Question 1

Which property of skeletal muscle tissue allows it to return to its original length after being stretched?

Accepted Answer

Elasticity

Question 2

During the sliding filament theory, what happens to the sarcomere when a muscle contracts?

Accepted Answer

The sarcomere shortens as thin filaments slide past thick filaments

Question 3

A resting membrane potential for a skeletal muscle fiber is typically about $$-90\ \mathrm{mV}. $$What does this value indicate about the distribution of ions?

Accepted Answer

There are more negative ions inside the cell than outside

Question 4

Which event directly triggers the opening of voltage-gated calcium channels in the sarcoplasmic reticulum during excitation-contraction coupling?

Accepted Answer

Depolarization of the T-tubule membrane

Question 5

What is the role of acetylcholinesterase at the neuromuscular junction?

Accepted Answer

It degrades acetylcholine in the synaptic cleft, ending muscle stimulation

Question 6

Which process is responsible for the passive return of calcium ions into the sarcoplasmic reticulum during muscle relaxation?

Accepted Answer

Active transport by calcium pumps

Question 7

A muscle fiber is stimulated 80-100 times per second, generating sustained contraction with no time for relaxation. What is this phenomenon called?

Accepted Answer

Fused (complete) tetanus

Question 8

Which equation correctly represents the reaction catalyzed by creatine kinase for immediate ATP regeneration in muscle?

Accepted Answer

$$\mathrm{CP} + \mathrm{ADP} \rightarrow \mathrm{ATP} + \mathrm{creatine}$$

Question 9

Which phase of a muscle twitch is characterized by the time required for calcium ions to be actively pumped back into the sarcoplasmic reticulum?

Accepted Answer

Relaxation period

Question 10

What is the primary source of ATP during long-duration, low-intensity muscle activity such as maintaining posture?

Accepted Answer

Aerobic catabolism (oxidative phosphorylation)

Question 11

Which type of skeletal muscle fiber is best suited for rapid, powerful contractions but fatigues quickly?

Accepted Answer

Type II (fast-twitch)

Question 12

If the sarcomere is overly stretched prior to contraction, what is the expected effect on muscle tension?

Accepted Answer

Tension is reduced because fewer crossbridges can form

Question 13

Which of the following best describes the refractory period in a muscle fiber?

Accepted Answer

The time after contraction when the muscle fiber cannot respond to another stimulus

Question 14

What is the effect of acetylcholine binding to its receptor on the motor end plate?

Accepted Answer

It opens ligand-gated sodium channels, leading to depolarization

Question 15

Which process is responsible for the generation of an action potential in a muscle fiber?

Accepted Answer

Opening and closing of gated sodium (Na+) and potassium (K+) channels

Question 16

During muscle contraction, what is the function of troponin?

Accepted Answer

It binds calcium ions and moves tropomyosin to expose active sites on actin

Question 17

Which metabolic pathway produces the most ATP per glucose molecule in muscle cells?

Accepted Answer

Aerobic catabolism (oxidative phosphorylation)

Question 18

A patient experiences involuntary, forceful muscle contractions that do not relax. What is the most likely explanation?

Accepted Answer

Spasm due to inability of muscle to relax

Question 19

Which of the following best describes the process of wave summation in muscle fibers?

Accepted Answer

Multiple stimuli cause progressively greater tension as calcium ions accumulate

Question 20

Which of the following is TRUE regarding the role of myoglobin in muscle cells?

Accepted Answer

It binds oxygen, allowing muscles to sustain activity for longer periods

Chapter 10

Guida di studio - Domande di pratica

Study guide - Flashcard