Structure & function of skeletal MUSCLES:

Question 1

What are myofibrils made from?

Answer 1

= fused cells that share a nuclei
= and cytoplasm, sarcoplasm
= there is a high number of mitochomdria

Question 2

What are muscle fibres made from?

Answer 2

= millions of myofribrils
= made from:
=myosin
= actin
= forms a sacromere

Question 3

What are myosin?

Answer 3

= thicker

Question 4

What are actin?

Answer 4

= thinner

Question 5

What is the sliding filament theory?

Answer 5

= when an action potential reaches a muscle, stimulates a response
= ca2+ ions enter and cause the protein, tropomyosin, that blocks the binding sites for the myosin head, of the actin, to move and uncover the active sites
= whilst ADP is attached to the myosin head, it can bind to the binding site ofthe actin to form a cross bridge

Question 6

What does the cross bridge do?

Answer 6

= angle created in the cross bridge, creates tension, and as a result the actin filament is pulled and slides along the myosin
= the ADP molecule is released
= a new atp molecule binds to the myosin head and this energy causes the head to change shape slighly, and detaches from actin

Question 7

What is found within the sarcoplasm?

Answer 7

= enzyme ATPase activated by calcium ions, hydrolyses ATP into ADP, onto the myson head, releases enough energy for mysoin head to return to original position
= entire process repeats, whilst calcium ions remain high,

Question 8

What is ATP needed for?

Answer 8

= active muslces means a requires a high concentration of ATP
= when aerobic respiration cannot create enough ATP, to meet the demand, anaerobic respiration
= phosphocreatine, which isstored in muscles, assists by providing, phosphate to regenerate ATP from ADP

Question 9

What is A band?

Answer 9

= total length of myosin, darker, there is also actin

Question 10

What is a H zone? =

Answer 10

= where there is myosin early

Question 11

What is the I band?

Answer 11

= where there is only actin, there is no overlap with myosin

Question 12

What is the m line?

Answer 12

= middle point of the myosin

Question 13

What is the z line?

Answer 13

= determines paremeters of 1 sarcomere- actin filaments

Question 14

What happens to these bands when contraction happens?

Answer 14

= myosin attaches to the actin and slides the actin filaments closer to the middle,
= the actin are closer together, so I band becomes smaller
= H zone decreases,
= A band is constant

Question 15

What are slow ti