Myology

Question 1

What is myology?

Answer 1

The study of muscles, including structure, function, disease and injuries.
It covers the study of muscle fibres, myogenesis, and the connections between different muscle groups.

Question 2

What is a type 1 muscle fibre?

Answer 2

Slow twitch
Maintains posture
Has oxidative fibres
Has a high aerobic capacity

Question 3

What is a type 2 muscle fibre?

Answer 3

Fast twitch
Fatigue easily
Are aerobic and anaerobic

Question 4

What is a motor unit?

Answer 4

A neuron which releases chemicals to excite the muscle

Question 5

What is the structure of a skeletal muscle?

Answer 5

Muscle is attached through bone through tendon
The muscle bundle is covered by endomysium
The fascicle is covered by perimysium
The muscle fasciculi group is covered by epimysium

Question 6

What are the layers of a skeletal muscle?

Answer 6

Myofilament
Myofibrils
Muscle fibres
Fasciculi
Muscle

Question 7

Describe the cross-section of a muscle

Answer 7

There are myofilaments within the myofibril which are thick and thin.

Question 8

What is the sarcomere?

Answer 8

The functional unit of the muscle fibre

Question 9

What is the sarcolemma?

Answer 9

The muscle cell membrane

Question 10

What is the sarcoplasm?

Answer 10

The cytoplasm of the muscle cell

Question 11

What is the sarcoplasmic reticulum?

Answer 11

Surrounds each myofibril

Question 12

What are sarcosomes?

Answer 12

Mitochondria which perform aerobic respiration to produce ATP for muscle contraction

Question 13

What are T-tubules?

Answer 13

Invaginations of the sarcolemma

Question 14

What is a triad?

Answer 14

Made up of the 2 terminal cisternae and the T-tubule

Question 15

What is myonuclei?

Answer 15

The nuclei of the muscle cell

Question 16

Describe the structure of a myofilament

Answer 16

Between the 2 Z-lines is where the sarcomere is located.
The anisotropic band includes both thick and thin filaments.
The isotropic band only includes actin filaments.
The H-zone is the central portion of the A-band where only thick filaments are found.
The M-line is the central portion of the H-zone which only includes thick filaments.

Question 17

What are the contractile proteins?

Answer 17

Actin
Myosin

Question 18

What kind of filament is Actin and Myosin?

Answer 18

Actin is thin.
Myosin is thick.

Question 19

Describe the sliding filament theory

Answer 19

• Nerve impulse arrives
• Ach is released
• Depolarisation occurs
• Ca is released
• Ca binds to troponin, changing its shape
• This moves tropomyosin from the active site of actin
• Myosin attaches to actin forming a cross-bridge
• ADP + P = ATP
• Energy is released enabling myosin to pull actin inwards (power stroke)
• ATP attaches to the myosin head and detaches from actin

Question 20

What is myogenesis?

Answer 20

A process by which the development of muscle occurs.

Question 21

Describe myogenesis

Answer 21

• Mesodermal/mesenchymal cells differentiate to form myoblasts
• Myoblasts form myocytes
• Some myoblasts persist after birth, which are known as satellite cells
• These can be activated by exercise or pathology to provide additional myonuclei for muscle growth and repair

Question 22

What are myocytes?

Answer 22

An elongated, cylindrical, multinucleated cell.

Question 23

What is hypertrophy?

Answer 23

The increase in the size of the muscle fibre

Question 24

What are the effects of aging on muscle?

Answer 24

Loss of muscle mass due to loss of muscle fibres