Myology Flashcards
What is myology?
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.
What is a type 1 muscle fibre?
Slow twitch
Maintains posture
Has oxidative fibres
Has a high aerobic capacity
What is a type 2 muscle fibre?
Fast twitch
Fatigue easily
Are aerobic and anaerobic
What is a motor unit?
A neuron which releases chemicals to excite the muscle
What is the structure of a skeletal muscle?
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
What are the layers of a skeletal muscle?
Myofilament
Myofibrils
Muscle fibres
Fasciculi
Muscle
Describe the cross-section of a muscle
There are myofilaments within the myofibril which are thick and thin.
What is the sarcomere?
The functional unit of the muscle fibre
What is the sarcolemma?
The muscle cell membrane
What is the sarcoplasm?
The cytoplasm of the muscle cell
What is the sarcoplasmic reticulum?
Surrounds each myofibril
What are sarcosomes?
Mitochondria which perform aerobic respiration to produce ATP for muscle contraction
What are T-tubules?
Invaginations of the sarcolemma
What is a triad?
Made up of the 2 terminal cisternae and the T-tubule
What is myonuclei?
The nuclei of the muscle cell
Describe the structure of a myofilament
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.
What are the contractile proteins?
Actin
Myosin
What kind of filament is Actin and Myosin?
Actin is thin.
Myosin is thick.
Describe the sliding filament theory
- 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
What is myogenesis?
A process by which the development of muscle occurs.
Describe myogenesis
- 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
What are myocytes?
An elongated, cylindrical, multinucleated cell.
What is hypertrophy?
The increase in the size of the muscle fibre
What are the effects of aging on muscle?
Loss of muscle mass due to loss of muscle fibres
