$$ \text{Myosin-ADP-Pi} + \text{Actin} \rightarrow \text{Power Stroke} $$

Question 1

Which of the following best describes the hierarchical organization of muscle structure from largest to smallest?

Accepted Answer

Muscle, fascicle, muscle fiber, myofibril, sarcomere

Question 2

A patient is unable to generate sufficient muscle force during voluntary contraction. Which of the following mechanisms is most likely impaired?

Accepted Answer

Recruitment of motor units

Question 3

During muscle contraction, which bands of the sarcomere change length?

Accepted Answer

I band shortens, H zone disappears

Question 4

Which equation best represents the cross-bridge cycle in muscle contraction?

Accepted Answer

$$ 	ext{Myosin-ADP-Pi} + 	ext{Actin} ightarrow 	ext{Power Stroke} $$

Question 5

Excitation-contraction coupling in skeletal muscle involves which sequence of events?

Accepted Answer

Release of calcium from the sarcoplasmic reticulum, binding to troponin, movement of tropomyosin, cross-bridge formation

Question 6

Which of the following best explains the length-tension relationship in striated muscle?

Accepted Answer

Muscle tension is highest at intermediate sarcomere lengths due to optimal overlap of actin and myosin

Question 7

Creatine phosphate serves which primary function in muscle physiology?

Accepted Answer

Provides a rapid source of ATP during the initial seconds of intense muscle activity

Question 8

Which type of skeletal muscle fiber is most resistant to fatigue?

Accepted Answer

Type I (slow oxidative)

Question 9

A sudden stretch of a muscle activates which reflex, and what is the role of gamma motor neurons in this process?

Accepted Answer

Monosynaptic stretch reflex; gamma motor neurons adjust sensitivity of muscle spindles

Question 10

Which of the following best describes the function of Golgi tendon organs?

Accepted Answer

Monitor tension in tendons and inhibit muscle contraction to prevent damage

Question 11

Reciprocal innervation in skeletal muscles ensures that:

Accepted Answer

Agonist muscles contract while antagonist muscles relax

Question 12

During voluntary muscle contraction, which motor neurons are responsible for activating extrafusal muscle fibers?

Accepted Answer

Alpha motor neurons

Question 13

Which pathway best describes the neural circuit of a simple reflex arc?

Accepted Answer

Sensory neuron → motor neuron

Question 14

Cardiac muscle differs from skeletal muscle in which of the following ways?

Accepted Answer

Cardiac muscle contracts rhythmically and is regulated by pacemaker cells

Question 15

Smooth muscle contraction is primarily regulated by which mechanism?

Accepted Answer

Phosphorylation of myosin light chains by myosin light chain kinase (MLCK)

Question 16

Which equation best represents the initial ATP regeneration in muscle cells during intense activity?

Accepted Answer

$$ 	ext{Creatine phosphate} + 	ext{ADP} ightarrow 	ext{Creatine} + 	ext{ATP} $$

Question 17

A patient presents with muscle fatigue after repeated contractions. Which physiological change is most likely responsible?

Accepted Answer

Accumulation of lactic acid and depletion of ATP

Question 18

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

Accepted Answer

Ability to maintain contraction for long periods with minimal energy

Question 19

Which of the following best explains the role of alpha and gamma motor neurons during voluntary movement?

Accepted Answer

Alpha motor neurons activate extrafusal fibers; gamma motor neurons adjust spindle sensitivity

Question 20

Which of the following best describes the sliding filament theory of muscle contraction?

Accepted Answer

Actin filaments slide past myosin filaments, shortening the sarcomere

Physio Exam 1 Study Guide Part 2

Study Guide - Practice Questions