skeletal muscle Flashcards
what are the motoneurones of the spinal cord called
alpha-motoneurones
where are the cells bodies of alpha motoneurones found?
ventral horn
what is a motor unit
single alpha motoneurone and all the muscle fibre it innervates
what is focal innervation
each muscle fibre is innervated by one alpha motoneurone
what NT is used at a neuromuscular junction
ACh
what type of receptor does ACh bind to at NMJ
nicotinic
what are end plate potentials
the depolarisation of the muscle membrane at the NMJ
how is smooth contraction achieved
each alpha motoneurone innervates muscle fibres that are spread throughout muscles and they fire asynchronously
how are muscle contractions made to be precise
the innervation ratio is inversely correlated w contractile precision
what is the innervation ratio
number of muscle fibres each alpha neurone activates, low is for more fine control
characteristics of type I muscle fibres
- slow twitch
- low contractile force
- high resistance to fatigue
- energy from oxidative phos
- red
- for posture
characteristics of type II
- fast twitch
- high contractile force
- low resistance to fatigue
- glycolytic source of energy
- white
- for rapid movement
how can we increase force of contaction
- recruit more alpha motoneurones
- increase AP firing rate of each alpha motoneurone -> leads to summation of contractions
what is tetanus
maximum summation, leads to paralysis
what are renshaw cells
inhibitory interneurones, use glycine as NT