Question 1

Which of the following best describes the function of the sarcoplasmic reticulum in skeletal muscle fibers?

Accepted Answer

It stores and releases calcium ions ($$\mathrm{Ca$$^{2+}$$}) $$necessary for muscle contraction.

Question 2

During the sliding filament theory of muscle contraction, which two molecules are essential for cross-bridge formation and sarcomere shortening?

Accepted Answer

ATP and $$\mathrm{Ca$$^{2+}$$}$$

Question 3

A patient is experiencing muscle weakness due to a defect in the acetylcholine receptor at the neuromuscular junction. Which of the following best explains the physiological consequence?

Accepted Answer

The muscle fiber will not depolarize, preventing action potential generation and contraction.

Question 4

Which of the following statements about motor units is correct?

Accepted Answer

Muscle fibers of a motor unit are spread out throughout the muscle, allowing for graded contraction.

Question 5

Which period of a muscle twitch is characterized by cross-bridge formation and sarcomere shortening?

Accepted Answer

Contraction period

Question 6

If the frequency of action potentials delivered to a motor unit increases, what is the most likely effect on muscle contraction?

Accepted Answer

Muscle contraction becomes smoother due to temporal summation.

Question 7

According to the size principle, which motor units are recruited first when lifting a light load?

Accepted Answer

Small, highly excitable motor units

Question 8

Which of the following correctly describes the flow of blood through the heart and body?

Accepted Answer

Right atrium → right ventricle → pulmonary artery → lungs → pulmonary vein → left atrium → left ventricle → aorta → body tissues → vena cava → right atrium

Question 9

Which phase of the cardiac action potential in contractile cells is responsible for the plateau, and which ion is primarily involved?

Accepted Answer

Plateau phase; $$\mathrm{Ca$$^{2+}$$}$$ influx through voltage-gated calcium channels

Question 10

If the SA node fails, which structure typically takes over as the pacemaker of the heart, and what is the expected effect on heart rate?

Accepted Answer

AV node; heart rate decreases

Question 11

Which equation correctly represents cardiac output ($$CO) $$and stroke volume ($$SV$$)?

Accepted Answer

$$CO = SV 	imes HR$$

Question 12

A patient has an end diastolic volume ($$EDV) of 120 mL $$and an end systolic volume ($$ESV) of 50 mL. $$What is their stroke volume ($$SV$$)?

Accepted Answer

$$SV = EDV - ESV = 120\,\mathrm{mL} - 50\,\mathrm{mL} = 70\,\mathrm{mL}$$

Question 13

According to the Frank-Starling law, what happens to cardiac output if venous return increases?

Accepted Answer

Cardiac output increases due to increased stroke volume.

Question 14

Which formula correctly represents mean arterial pressure ($$MAP$$)?

Accepted Answer

$$MAP = \frac{1}{3} 	imes (	ext{Systolic Pressure} - 	ext{Diastolic Pressure}) + 	ext{Diastolic Pressure}$$

Question 15

Which of the following best explains why blood pressure drops as blood flows from arteries to capillaries and then to veins?

Accepted Answer

Resistance increases as vessel diameter decreases, causing pressure to drop.

Question 16

Which adrenergic receptor is primarily responsible for vasoconstriction of arterioles during sympathetic stimulation?

Accepted Answer

Alpha-1 ($$\$$alpha_1$$) adrenergic receptor

Question 17

A sudden increase in blood pressure activates baroreceptors. What is the immediate effect on the sympathetic nervous system and blood vessels?

Accepted Answer

Sympathetic activity decreases, causing vasodilation and reduced cardiac output.

Question 18

Which of the following is a short-term mechanism for correcting low blood pressure?

Accepted Answer

Activation of the sympathetic nervous system increases heart rate and vasoconstriction.

Muscle, Cardiovascular, and Blood Pressure Physiology: Study Guide

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