Muscle Contraction

Question 1

What theory explains how muscle contraction

occurs?

Answer 1

sliding filament theory

Question 2

Muscle contraction step 1.

Answer 2

An action potential travels into the muscle fibre via T tubules, causing a release of calcium ions from the sarcoplasmic
reticulum.

Question 3

Muscle contraction step 2.

Answer 3

The calcium ions bind to the tropomyosin molecules
and cause them to move, exposing the myosin binding site on
the actin filament.

Question 4

Muscle contraction step 3.

Answer 4

Myosin attaches to actin forming a actin-myosin cross-bridge

Question 5

Muscle contraction step 4.

Answer 5

ATPases hydrolyse ATP to detach the myosin head, allowing reattachment at a further site

Question 6

Muscle contraction step 5.

Answer 6

This cycle continues, causing sarcomeres to shorten.

Question 7

What happens when the nervous stimulation stops in muscle contraction?

Answer 7

Ca2+ ions are actively
transported back into the sarcoplasmic reticulum using energy from ATP hydrolysis. This allows tropomyosin to block the
actin filament from binding to myosin and muscle contraction
stops.

Question 8

What 2 ways can ATP be generated?

Answer 8

via aerobic or anaerobic respiration

Question 9

How does phosphocreatine generate ATP?

Answer 9

by quickly by adding phosphate to a molecule of ADP released by the contracting muscle