Muscle Fibre Surface Striations

Question 1

Name the two bands found in a sarcomere and what they are each composed of

Answer 1

Dark A-bands: overlapping thick and thin filaments

Light I-bands: only thin filaments

Question 2

Where is the H zone, and what is it composed of?

Answer 2

Found in the middle of the A-band. Is slightly lighter and contains only thick filaments

Question 3

What is the Z disc?

Answer 3

Is found in each I-band, perpindicular

Question 4

What does the width of the Z disc tell us?

Answer 4

Whether a myosin fibre is slow or fast. Thick = slow, thin = fast

Question 5

What is the difference between slow and fast myosin filaments?

Answer 5

Slow (type I) - contract slowly but keep going for a long time
Fast (type IIa) - intermediate
Fast (type IIb/IIx)) - contract quickly but rapidly get tired (anaerobic metabolism)

Question 6

What can muscle fibre type classification be based on?

Answer 6

ATPase activity

Question 7

What does an acid pre-incubation do?

Answer 7

Inactivates the ATPase of fast fibres (stains only slow fibres)

Question 8

What does an alkaline pre-incubation do?

Answer 8

Inactivates the ATPase of slow fibres (stains only fast fibres)