Muscles

Question 1

What is the sliding filament model?

Answer 1

• Action potential travels down t-tubules to sarcoplasmic reticulum.
• Ca2+ released, which binds to tropomyosin, moving troponin out of the way.
• Actin-myosin bridge forms.
• ATP binds, causing it to detach. Converted to ADP and Pi.
• Moves filament to the left. (Conformational change)

Question 2

What is creatine phosphate?

Answer 2

• Creatine phosphate acts as a reserve supply of phasphate, allowing ADP to be convertedback into ATP.

Question 3

what are T-tubules?

Answer 3

• folds of the sarcolemma which spread electrical impulses throughout the sarcoplasm, into the sarcoplasmic reticulum specifically.

Question 4

What are Light/I bands?

Answer 4

only actin

Question 5

What are dark/A bands?

Answer 5

dark due to presence of myosin
- darker edges are where A&M overlap

Question 6

What are H bands?

Answer 6

• only myosin (WITHIN A BAND)

Question 7

what is an M-line?

Answer 7

• attachment for myosin filaments

Question 8

What is a z-line

Answer 8

attachment site for actin

Question 9

what is a sarcomere

Answer 9

section of a myofibril between 2 z-lines

Question 10

What happens when the T-tubules conduct the depolarisation to the sarcoplasmic reticulum?

Answer 10

Opens Ca2+ ion channels, allowing Ca2+ ions which have been actively absorbed from the sarcoplasm to diffuse out.

Question 11

What happens to Ca2+ ions when they diffuse out of the sarcoplasmic reticulum?

Answer 11

Bind to troponin and cause it to change shape, which pulls tropomyosin out of the way and allows actin and myosin to form a cross-bridge.