what cells to skeletal muscles have?
what is skeletal muscles formed from?
skeletal muscle fibres
what does stimulation of muscle fibre in the skeletal muscle do?
excitation the entire cell
where do motor neurones form synapses?
on the skeletal muscle fibres at the motor endplates
what are slow muscle fibres?
postural muscles, mainly type 1 fibres
what are fast muscle fibres?
mainly type 2 fibres, better suited to generate large forces but can fatigue rapidly
how do you see the different types of fibres?
what are isotonic contractions?
when muscle shortens on contraction against a constant load e.g. flexing a limb
what are isometric contractions?
muscle constrained to a constant length e.g. holding heavy object still
How does muscle fibre contraction happen ?
- Nerve AP
- Nerve ending secretes ACh
- End plate potential
- muscle action potential
- T tubules depolarise
- opens Ca2+ channels of sarcoplasmic reticulum
- sarcoplasm Ca2+ increases
- muscle fibre contracts
- Ca2+ goes back
- muscle fibre relaxes
what happens in Excitation-contraction coupling?
AP from motor endplate, goes to T tubules, leading to SR, AP stimulates ion channels, releasing calcium, into the cytosol, myosin binds to actin( protein in thick filament). Contraction continues if Ca high and ATP present.