Muscle Structure

Question 1

What is a myofibril?

Answer 1

a structure made of fused cells that share nuclei and sarcoplasm

Question 2

What are the myofibrils made up of?

Answer 2

sarcomeres

Question 3

What are muscle fibres made up of?

Answer 3

many myofibrils that collectively bring about force to cause movement

Question 4

What 2 types of proteins make up sarcomeres?

Answer 4

myosin and actin

Question 5

What is the thick filament made up of?

Answer 5

myosin

Question 6

What is tropomyosin and where is it located?

Answer 6

a protein found wrapped around actin

Question 7

What is the A-band?

Answer 7

the total width of the myosin, bands are dark due to both action and myosin

Question 8

What is the H-zone?

Answer 8

the area made up of ONLY myosin

Question 9

What is the I-band?

Answer 9

where there is actin ONLY

Question 10

What is the M-line?

Answer 10

middle of the myosin

Question 11

What is the Z-line?

Answer 11

the line showing the start/end of the sarcomere

Question 12

What is the general structure of slow-twitch fibres?

Answer 12

• contain large amounts of myoglobin (storage of oxygen)
• a rich blood supply (deliver oxygen and glucose for respiration)
• many mitochondria (to produce ATP in aerobic respiration)

Question 13

What is the general structure of fast-twitch fibres?

Answer 13

• more myosin
• large store of glycogen
• store of phosphocreatine
• large amount of enzymes needed in anaerobic respiration

Question 14

What is myoglobin?

Answer 14

a protein that can store oxygen

Question 15

What are the general properties of slow-twitch fibres?

Answer 15

contract slower and respire aerobically for longer periods, adapted for endurance work

Question 16

What are the general properties of fast-twitch muscle fibres?

Answer 16

contract faster to provide short burst of powerful contraction, adapted for intense exercise