Muscle Structure Flashcards
What are skeletal muscles?
Smooth muscle that lines skeletons
And pulls to create movement
Movement can either be…
Reflex
Controlled by conscious thought
Levels of structure of the skeletal muscle
Gross structure (see with eye)
Microscopic structure (cells, requires seeing through microscope)
Ultra structure (proteins that require special techniques to see)
Skeletal Muscle divides into…
Bundle of muscle fibres
A single muscle fibre is..
A muscle cell
Myofibril
Divisions of muscle fibre (muscle cell)
Sarcomere
Repeating unit of the myofibril containing proteins
Proteins in the myofibril
Actin
Myosin
How is a muscle TRIGGERED in the first place to begin contracting?
If the sarcomella (membrane of muscle fibre) is depolarised due to neurotransmitters generating an action potential and sends impulses along muscle fibres
What happens when the sarcomella is depolarised?
Triggers release of Ca2+ ions from sarcoplasmic reticulum ER) of muscle fibre
Which diffuse into myofibril
Released Ca2+ ions can do what?
Trigger the protein called tropomyosin to move away so it unblocks the myosin binding sites on actin
Forming a cross bridge
Myosin heads can now bind to unblocked binding sites on actin
As bonded ATP is hydrolysed to release energy to ADP and Pi
= cross bridge with tension
Formation of a cross bridge and tension means…
Actin can slide along the myosin as the ADP and Pi that had been hydrolysed in formation of the cross bridge is released
How does myosin unbind to actin?
ATP binds to myosin which causes shape in myosin head (change in tertiary structure)
So it will detach from actin
Movement of proteins that causes contraction?
The sliding of actin over myosin together and shortening of sarcomere =contraction of muscles
