NM - L6 Muscle structure and contraction Flashcards
What surround muscle fibres
a connective tissue layer called the endomysium
what surround fascicles
connective tissue layer called the perimysium
What surrounds the muscle
Fascicles are joined together to from the muscle which surround by a connective tissue sheath - epimysium
what is the sarcolemma
Plasma membrane of the muscle fibre
what is the sarcomere
Unit of a myofibril contained between 2 Z lines
I band is bisected by the Z line
H zone bisects the A band
M line bisects the H zone
What’s does alpha actin do
Maintains the actin lattice
What does dystrophin do
Anchors actin filaments to the sarcolemma
Where are triads located
Junction of the A and I bands so there is 2 triads per sarcomere
What does tropomyosin do
Binds to actin and blocks the myosin binding sites
What does troponin do
Muscle relaxation - binds to actin and tropomyosin to stabilise the interaction
Muscle contraction - binds to calcium displacing tropomyosin and allowing actin and myosin to bind
Is myosin thick or thin
Thick
Sliding filament theory
Muscle shortens by interdigitation of actin and myosin
* The sarcomere shortens
* The I band shortens
* The H zone shortens
* The A band stays constant in length
