Question 1

Which of the following best explains the phenomenon of 'wave summation' in skeletal muscle physiology?

Accepted Answer

It is the addition of one twitch to another when a second stimulus arrives before the relaxation phase has ended, resulting in a more powerful contraction.

Question 2

A patient presents with muscle weakness and laboratory tests reveal elevated levels of creatine kinase (CK) in the blood. What does this most likely indicate?

Accepted Answer

The patient has experienced muscle or nerve tissue damage.

Question 3

During the contraction cycle, what is the direct result of ATP binding to the myosin head?

Accepted Answer

The myosin head detaches from the active site on actin.

Question 4

Which of the following correctly describes the role of the sarcoplasmic reticulum (SR) in muscle contraction?

Accepted Answer

It stores and releases calcium ions necessary for contraction.

Question 5

A muscle is stimulated to contract, but the tension produced never exceeds the load and the muscle does not change length. What type of contraction is this?

Accepted Answer

Isometric contraction

Question 6

Which of the following best describes the sliding filament theory?

Accepted Answer

Muscle contraction occurs when actin and myosin filaments slide past each other, shortening the sarcomere without changing the length of the filaments.

Question 7

Which of the following events occurs FIRST at the neuromuscular junction to initiate muscle contraction?

Accepted Answer

An action potential arrives at the axon terminal of the motor neuron.

Question 8

A muscle fiber is observed to have a high concentration of myoglobin, many mitochondria, and is resistant to fatigue. Which type of muscle fiber is this?

Accepted Answer

Slow fiber

Question 9

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

Accepted Answer

It binds calcium ions, causing a conformational change that moves tropomyosin and exposes active sites on actin.

Question 10

A person is performing a biceps curl. As the biceps brachii shortens to lift the weight, which type of contraction is occurring?

Accepted Answer

Isotonic concentric contraction

Question 11

Which of the following is TRUE regarding the length-tension relationship in skeletal muscle?

Accepted Answer

Tension produced by a muscle fiber depends on the length of individual sarcomeres at the time of stimulation.

Question 12

Which of the following best describes the function of creatine phosphate in muscle cells?

Accepted Answer

It acts as a reservoir of high-energy phosphate to rapidly regenerate ATP from ADP during short bursts of activity.

Question 13

A muscle fiber is unable to relax between rapid stimuli and maintains a sustained contraction with no visible relaxation phase. What is this condition called?

Accepted Answer

Complete tetanus

Question 14

Which of the following statements about the Z line in a sarcomere is correct?

Accepted Answer

It is where thin filaments are anchored.

Question 15

During intense exercise, when oxygen is limited, which metabolic pathway is primarily used by skeletal muscle fibers to generate ATP?

Accepted Answer

Anaerobic glycolysis

Question 16

Which of the following best describes the function of the transverse tubules (T tubules) in skeletal muscle fibers?

Accepted Answer

They conduct action potentials from the sarcolemma deep into the muscle fiber.

Question 17

A patient is unable to perform plantar flexion of the foot. Which muscle is most likely impaired?

Accepted Answer

Gastrocnemius

Question 18

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

Accepted Answer

They possess intercalated discs with gap junctions and desmosomes.

Question 19

Which of the following best describes the process of muscle hypertrophy?

Accepted Answer

Increase in the size of existing muscle fibers due to enlargement of their component cells.

Question 20

A person is standing on their toes, raising their heels off the ground. Which movement is being performed at the ankle joint?

Accepted Answer

Plantar flexion

Skeletal, Cardiac, and Smooth Muscle: Structure, Function, and Physiology

Guida di studio - Domande di pratica

Study guide - Flashcard