muscle structure, action and function Flashcards
muslcle structures
Muscle
Fascicles
Muscle fiber (Muscle cell)
Myofibrils
Sarcomere
connective tissue around muscle
Epimysium
Connective tissue covering the entire muscle
Perimysium
Connective tissue surrounding the bundles of muscle fibres
Endomysium
Surrounds individual muscle fibres
muscle action
Myosin
A- band
Actin
Z line to A band
Z disc
Transverse structure
Anchors thin and thick filaments to elastic filament
M line
Transverse structure
Means middle disc
Centre of sarcomere with links mysoisn
sacromere -actin and myosin
Actin
Thin, light and twisty
Myosin
Thick and lumpy
Z line
Separates each sarcomere
Muscle contraction
Actin and myosin sliding to bring the Z lines closer together
SLIDING FILAMENT MODEL OF MUSCLE CONTRACTION
At rest actin and myosin don’t touch, but they want to
muscle contraction
Actin and myosin blocked
“protein bodyguards”
Troponin
Tropomyosin
Need to be “bought off” by
ATP (molecular currency)
Calcium
Muscle cells have nuclei and mitrochondria (produced the ATP)
Sarcoplasmic reticulum (transport and storage system)
Walls full of calcium pumps
Uses ATP to store up calcium ions
Calcium channels(voltage gated)
Regulates calcium needed to initiate muscle contracture and reabsorbs it to allow muscle to relax
muscle contractions steps
Action potential – neuromuscular junction
Travels along muscle cell membrane – sarcolemma
T tubule opens calcium channels in the sarcoplasmic reticulum
Calcium binds to troponin and this pulls the tropomycin away from actin binding sites
Actin and myosin can finally bind!
Myosin that has converted ATP (ADP plus phosphate) can then change shape and in doing so pulls the actin over it causing the muscle to contract
Myosin then released the ADP, changes shape, a new ATP binds to it and it releases from the actin
It then processes the new ATP to start again
Calcium pumps restock the Calcium in SR, grab Ca floating around, unbinds from the troponin and they change shape and the bodyguards go back into place
function of muscle
Locomotion
Keeping us upright
Being able to balance of 2 legs
Support the abdominal cavity and our organs
Control vales and body openings
Produce heat
