Histology-World!

 

 

 

Histology Testbank: Muscle 2a

 

Instructions: For each histology question, pick the one best answer. This histology test bank is also useful for the histology questions on the USMLE (USMLE step 1).

1.
What is the outer connective tissue covering of a muscle?
a. Epimysium
b. Sarcoplasm
c. Perimysium
d. Sarcolemma
e. Endomysium

Answer: a

The outer connective tissue covering of a muscle is the epimysium. Within the muscle, there are subdivisions called fascicles. The perimysium surrounds these muscle fascicles. The endomysium is the covering around an individual muscle fiber. The sarcolemma is the plasma membrane of a muscle cell. The sarcoplasm is the cytoplasm of a muscle cell.

2.
What is myosin?
a. Muscle fibers
b. Myofibrils
c. Myocardium
d. Myofilament
e. Muscle cell

Answer: d

Myofilaments are the contractile protein within a muscle cell. The myofilaments are actin and myosin. The thin filaments are actin and the thick filaments are myosin. The muscle cell is a muscle fiber. The term "muscle cell" and "muscle fiber" are synonymous. A myofibril is a longitudinal bundle of myofilaments within a muscle cell. Myocardium is the muscular layer of the heart. Thus, the myocardium is composed of cardiac muscle.

3.
Where is cardiac muscle found?
a. Myofilaments
b. Myosin
c. Muscle fibers
d. Myofibrils
e. Myocardium

Answer: e

Myofilaments are the contractile protein within a muscle cell. The myofilaments are actin and myosin. The thin filaments are actin and the thick filaments are myosin. The muscle cell is a muscle fiber. The term "muscle cell" and "muscle fiber" are synonymous. A myofibril is a longitudinal bundle of myofilaments within a muscle cell. Myocardium is the muscular layer of the heart. Thus, the myocardium is composed of cardiac muscle.

4.
What type of muscle has visible cross striations?
a. Skeletal muscle
b. Cardiac muscle
c. Smooth muscle
d. Both "a" and "b"
e. "a" "b" and "c"

Answer: d

Both skeletal muscle and cardiac muscle have visible striations. Collectively, skeletal muscle and cardiac muscle are classified as "striated muscle".

5.
What type of muscle is specialized for contraction?
a. Skeletal muscle
b. Cardiac muscle
c. Smooth muscle
d. Both "a" and "b"
e. "a" "b" and "c"

Answer: e

The fundamental property of muscle tissue is that it is specialized for contraction.

6.
What is released at a synapse?
a. Motor unit
b. Motor neuron
c. Motor end plate
d. Neuromuscular spindle
e. Neurotransmitter

Answer: e

A single motor neuron and the aggregation of muscle fibers innervated by that single neuron is called the motor unit. A motor neuron is a neuron which innervates a muscle cell. The point of contact where a neuron contacts a muscle is the motor end plate. A neuromuscular spindle is a receptor which is sensitive to stretching of the muscle. A neurotransmitter is the chemical released by a nerve at a synapse.

7.
Which fiber type is more resistant to fatigue?
a. Red fibers
b. White fibers
c. Intermediate fibers
d. All of the above
e. None of the above

Answer: a

Skeletal muscle fibers can be classified as red fibers, white fibers or intermediate fibers. Red fibers are smaller in diameter; white fibers are larger in diameter. Red fibers have more mitochondria than white fibers. Red fibers make up slow-twitch muscle; white fibers make up fast-twitch muscle. Red fibers are more resistant to fatigue than are white fibers. Red fibers have more myoglobin (oxygen binding pigment) than white fibers. White fibers store glycogen and use anaerobic metabolism.

Red fiber and slow twitch muscle is for endurance.

White fiber and fast twitch muscle is for a burst of power.

8.
Lance Armstrong is the seven time winner of the Tour de France. The Tour de France is a bicycle race which covers between 3500 to 4000 kilometers. What type of muscle fiber probably predominates in his legs?
a. Red fibers
b. White fibers
c. Intermediate fibers
d. All of the above
e. None of the above

Answer: a

Skeletal muscle fibers can be classified as red fibers, white fibers or intermediate fibers. Red fibers are smaller in diameter; white fibers are larger in diameter. Red fibers have more mitochondria than white fibers. Red fibers make up slow-twitch muscle; white fibers make up fast-twitch muscle. Red fibers are more resistant to fatigue than are white fibers. Red fibers have more myoglobin (oxygen binding pigment) than white fibers. White fibers store glycogen and use anaerobic metabolism.

Red fiber and slow twitch muscle is for endurance.

White fiber and fast twitch muscle is for a burst of power.

9.
What region is made of thin filaments?
a. A band
b. I band
c. Z line
d. H band
e. M line

Answer: b

The A band is the darker staining band. The I band is the light band. The I band is made of thin filaments. The Z line runs through the I band. The H band bisects the A band. The M line runs through the H band.

A sarcomere is the segment that runs from Z line to Z line.

10.
On a cross section of a muscle, how many thin filaments surround each thick filament?
a. 2
b. 3
c. 4
d. 6
e. 8

Answer: d

On a cross section of a muscle, each thick filament is surrounded by 6 thin filaments.