muscle contraction

Question 1

muscles tat work together to move bone

Answer 1

antagonistic pairs
contracting muscle agonist
relaxing muscle antagonist

Question 2

skeletal muscle structure

Answer 2

made up of muscle fibres - large bundles of long cells

cell membrane - sarcolemma

transverse T tubules - sarcomella folds inwards across muscle fibre and stick into sarcoplasm
help spread electrical impulses throughout sarcoplasm (reach all parts of muscle fibre)

sarcoplasmic reticulum - internal membranes which store calcium ions

lots of mitochondria to provide ATP

multinucleate

myofibrils - long cylindrical organelles. highly specialised for contraction.

Question 3

myofibrils

Answer 3

thick myofilaments made of protein myosin
thin myofilaments made of protein actin
made of short units called sarcomeres

Question 4

sliding filament theory

Answer 4

myosin and actin slide over one another to make sarcomere contract
simultaneous contraction of lots of sarcomeres - myofibrils and muscle fibres contract

Question 5

when muscle contracts

Answer 5

A band stays same length (thick mysosin and some actin)
I band shorter (actin only
H zone shorter (myosin only)
sarcomere shorter