$$ATP \rightarrow ADP + P_i + \text{energy}$$

Question 1

Which connective tissue layer directly surrounds individual skeletal muscle fibers?

Accepted Answer

Endomysium

Question 2

What is the primary function of the neuromuscular junction?

Accepted Answer

To transmit action potentials from a motor neuron to a muscle fiber

Question 3

During the cross-bridge cycle, what event directly causes the power stroke?

Accepted Answer

Release of ADP and inorganic phosphate ($$P_i) $$from the myosin head

Question 4

Which protein blocks the myosin binding sites on actin in a relaxed muscle?

Accepted Answer

Tropomyosin

Question 5

What triggers the release of calcium ions from the sarcoplasmic reticulum during muscle contraction?

Accepted Answer

Depolarization of the T-tubules by an action potential

Question 6

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

Accepted Answer

Thin filaments slide past thick filaments, shortening the sarcomere

Question 7

A patient presents with muscle weakness after a nerve injury. Which structure is most likely affected?

Accepted Answer

Neuromuscular junction

Question 8

Which of the following is NOT a function of skeletal muscle?

Accepted Answer

Production of hormones

Question 9

What is the role of acetylcholinesterase at the neuromuscular junction?

Accepted Answer

It breaks down acetylcholine, terminating the signal

Question 10

Which equation best represents the hydrolysis of ATP during the cross-bridge cycle?

Accepted Answer

$$ATP ightarrow ADP + P_i + 	ext{energy}$$

Question 11

Which structure is the functional contractile unit of a skeletal muscle fiber?

Accepted Answer

Sarcomere

Question 12

If a muscle cell is unable to remove calcium ions from the cytosol, what is the most likely result?

Accepted Answer

The muscle will remain contracted (tetany)

Question 13

Which of the following best explains why ATP is required for muscle relaxation?

Accepted Answer

ATP binds to myosin, causing it to release from actin

Question 14

Which of the following is TRUE regarding the action potential in skeletal muscle fibers?

Accepted Answer

It is generated by the influx of sodium ions through voltage-gated channels

Question 15

A muscle fiber is stretched beyond its optimal sarcomere length. What is the expected effect on tension generation?

Accepted Answer

Tension decreases due to reduced overlap of actin and myosin

Question 16

Which of the following events occurs FIRST during excitation-contraction coupling?

Accepted Answer

Depolarization of the T-tubule membrane

Question 17

Which of the following is a correct sequence of events in the cross-bridge cycle?

Accepted Answer

Cross-bridge attachment, power stroke, cross-bridge detachment, resetting myosin head

Question 18

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

Accepted Answer

Troponin binds calcium, causing tropomyosin to move and expose myosin binding sites on actin

Question 19

Which of the following is TRUE regarding the structure of a myofibril?

Accepted Answer

It contains both thick (myosin) and thin (actin) filaments

Question 20

A patient with compartment syndrome is most likely experiencing increased pressure in which anatomical structure?

Accepted Answer

Within a muscle compartment surrounded by connective tissue

Lecture #19

Guida di studio - Domande di pratica