Skeletal Muscle: Structure, Function, and Clinical Relevance

Question 1

Which component of a skeletal muscle is the fundamental unit of contraction?

Accepted Answer

Sarcomere

Answer

Myofilament

Answer

Myofibril

Answer

Fascicle

Question 2

Which neurotransmitter is primarily released at the neuromuscular junction, facilitating muscle contraction?

Accepted Answer

Acetylcholine

Answer

Norepinephrine

Answer

GABA

Answer

Dopamine

Question 3

Which protein filament forms the thin filaments in skeletal muscle?

Accepted Answer

Actin

Answer

Myosin

Answer

Tropomyosin

Answer

Troponin

Question 4

Which type of connective tissue surrounds individual muscle fibers?

Accepted Answer

Endomysium

Answer

Perimysium

Answer

Epimysium

Answer

Mesomysium

Question 5

What is the primary role of satellite cells in skeletal muscle?

Accepted Answer

Muscle fiber growth and repair

Answer

Neurotransmitter synthesis

Answer

Energy storage

Answer

Contraction initiation

Question 6

Which histological staining technique is commonly used to visualize skeletal muscle striations?

Accepted Answer

Hematoxylin and eosin

Answer

Trichrome

Answer

Periodic acid-Schiff

Answer

Immunohistochemistry

Question 7

At the neuromuscular junction, which neurotransmitter is primarily released by motor neurons?

Accepted Answer

Acetylcholine

Answer

Dopamine

Answer

Glutamate

Answer

GABA

Question 8

Which muscle fiber type is known for sustaining prolonged, low-force contractions?

Accepted Answer

Type I

Answer

Type IIa

Answer

Type IIb

Answer

Type III

Question 9

Which histological stain is commonly employed to visualize the striations present in skeletal muscle?

Accepted Answer

Hematoxylin and eosin

Answer

Periodic acid-Schiff

Answer

Trichrome

Answer

Oil Red O

Question 10

The sarcoplasmic reticulum is responsible for:

Accepted Answer

Calcium release

Answer

Energy storage

Answer

Protein synthesis

Answer

Mitochondrial respiration

Question 11

What is the primary function of satellite cells in skeletal muscle?

Accepted Answer

Muscle repair

Answer

Muscle contraction

Answer

Energy storage

Answer

Ion transport

Question 12

The specialized junction formed between adjacent muscle fibers, allowing for coordinated contraction, is called:

Accepted Answer

Gap junction

Answer

Desmosome

Answer

Adherens junction

Answer

Hemidesmosome

Question 13

What is a hallmark clinical feature of myasthenia gravis?

Accepted Answer

Muscle weakness and fatigability

Answer

Muscle enlargement

Answer

Muscle discomfort

Question 14

Which characteristic is essential for an optimal mounting medium used in the preservation and sectioning of skeletal muscle tissue?

Accepted Answer

Mechanical support

Answer

Enhanced staining intensity

Answer

Complete tissue dehydration

Answer

Elimination of autofluorescence

Question 15

Identify the protein complex responsible for the contraction of skeletal muscle.

Accepted Answer

Actin-myosin

Answer

Troponin-tropomyosin

Answer

Dystrophin-sarcoglycan

Answer

Ryanodine receptor-DHPR complex

Question 16

Specify the primary function of the sarcoplasmic reticulum.

Accepted Answer

Storage and release of calcium ions

Answer

Glucose metabolism

Answer

Generation of energy

Answer

Protein synthesis

Question 17

Determine the type of nerve fiber that innervates skeletal muscle.

Accepted Answer

Alpha-motor neuron

Answer

Beta-motor neuron

Answer

Gamma-motor neuron

Answer

Delta-motor neuron

Question 18

Explain the function of the neuromuscular junction.

Accepted Answer

Transmission of electrical impulses from motor neurons to skeletal muscle fibers

Answer

Regulation of muscle fiber metabolism

Answer

Anchoring muscle fibers to connective tissue

Answer

Synthesis of muscle proteins

Question 19

Identify the primary energy source for skeletal muscle contraction.

Accepted Answer

ATP

Answer

Glycogen

Answer

Creatine phosphate

Answer

Fat

Question 20

Which of the following is NOT a structural component of the sarcomere?

Accepted Answer

T tubule

Answer

A band

Answer

H zone

Answer

I band

Question 21

Which of the following is the primary role of mitochondria in the context of skeletal muscle?

Accepted Answer

Energy production via oxidative phosphorylation

Answer

Calcium storage

Answer

Myoglobin storage

Answer

Protein synthesis

Question 22

Which muscle fiber type is characterized by high oxidative capacity and is best suited for sustained, low-intensity activities?

Accepted Answer

Type I

Answer

Type IIa

Answer

Type IIb

Answer

Type IIx

Question 23

What is the key function of the neuromuscular junction?

Accepted Answer

Site of neurotransmitter release from motor neurons

Answer

Location of muscle fiber depolarization

Answer

Point of attachment between myofibrils

Answer

Site of calcium ion release

Question 24

Which of the following is NOT a known cause of muscular dystrophy?

Accepted Answer

Natural aging process

Answer

Genetic mutations in cytoskeletal proteins

Answer

Immune system attack on muscle fibers

Answer

Nutritional deficiencies

Question 25

What is the primary role of satellite cells in skeletal muscle?

Accepted Answer

Muscle repair and regeneration

Answer

Myoglobin storage

Answer

Neurotransmitter release

Answer

Muscle fiber contraction

Question 26

Which protein, when bound to calcium ions, initiates muscle contraction by binding to actin?

