Physiology: Skeletal Muscle 1 Flashcards
what does striation look like under a microscope
alternating dark and light bands (myosin and actin respectively)
what is the initiation of skeletal muscle contraction
neurogenic
describe which muscle types are striated and voluntary etc
what is the initiation of cardiac muscle contraction
myogenic - pacemaker potential
what type of muscle has neuromuscular junctions
skeletal
where does skeletal muscle get Ca ions
entirely from sarcoplasmic reticulum
what is the transmitter at neuromuscular junction
(between muscles and nerves) ACh
define one motor unit
single alpha motor neurone and all the skeletal muscle fibres it innervates
compare the number of muscle fibres per motor unit in thigh muscles (power>precision) to muscles which serve fine movements
muscles which serve fine movements have fewer muscle fibres to each alpha motor neurone
how are skeletal muscles usually attached to skeleton
tendons
how long do skeletal muscle fibres usually extend
entire length of muscle
what causes Ca to be released from the sarcoplasmic reticulum
released from lateral sacs of sarcoplasmic reticulum when surface action potential spreads down T tubules
what do Ca ions bind to on actin filaments
bind to troponin causing tropomyosin to move aside exposing the myosin binding sites
what part of the sarcoplasmic reticulum is Ca released from
lateral sacs
