L7 Muscle Flashcards
Skeletal muscle
1.Attach to bone
2. Add shape to muscle
3. Voluntary contractions relaxation
4. 拉絲
Cardiac muscle
Involuntary
Quick and sharp movement
Do not fatigue
拉絲
Smooth muscle
Involved in substance movement
唔拉絲
Involuntary
Usually do not fatigue
Structure of muscle
Muscle fibre-) endomysium
Fasicle-) perimysiu
Muscle -) epimysium
Sarcomere-) myofilament -) muscle fibre -) fasicle -) muscle
Sarcomere shorten = muscle contraction
Myofibrils
Bundle of thick + thin filaments
Sarcomere is smallest
Z disc is around sarcomere
Myofilament (mad eof myofibrils)
Composed of actin, troponin, tropomyosin
Actin: binding site of myosin
Tropomyosin: cover the binding site of actin when at rest
Troponin: control tropomyosin
Neuromuscular junction step of contraction
- Action potential of synaptic bulb received
- Acetylcholine released to the synaptic cleft
- Acetylcholine bind to nicotine cholinergic receptor on motor end plate
- Sodium enter the cell and depolarise
- Action potential generated triggered ca2 release
- Ca2 release will stimulate muscle contraction
Cross bridge cycle
- Arrival of action potential
- Ca2 ctivated troponin
- Exposure of myosin-binding site on actin
- Form cross bridge by binding myosin head & actin
Muscle energy source from…
Mitochondria
Creatine
2 types of muscle fibre
Slow twitch fibre (red)
With many mitochondria
Optimized for aerobic movement / endurance
Fast twitch fibre
Contain less mitochondria
For strength- contract rapidly but fatigue easily
Larger and stronger
Factors: force of muscle contraction
Number of cross bridge form
Number of myosin head reach the filament
Number of binding site on thin filament
Contraction: isotonic vs isometric
Isotonic: concentric & eccentric
Muscle length differ
Isometric: muscle tense, length no change, no slide.
Muscle action
Agonist (quad)
Antagonist (hamstring)
Synergist (assist agonist / prime mover)