Accepted Answer

Troponin

Answer

Tropomyosin

Answer

Myosin

Answer

Actin

Question 27

The repeating unit of skeletal muscle, containing all the necessary components for contraction, is known as the:

Accepted Answer

Sarcomere

Answer

Myofibril

Answer

Muscle fiber

Answer

Myofilament

Question 28

The neuromuscular junction is where:

Accepted Answer

Motor neurons stimulate muscle fibers to contract

Answer

Muscle fibers release neurotransmitters to stimulate motor neurons

Answer

Sensory neurons detect changes in muscle length

Answer

Hormones bind to receptors on muscle fibers

Question 29

The neurotransmitter that is released at the neuromuscular junction to trigger muscle contraction is:

Accepted Answer

Acetylcholine

Answer

Epinephrine

Answer

Serotonin

Answer

Dopamine

Question 30

Type I muscle fibers are characterized by:

Accepted Answer

High endurance and oxidative metabolism

Answer

Fast contraction and anaerobic metabolism

Answer

Intermediate contraction speed and fatigue resistance

Answer

Slow contraction and high force generation

Question 31

Muscle regeneration primarily occurs through:

Accepted Answer

Formation and fusion of satellite cells

Answer

Division of existing muscle fibers

Answer

Stem cell transplantation

Answer

Replacement by connective tissue

Question 32

Which condition is characterized by progressive muscle weakness and degeneration?

Accepted Answer

Muscular dystrophy

Answer

Myasthenia gravis

Answer

Parkinson's disease

Answer

Multiple sclerosis

Question 33

The Golgi tendon organ primarily senses and responds to:

Accepted Answer

Muscle tension

Answer

Muscle length

Answer

Joint position

Answer

Painful stimuli

Question 34

Electron microscopy is particularly useful for studying muscle tissue because it provides:

Accepted Answer

High-resolution images of cellular ultrastructure

Answer

Three-dimensional reconstructions of muscle fibers

Answer

Real-time visualization of muscle contraction

Answer

Quantification of muscle fiber cross-sectional area

Question 35

A group of muscle fibers innervated by a single motor neuron is known as a:

Accepted Answer

Motor unit

Answer

Myofibril

Answer

Sarcomere

Answer

Fascicle

Question 36

What is the smallest functional unit of contraction in skeletal muscle?

Accepted Answer

Sarcomere

Answer

Myofibril

Answer

Myofilament

Answer

Myosin head

Question 37

Which protein filament forms the 'thick' bands in a sarcomere?

Accepted Answer

Myosin

Answer

Actin

Answer

Tropomyosin

Answer

Titin

Question 38

How do calcium ions initiate muscle contraction?

Accepted Answer

By binding to troponin, exposing myosin-binding sites

Answer

By stimulating the release of acetylcholine

Answer

By directly causing the movement of myofilaments

Answer

By providing energy for contraction

Question 39

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

Accepted Answer

Hormone release

Answer

Movement

Answer

Heat production

Answer

Posture maintenance

Question 40

What is the name of the connective tissue layer that immediately surrounds each muscle fiber?

Accepted Answer

Endomysium

Answer

Perimysium

Answer

Epimysium

Answer

Tendon

Question 41

Which type of muscle contraction occurs when the muscle shortens and moves a load?

Accepted Answer

Isotonic

Answer

Isometric

Answer

Eccentric

Answer

Tetanic

Question 42

What neurotransmitter is released at the neuromuscular junction to initiate muscle contraction?

Accepted Answer

Acetylcholine

Answer

Dopamine

Answer

Serotonin

Answer

Norepinephrine

Question 43

What is the primary role of satellite cells in skeletal muscle?

Accepted Answer

To generate new muscle fibers

Answer

To secrete growth factors

Answer

To store energy

Answer

To transmit nerve impulses

Question 44

Which technique is commonly used to visualize the microscopic structure of skeletal muscle?

Accepted Answer

Histology

Answer

Electromyography

Answer

Magnetic resonance imaging

Answer

Ultrasound

Question 45

The primary function of the sarcolemma is to:

Accepted Answer

Maintain cell integrity and control excitability

Answer

Store calcium ions necessary for contraction

Answer

Generate ATP for muscle contraction

Question 46

The structural unit of skeletal muscle that repeats along its length is called the:

Accepted Answer

Sarcomere

Answer

Myofilament

Answer

Myosin head

Answer

Myofibril

Question 47

Which protein forms the thin filament in the sarcomere?

Accepted Answer

Actin

Answer

Tropomyosin

Answer

Titin

Answer

Myosin

Question 48

The motor end plate, where the muscle cell communicates with the neuron, is located at the:

Accepted Answer

Neuromuscular junction

Answer

Adjacent to the sarcoplasmic reticulum

Answer

Between the sarcolemma and endomysium

Answer

Within the T-tubules

Question 49

Calcium ions play a crucial role in muscle contraction because they:

Accepted Answer

Bind to troponin and initiate muscle contraction

Answer

Provide energy for muscle contraction

Answer

Stimulate the release of acetylcholine at the neuromuscular junction

Question 50

Muscle fibers characterized by high endurance and slow contraction speed are classified as:

Accepted Answer

Type I (slow-twitch)

Answer

Type IIb (fast-twitch, glycolytic)

Answer

Type IIx (fast-twitch, fatigue-resistant)

Answer

Type IIa (fast-twitch, oxidative-glycolytic)

Question 51

In an isometric muscle contraction, there is:

Accepted Answer

No muscle shortening

Answer

Muscle shortening

Answer

Eccentric contraction

Question 52

A common cause of muscle fatigue is the accumulation of:

Accepted Answer

Lactic acid

Answer

Sufficient glycogen stores

Answer

Increased oxygen availability

Answer

Adequate blood flow

Question 53

The condition characterized by progressive muscle weakness and wasting is called:

Accepted Answer

Muscular dystrophy

Answer

Polymyositis

Answer

Rhabdomyolysis

Answer

Myositis