Muscle tissue

Question 1

List 4 functions of the muscle tissue

Answer 1

Movement
Maintenance of posture
Joint stabilisation
Heat generation

Question 2

What are smooth muscles composed of?

Answer 2

Grouped, fusiform cells with weak, involuntary contractions.

Question 3

An entire skeletal muscle is enclosed within a dense connective tissue layer called the …………..

Answer 3

Epimysium

Question 4

Each fascicle of muscle fibers is wrapped in another connective tissue layer called the ……………

Answer 4

Perimysium

Question 5

A bundle of muscle fibres is referred to as?

Answer 5

Fascicle

Question 6

Epimysium is continuous with …………..

Answer 6

The tendon binding it to bone

Question 7

Individual muscle fibers (elongated multinuclear cells) is surrounded by a very delicate laver called the ………….

Answer 7

Endomysium

Question 8

Skeletal muscles are capable of undergoing mitosis. True or false?

Answer 8

False

Question 9

The source of regenerating cells of skeletal muscles is the ………………………

Answer 9

Sparse population of mesenchymal satellite cells

Question 10

The sparse population of mesenchymal satellite cells that are associated with skeletal muscle regeneration lies ………….

Answer 10

within the external lamina of each mature muscle fiber

Question 11

A note on satelite cells

Answer 11

Satellite cells are inactive, reserve myoblasts that persist after muscle differentiation. After injury or certain other stimuli, the normally quiescent satellite cells become activated, proliferating and fusing to form new skeletal muscle fibers.

Question 12

What’s the role of satelite cells in muscle growth?

Answer 12

After extensive exercise, they fuse with their parent fibers to increase muscle mass beyond that occurring by cell hypertrophy.

Question 13

The regenerative capacity of skeletal muscle is limited, however, after major muscle trauma or degeneration. True or false

Answer 13

True

Question 14

Cardiac muscles have virtually no regenerative capacity beyond early childhood. This is probably due to ………..

Answer 14

Their lack of satellite cells

Question 15

Defects or damage (eg, infarcts) in heart muscle are generally replaced by ………………

Answer 15

fibroblast proliferation and growth of connective tissue, forming myocardial scars

Question 16

Describe briefly the repair of vascular smooth muscle

Answer 16

After injury, viable smooth muscle cells undergo mitosis and replace the damaged tissue. Contractile pericytes from the walls of small blood vessels participate in the repair of vascular smooth muscle.

Question 17

Classify muscle tissues on the basis of their appearance.

Answer 17

Striated muscle
Smooth muscle

Question 18

Striated muscle tissue is subclassified on the basis of its location thus;

Answer 18

skeletal and cardiac muscle tissue

Question 19

Outline the general features of skeletal muscle tissues

Answer 19

1. It is formed of striated muscle fibers
2. Each muscle fiber contains many nuclei. They are located immediately under the plasma membrane.
3. Each muscle fiber contains parallel myofibrils ( 80% myofibrils in the fibre), which are transversely striated.
4. The cytoplasm of the muscle fiber is known as Sarcoplasm (Greek sarkos - flesch)
5. The sarcoplasm contains glycogen, lipids and myoglobin (pigmental protein; it can take up, store, or give up oxygen as needed).
6. The function of this tissue is controled voluntarily - it could be contracted or relaxe by will - skeletal muscle came to be known also as voluntary muscle.

Question 20

Outline the general features of the skeletal muscle tisssue

Answer 20

1. It is formed of striated muscle fibers .
2. Each muscle fiber contains many nuclei. They are located immediately under the plasma membrane.
3. Each muscle fiber contains parallel myofibrils ( 80% myofibrils in the fibre), which are transversely striated.
4. The cytoplasm of the muscle fiber is known as Sarcoplasm (Greek sarkos - flesch)
5. The sarcoplasm contains glycogen, lipids and myoglobin (pigmental protein; it can take up, store, or give up oxygen as needed).
6. The function of this tissue is controled voluntarily - it could be contracted or relaxe by will - skeletal muscle came to be known also as voluntary muscle.

Question 21

What is a myofibril?

Answer 21

Any of the contractile threads found in striated muscle fibres

Question 22

A brief histology of the cardiac muscle tissue

Answer 22

Consists of branched, striated fibers, with one or two centrally located nuclei and intercalated discs

Question 23

What are the functions of intercalated discs in muscle tissues?

Answer 23

The intercalated discs hold and bind the cardiac muscle cells through fascia adherens and desmosomes.
They also ensure the contractile force is transmitted from one cardiac muscle cell to another.
Intercalated discs mainly ensure that the cardiac muscle functions as a well-coordinated unit.

Question 24

What percentage of the body weight do skeletal muscles make up?

Answer 24

40%

Question 25

General features of skeletal muscles include;

Answer 25

• Fibers are long, cylindrical, multinucleated

• Tend to have smaller diameter in small muscles and larger in large muscles. 1 mm- 4 cm in length

Question 26

What are myoblasts?

Answer 26

They are the embryonic precursors of myocytes converted to muscle fibers as contractile proteins accumulate within their cytoplasm.

Question 27

Striated appearance of skeletal muscle is due to ………

Answer 27

Light and dark banding

Question 28

Enlargement of muscles is an increase in size rather than number, why is that?

Answer 28

Number of muscle fibers remain constant after birth, hence, enlargement of muscles is an increase in size rather than number.

Question 29

Brief histology of smooth muscle tissue;

Answer 29

Spindle-shaped, nonstriated fibers with one centrally located nucleus.

Question 30

What is the distribution of smooth muscle tissue?

Answer 30

• Walls of hollow internal structures such as blood vessels
• Airways to lungs
• Stomach
• Intestines
• Uterus.

Question 31

Name the types of muscle tissue in order of increasing contraction speed.

Answer 31

Smooth muscle tissue - slowest
Cardiac muscle - moderate
Skeletal - fastest

Question 32

Which muscle tissues have involuntary and autorythymic nervous control?

Answer 32

Smooth muscle tissues and cardiac muscle tissues.