Flashcards in Muscle 1 Deck (29)
What are the 3 types of muscle?
skeletal, smooth and cardiac
Give 2 examples of skeletal muscle.
voluntary muscles, diaphragm
Give 2 examples of where you would find smooth muscle.
blood vessels, airways
What is a skeletal muscle cell?
a muscle fibre
What are skeletal muscle cells formed from in utero? Comment on the nuclei.
formed from mononucleate myoblasts
What is the repair system of muscle like?
poor. Myoblasts do not replace cells if damaged
How can muscle try to repair itself? 2 ways
- cells replaced after injury by satellite cells which differentiate to form new muscle fibres
- other fibres undergo hypertrophy to compensate
What are striations in skeletal muscle?
repeating units of structures on muscle fibre myofibrils called sarcomeres
What are myofibrils?
clusters of units of many repeating units of sarcomeres inside a muscle cell (fibre)
What are myofibrils made up of? (i.e. sarcomeres)
myofilaments such as actin and myosin and titin
What is the 'thick filament'?
What is the 'thin' filament?
How does the interaction of actin and myosin lead to contraction?
- myosin has lots of 'heads' that are capable of binding to sites on actin to form cross bridges
- myosin binds to actin, pulling on the actin filament, shortening the sarcomere
-ATP binds which causes the myosin head to release the actin
-when the ATP is broken down to ADP and Pi again, the myosin head cocks back into the optimum position to bind to actin again
What do troponin and tropomyosin do?
-tropomyosin partially covers the myosin binding site on the actin
-troponin holds the tropomyosin in the blocking position
How does the interaction of calcium help contraction?
it binds to the troponin causing it to change shape and move the tropomyosin out of the way so that myosin can bind to actin
Where is the calcium stored in the muscle fibre?
in the sarcoplasmic reticulum
What is the name given to the plasma membrane of a muscle fibre?
What is a T -tubule?
a deep invagination of the sarcolemma
What do T-tubules do?
allow depolarisation of the sarcolemma to quickly reach the inside of the muscle cell to allow for voltage gated control of the calcium channels to mediate contraction
What is a motor unit?
a motor neurone and the muscle fibres it innervates
What is tension?
force exerted BY muscle
What is load?
force exerted ON muscle
What is isometric contraction?
contraction with constant length e.g weightlifting
What is isotonic contraction?
contraction with shortening length e.g running
What is lengthening contraction?
contaraction with increasing length e.g sitting down
What is a twitch?
When a muscle fibre is stimulated by a single Action potential to cause a brief contraction
What does contraction time depend on?
What is latent period when referring to contraction?
time before excitation contraction starts