Muscles

Question 1

3 types of muscles

Answer 1

cardiac
Smooth
Skeletal

Question 2

What is skeletal muscle

Answer 2

Is attached to the bone via tendon
Incomprensible
Muscles work in pairs-agonist and antagonists

Question 3

What happens when muscles contract

Answer 3

I band is smaller
H-zone is smaller
Z - lines closer together(sarcomere is smaller)
A-band remains the same

Question 4

What is myosin

Answer 4

Has a globular head , hinged so it can be more back and forth

Question 5

Muscle contraction mechanism
First stage

Answer 5

After AP is triggered muscle cell , Ca2+ ions released from sarcoplasmic reticulum into sarcoplasm

Question 6

Stage 2 muscle contraction

Answer 6

Ca2+ binds to the tropomyosin and causes the protein to change shape which pulls out of the binding site

Question 7

Stage 3 muscle contraction

Answer 7

Myosin head can now bind to binding site and forms cross bridges

Question 8

Stage 4 muscle contraction

Answer 8

Myosin head performs the power stroke

Question 9

Stage 5 muscle contraction

Answer 9

ATP now binds to myosin head hydrolysed by ATP and release energy to break cross bridges myosin head is released and repositioned to attach to another actin binding site

Question 10

Stage 6 muscle contraction

Answer 10

Cycle repeats as long as there is enough ATP in sarcoplasm but if the muscle stops receiving AP calcium ions detach

Question 11

What does sarcoplasmic reticulum contain ?

Answer 11

Contains calcium ions
Has bundle of fibres
Muscle cells contain fibres
Myofibril