Muscle Physiology 1 Flashcards
what are the 5 main functions of skeletal muscle
maintain posture purposeful movement respiratory movements heat production contribution to whole body metabolism
what are the two types of striated muscle
Cardiac
Skeletal
How is skeletal muscle stimulated
Neurogenic stimulation
Where does the calcium that stimulated skeletal muscle contraction come from
the lateral sacs of the sarcoplasmic reticulum
what neurotransmitter is at the neuromuscular junction of skeletal muscle
acetyl choline
what is a skeletal muscle motor unit
a single alpha motor neurone and all the muscle fibres it supplies
muscles that give fine movements (eg. eye movements, intrinsic hand muscles) have more muscle fibres to one alpha motor neurone true/false
false
have less muscle fibres per alpha motor neurone
muscles that give powerful movements have more muscle fibres per alpha neuron true/false
true
what makes up a muscle
muscle fibres arranged in motor units
what are muscle fibres made out of
Myofibrils
-specialised intracellular structures
what are myofibrils made up of
Actin and myosin arranged in sarcomeres
Actin is a thin, light coloured protein true/false
true
Myosin is a thin, dark coloured protein true/false
false
fat, dark coloured protein
what is the definition of a functional unit
the smallest component capable of performing all of the functions
what lines are sarcomeres found between
Z lines
What are the 4 zones of a sarcomere
A band
H-zone
M-line
I band
what is the A band
thick filaments (myosin) with thin filaments overlapping at both ends (actin)
what is the H zone
In the middle of the A band
A lighter area where the thin filaments dont overlap the thick
what is the M line
Extends vertically down the middle of the A band through the H zone
what is the I band
remaining proportions of thin filaments that don’t project into the A band
How is muscle tension produces
the sliding of actin and myosin over each other to shorten the muscle
what are the stages of muscle contraction
- nerve produces an action potential on the surface of the muscle
- action potential spreads down the T tubules triggering release of calcium from the sarcoplasmic reticulum
- calcium binds to troponin which moves troponin out the way exposing the actin binding site
- with the binding of ATP, the myosin cross bridge binds to the binding site on actin triggering the power stroke
what are the stages of muscle relaxation
ATP allows the calcium to be taken up by the sarcoplasmic reticulum and for the cross bridge to be released.
troponin covers up the binding site again.
