muscle contraction Flashcards
what 2 factors can be adjusted to change gradation of whole muscle tension
the number of muscle fibres contracting within a muscle
the tension developed by each contracting fibre
what is a motor unit
a motor neuron and the skeletal muscle fibres it innervates
what is asynchronous recruitment
different motor units fire and contract at different times which helps delay and prevent fatigue
what is a twitch
the firing of a single action potential to contract the muscle fibre
what causes tetanus
maximal sustained contraction caused when a muscle fibre is stimulated so rapidly it does not have an opportunity to relax between stimuli
why is twitch summation possible
the duration of an action potential is shorter than a twitch
the 2 types of contraction and their differences
isotonic- tension remains constant as muscle changes length
isometric - length remains constant as tension changes
2 types of isotonic contraction
concentric - muscle shortens as it develops tension
eccentric - muscle lengthens as it develops tension
what is used as an energy store in muscles
creatine is produced in the liver and phosphorylated to give creatine phosphate (CP)
CP can donate phosphate to ADP to make ATP
when does central fatigue occur
when the CNS cannot adequately activate motor neurones to working muscles
what are muscle spindles
specialised muscle fibres that play key role in stretch reflex
