Q: A patient has a stroke volume of 70 mL and a heart rate of 80 beats per minute. What is their cardiac output?

$$CO = 70 \times 80 = 5600 mL/$$min

Question 1

Which of the following best describes the role of troponin in skeletal muscle contraction?

Accepted Answer

Troponin binds to calcium ions, causing a conformational change that exposes myosin binding sites on actin.

Question 2

During the cardiac cycle, which event is responsible for the first heart sound (S1)?

Accepted Answer

Closure of the atrioventricular valves at the onset of ventricular systole.

Question 3

A patient presents with muscle weakness. Laboratory tests reveal low levels of acetylcholine at the neuromuscular junction. Which step in muscle contraction is most directly affected?

Accepted Answer

Generation of the end-plate potential leading to muscle fiber excitation.

Question 4

Which formula correctly represents cardiac output ($$CO) in $$terms of heart rate ($$HR) $$and stroke volume ($$SV$$)?

Accepted Answer

$$CO = HR 	imes SV$$

Question 5

Which of the following best explains why increasing the frequency of stimulation can lead to tetanus in skeletal muscle fibers?

Accepted Answer

It prevents calcium from being pumped back into the sarcoplasmic reticulum, maintaining high cytosolic calcium.

Question 6

Which pressure is defined as the difference between systolic and diastolic blood pressure?

Accepted Answer

Pulse pressure ($$PP)$$

Question 7

A patient has a stroke volume of 70 mL and a heart rate of 80 beats per minute. What is their cardiac output?

Accepted Answer

$$CO = 70 	imes 80 = 5600 mL/$$min

Question 8

Which of the following is NOT a function of erythrocytes?

Accepted Answer

Initiating the coagulation cascade during hemostasis.

Question 9

Which of the following best describes the Frank-Starling law of the heart?

Accepted Answer

The greater the stretch of cardiac muscle fibers, the greater the force of contraction.

Question 10

Which of the following events occurs during the plateau phase of the cardiac action potential?

Accepted Answer

Influx of calcium ions through voltage-gated channels.

Question 11

Which of the following best describes the function of platelets in hemostasis?

Accepted Answer

They adhere to damaged blood vessels and release factors that promote clot formation.

Question 12

Which equation correctly calculates mean arterial pressure ($$MAP) $$using systolic ($$SBP) $$and diastolic ($$DBP) $$blood pressure?

Accepted Answer

$$MAP = DBP + \frac{1}{3}(SBP - DBP)$$

Question 13

Which of the following is a correct sequence of events in the excitation-contraction coupling of skeletal muscle?

Accepted Answer

Release of acetylcholine → depolarization of sarcolemma → release of calcium from sarcoplasmic reticulum → binding of calcium to troponin

Question 14

Which of the following best explains the difference between isotonic and isometric muscle contractions?

Accepted Answer

Isotonic contractions involve movement of a load, while isometric contractions involve tension development without movement.

Question 15

Which of the following is a function of the capillaries in the circulatory system?

Accepted Answer

Exchanging nutrients, gases, and wastes between blood and tissues.

Question 16

A patient has a hematocrit of 60%. Which of the following is the most likely consequence?

Accepted Answer

Increased blood viscosity and risk of thrombosis.

Question 17

Which of the following best describes the role of the sinoatrial (SA) node in the heart?

Accepted Answer

It initiates the electrical impulse that sets the pace for the heart rate.

Question 18

Which of the following is a correct description of the role of myosin in muscle contraction?

Accepted Answer

Myosin binds to actin and uses energy from ATP hydrolysis to perform the power stroke.

Question 19

Which of the following best explains the effect of increased preload on stroke volume?

Accepted Answer

Increased preload increases stroke volume by stretching cardiac muscle fibers, enhancing contraction.

BIOL 2420 Study Guide: Muscle, Cardiovascular, and Blood Physiology

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