describes the role of the T-tubules in skeletal muscle contraction?

Accepted Answer

They transmit action potentials deep into the muscle fiber.

Question 9

A patient with a mutation in the gene encoding for troponin would most likely experience which of the following symptoms?

Accepted Answer

Impaired regulation of muscle contraction due to disrupted calcium binding

Question 10

Which of the following best explains why fast-twitch muscle fibers fatigue more quickly than slow-twitch fibers?

Accepted Answer

Fast-twitch fibers rely primarily on anaerobic metabolism, which produces less ATP per glucose molecule.

Question 11

Which of the following is the correct formula for calculating cardiac output?

Accepted Answer

$$Cardiac\ Output = Stroke\ Volume 	imes Heart\ Rate$$

Question 12

Which of the following best describes the effect of sympathetic stimulation on the heart?

Accepted Answer

Increases heart rate and force of contraction

Question 13

A patient is diagnosed with a blockage in the left bundle branch. Which part of the heart’s conduction system is directly affected?

Accepted Answer

Bundle branches

Question 14

Which of the following best explains why smooth muscle can maintain contraction for long periods with minimal energy expenditure?

Accepted Answer

Smooth muscle uses the latch-bridge mechanism to maintain tension.

Question 15

Which of the following is the correct order of events in the cardiac cycle?

Accepted Answer

Atrial contraction, ventricular contraction, ventricular relaxation, atrial relaxation

Question 16

Which of the following best describes the role of calcium ions in muscle contraction?

Accepted Answer

Calcium ions bind to troponin, causing tropomyosin to move and expose binding sites on actin.

Question 17

A patient with hyperkalemia (elevated blood potassium) is at risk for which of the following cardiac problems?

Accepted Answer

Arrhythmias due to altered membrane potential

Question 18

Which of the following is the correct formula for the force generated by a muscle, given cross-sectional area and specific tension?

Accepted Answer

$$Force = Cross	ext{-}Sectional\ Area 	imes Specific\ Tension$$

Question 19

Which of the following best explains why the refractory period in cardiac muscle is longer than in skeletal muscle?

Accepted Answer

It prevents tetanus and allows the heart to refill with blood between contractions.

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