$$3\text{Na}^+ \rightarrow \text{out},\ 2\text{K}^+ \rightarrow \text{in}$$

Question 1

Which of the following best describes the role of the sodium-potassium pump in maintaining the resting membrane potential of a skeletal muscle cell?

Accepted Answer

It moves 3 Na⁺ out of the cell and 2 K⁺ in, using ATP.

Question 2

During a biceps curl, which muscle acts as the agonist and which as the antagonist?

Accepted Answer

Biceps brachii is the agonist; triceps brachii is the antagonist.

Question 3

A patient is unable to raise their eyebrows. Which muscle is most likely affected?

Accepted Answer

Frontalis

Question 4

Which of the following statements about the sliding filament theory is correct?

Accepted Answer

Actin slides over myosin, causing the sarcomere to shorten.

Question 5

Which lever class is most common in the human body, and what is its arrangement?

Accepted Answer

3rd class; fulcrum-effort-load

Question 6

During muscle contraction, which event directly exposes the binding sites on actin?

Accepted Answer

Calcium binds to troponin

Question 7

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

Accepted Answer

Elasticity

Question 8

A sprinter experiences muscle fatigue after a short burst of activity. Which ATP source is primarily used during this period?

Accepted Answer

Creatine phosphate

Question 9

Which muscle is responsible for plantar flexion of the foot?

Accepted Answer

Gastrocnemius

Question 10

If a muscle fiber is held at a constant length while generating force, which type of contraction is occurring?

Accepted Answer

Isometric

Question 11

Which sequence correctly describes the events at the neuromuscular junction leading to muscle contraction?

Accepted Answer

Nerve impulse → ACh released → ACh binds receptors → Na⁺ enters → Action potential → Contraction

Question 12

Which muscle type is striated, involuntary, and typically has 1-2 nuclei per cell?

Accepted Answer

Cardiac muscle

Question 13

A patient presents with difficulty flexing their elbow. Which muscle is most likely impaired?

Accepted Answer

Biceps brachii

Question 14

Which of the following best describes the resting membrane potential of a muscle cell?

Accepted Answer

High K⁺ inside, negative inside

Question 15

During the contraction cycle, what is the role of ATP?

Accepted Answer

ATP releases myosin from actin and recocks the myosin head

Question 16

Which muscle is primarily responsible for abducting the arm at the shoulder?

Accepted Answer

Deltoid

Question 17

Which filament is considered the thick filament in the sarcomere?

Accepted Answer

Myosin

Question 18

A person is holding a dumbbell steady without moving their arm. Which type of contraction is occurring, and which muscle property allows this?

Accepted Answer

Isometric contraction; excitability

Question 19

Which equation represents the action of the sodium-potassium pump in muscle cells?

Accepted Answer

$$3	ext{Na}^+ ightarrow 	ext{out},\ 2	ext{K}^+ ightarrow 	ext{in}$$

Question 20

Which sequence correctly represents the hierarchical organization of skeletal muscle from largest to smallest?

Accepted Answer

Muscle → Fascicle → Muscle Fiber → Myofibril → Sarcomere → Filaments

Skeletal Muscles and Muscle Tissue: Study Notes (Chapters 9 & 10)

Study Guide - Practice Questions