muscles

Question 1

describe a sarcomere

Answer 1

distance between z lines
gets shorter during muscle contraction
I bands are the light region of just actin gets shorter during muscle contraction
A bands dark where myosin and action over lap and stays the same length
H zone in the middle of the A band

Question 2

describe the role of ATP

Answer 2

hydrolysis of ATP provides energy used in muscle contraction to break cross bridges and detach myosin heads. allows myosin heads to move back to their original position

Question 3

what are the stages in muscle contraction

Answer 3

action potential arrives in muscle cell membrane
and is carried across the sarcoplasm in T tubules
causes sarcoplasmic reticulum to release Ca2+ into myofibrils which bind to troponin
causes tropomyosin to be displaced and reveals myosin binding sites on actin
allows myosin heads to attach to actin binding sites and form cross bridges
myosin head changes angle and release ADP
causes actin filament to slide relative to myosin
ATP used to detach myosin from actin
ATPase breaks ATP into ADP

Question 4

what is the role of calcium ions in muscle contraction

Answer 4

binds to troponin 
causing tropomyosin to be displaced 
reveals myosin binding sites on actin 
allowing myosin actin cross bridges to form
Activates ATPase on myosin

Question 5

what can affect the action of calcium ions

Answer 5

pH temp can change the shape of the calcium receptors

Question 6

what is the role of tropomyosin

Answer 6

blocks myosin binding site on actin

moves from binding site due to CA2+ allowing cross bridges to form

Question 7

describe the sliding filament theory

Answer 7

when contracted actin and myosin overlap more

actin moves along the myosin so actin pulls z lines closer together

Question 8

describe fast twitch muscles

Answer 8

used for explosive movement
have enzymes for anaerobic respiration, phosphocreatine for ATP regeneration and a higher quantity of myosin for powerful contractions

Question 9

describe slow twitch muscles

Answer 9

used for endurance
lots of mitochondria for aerobic resp
good supply of glycogen
rich capillary network to provide oxygen

Question 10

why do muscle cells contain glycogen

Answer 10

contains glycogen granules as a store of glucose for use in respiration