The muscular system Flashcards
What are the main properties of muscles?
Electrical excitability - ability to respond to stimuli from neurotransmitter
Contractile - can shorten in response to an action potential
Extensible - can stretch
Elastic - will return to original shape after contraction
What is the structure of skeletal muscle?
Muscle cell covered by endomysium (delicate connective tissue)
Group of fibres covered by perimysium
Whole muscle covered by epimysium
What are the types of levers?
1st class - fulcrum between load and pull
2nd class - load between fulcrum and pull
3rd class - pull between fulcrum and load
Describe the structure of cardiac muscle fibres
1 nucleus
large mitochondria
sarcolemma with T-tubules
T-tubules transverse fibres, allowing a route for Ca2+
Myofibrils throughout, but more disorganised with sarcomeres as a contractile element
Describe the structure of smooth muscle fibres
Non-striated involuntary muscle
Enables involuntary visceral contraction
No T-Tubules
Loosely organised sarcoplasmic reticulum
Thick and thin filaments pull into a ball when contracted
Describe the sliding filament mechanism
- Detachment - ATP bind to myosin head, myosin detaches from actin
- Hydrolysis - ATP splits into ADP +Pi, causes myosin head to adopt ready position
- Cross-bridge - Ca2+ from impulse reveals binding site, myosin head binds to actin
- Release - Bound ADP +Pi are released, myosin head performed a power stroke back to relaxed state
What is the latent, contraction and relaxation period?
Latent - time between stimulation and contraction (2ms)
Contraction - Crossbridge formation (15ms)
Relaxation - When peak tension is developed and stimuli is removed (25ms)
What are the effects of strength, endurance and prolonged inactivity?
Strength - hypertrophy (more myofilaments in each fibre)
Endurance - Increased blood flow to muscles enabling in to maintain moderate activity for longer
Prolonged inactivity - disure atrophy
