Structure of Skeletal Muscle

Q.

During muscular contraction which of the following events occur?

1. ‘H’ zone disappears
2. ‘A’ band widens
3. ‘I’ band reduces in width
4. Myosin hydrolyzes ATP, releasing the ADP and Pi
5. Z-lines attached to actins are pulled inwards

1. (a), (b), (c), (d) only

2. (a), (c), (d), (e) only

3. (b), (c), (d), (e) only

4. (b), (d), (e), (a) only

Q. Gap junctions are characteristically found in

1. multi-unit smooth muscles
2. skeletal muscles
3. striated muscles
4. cardiac muscles

Q.

The correct organisation of skeletal muscle is :

1. fascicles →→ muscle fibres →→ myofilaments →→ sarcomere

2. muscle bundles →→ myofibrils →→ muscle cells →→ sarcomere

3. fascia →→ muscle cells →→ myofibrils →→ sarcomere

4. muscle bundles →→ muscle cells →→ muscle fibres →→ sarcomere

Q. Select true or false
i. Shortening of sarcomere occurs when Z lines attached to actin filaments are pushed outwards.
ii. During contraction, I bands retain their lengths.
iii. During contraction, A bands get reduced in length.

1. I- False, ii- False, iii-False
2. I- True, ii- True, iii-False
3. I- True, ii- False, iii-False
4. I- False, ii- True, iii-True

Q. The functional unit of a muscle fibre is the

1. sarcolemma
2. sarcoplasmic reticulum
3. sarcomere
4. sarcoplasm

Q. Which of the following are parts of a fascicle ?

1. Both a and b
2. Perimysium
3. Epimysium
4. Endomysium

Q. Choose the correct sequence of events for the mechanism of muscle contraction:

I. Increase in $C{a^{2+}}^{}$ level leads to the binding of calcium with a subunit of troponin on actin filaments which results in the removal of masking of active sites for myosin.

II. The Z line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere. i.e., contraction.

III. Neural signal reaching the motor end-plate releases acetylcholine resulting in generation of action potential in sarcolemma.

IV. The attached actin filaments are pulled towards the centre of A band

1. III, II, IV, I
2. II, III, I, IV
3. III, I, IV, II
4. II, I, III, IV

Q.

Each muscle fiber is directly surrounded by connective tissue called the

1. perimysium

2. fascia

3. endomysium

4. epimysium

Q. What triggers the release of calcium ions from the sarcoplasmic reticulum?

1. Formation of actin-myosin cross-bridges
2. An action potential
3. An increase in calcium ion concentration
4. Sarcomere contraction

Q.

The cytoplasm within the muscle fiber is known as the

1. sarcoplasm

2. sarcoplasmic reticulum

3. myoglobin component

4. sarcolemma

Q. The muscle bundle is bound by a common collagenous tissue called

1. epimysium
2. fascia
3. fascicle
4. perimysium

Q.

___________a bundle of skeletal muscle fibers surrounded by perimysium

1. myotendrils

2. endomysium

3. myosin

4. fascicles

Q.

Which is the correct arrangement of muscle structures from biggest to smallest?

1. Myofibril, myofilament, muscle fascicle

2. Muscle , fascicle, myofibril, myofilament

3. Myofilament, myofibril , fascicle, muscle

4. Fascicle, myofibril, muscle , myofilament

Q. The functional unit of a muscle fibre is the

1. sarcolemma
2. sarcoplasmic reticulum
3. sarcomere
4. sarcoplasm

Q. Which of the following is not a part of a muscle fibre ?

1. Sarcoplasm
2. Sarcoplasmic reticulum
3. Sarcolemma
4. Fascicle

Q. Which of the following statements are true about fascicles?
I. They are held together by fascia
II. It contains a number of muscle fibres
III. Sarcolemma is the store house of calcium ions
IV. Sarcoplasm contains myofibrils

1. II, IV
2. I, III, IV
3. I, II, IV
4. I, IV

Q. Epimysium is the sheath that covers the

1. muscle
2. none of the above
3. muscle fibre
4. fascicle

Q. Match the following
$\begin{array}{cc}\text{A. Muscle covering}& \text{1. Endomysium}\\ \text{B. Muscle fibre bundle}& \text{2. Epimysium}\\ \text{C. Muscle bundle covering}& \text{3. Fascicle}\\ \text{D. Muscle fibre covering}& \text{4. perimysium}\end{array}$

1. A-1; B-2; C-3; D-4
2. A-2; B-3; C-4; D-1
3. A-3; B-4; C-1; D-2
4. A-4; B-1; C-2; D-3

Q. Which muscle tissue is multinucleate, voluntary, and bears striations?

1. smooth muscle
2. multiunit smooth muscle
3. skeletal muscle
4. cardiac muscle

Q. How is the structure of a sarcomere suitable for the contact ability of the muscle. explain its function according to the sliding filament theory??

Q. The strongest muscle in the human is

1. Biceps
2. Gluteus maximus
3. Stapedius
4. Masseter

Q. Match the following
$\begin{array}{cc}\text{A. Muscle covering}& \text{1. Endomysium}\\ \text{B. Muscle fibre bundle}& \text{2. Epimysium}\\ \text{C. Muscle bundle covering}& \text{3. Fascicle}\\ \text{D. Muscle fibre covering}& \text{4. perimysium}\end{array}$

1. A-1; B-2; C-3; D-4
2. A-2; B-3; C-4; D-1
3. A-3; B-4; C-1; D-2
4. A-4; B-1; C-2; D-3

Q.

Which of the following is true regarding the structure of a skeletal muscle?

1. The ligaments connect the muscle to the skeleton.

2. The endomysium binds the various fasciculi.

3. The I band contains only thin filaments.

4. The sarcoplasmic reticulum is continuous with the plasma membrane and forms transverse tubules.

Q. Muscle fibres are lined by

1. sarcolemma
2. endomysium
3. epimysium
4. both a and b

Q.

During an action potential, calcium is released into the sarcoplasm, near the actin and myosin molecules.Which of the following is the best explanation of what the calcium does?

1. The calcium breaks apart ATP to ADP and P.

2. The calcium binds to the actin and myosin and makes them work together.

3. The calcium removes the tropomyosin block.

4. The calcium causes the release of acetylcholine.

Q.

The muscular tissue which functions throughout the life continuously without fatigue is:

1. Skeletal muscle

2. Cardiac muscle

3. Smooth muscle

4. Voluntary muscle

Q. Muscle tissue is not characterized by its

1. excitability
2. extensibility
3. contractility
4. rigidity

Q.

Which of the following muscle types contains peripherally located, multiple nuclei in its cells?

1. cardiac

2. skeletal

3. smooth

4. all of the above

Q. A muscle bundle is covered by

1. sarcolemma
2. endomysium
3. epimysium
4. perimysium

Q. Active sites are unmasked when calcium binds with a subunit of

1. Troponin
2. Tropomyosin
3. Actin
4. Myosin