Skeletal Muscles (errors)

Why do we need a stats tests / standard deviations / error bars?

to see if difference is significant

why does converting pyruvate to lactate allow the continued production of ATP by anaerobic respiration

• reduction oxidises NADH to NAD

• to reduce troise phosphate to pyruvate again

• so glycolysis can continue

If theres more dehydrogenase activity, that is used in krebs cycke, in the muscle,,

• there is an increase in aerobic respiration, as krebs cycle only occurs in aerobic respiration

how does higher dehydrogenase activity, occuring in the krebs cycle, make you be able to exercise for a longer period of time

• more aerobic respiration produces more ATP

• you can aerobically respire for longer

• less lactate is built up

order of specifcation for:

• sacromere

• muscle filament

• myofibril

• muscle fibre

muscle fiber > myofibril > sarcomere > muscle filament

Hows does a decrease in pH reduce the ability of calcium ions to stimulate muscle contraction (5)

1. pH lowering changes the tertiary shape / structure of the Ca2+ binding sites on troponin

2. Ca2+ is no longer complimentary to binding sites so fewer binding sites are binded to

3. tropomyosin moves awsay less

4. fewer binding sites on actin revealed

5. fewer cross bridges form

Draw the structue of a myofibril

Describe initiation of muscle contraction (5)

1. Motor neurone releaes Ach

2. Ach attaches to sacrolemma receptors, depolarising sarcolemma

3. if threshold is reached, action potential spreads along entire muscle fibre

4. depolarisation spreads down T tubules

5. causing sacroplasmic reticulum release of Ca2+

Explain the role of Ca2+ in muscle contraction (4)

1. ca2+ binds to troponin

2. tropomyosin changes shape

3. exposing binding site for myosin head

4. to form actino-myosin crossbridges

Explain why atheletes take creatine supplements (3)

1. ATP combines with C to form ADP and PC (phosphocreatine) at rest

2. during exercise, ATP is quickly regenerated with PC and ADP

Explain carbohydrate loading

1. eating more carbohydrates a few days before competition

2. maximises glycogen storage in muscle

3. during events, glycogen is hydrolysed to glucose to be used in aerobic respiration

An increase in muscle activity causes increase in heart rate. describe and explain how (4)

1. increase in CO2 concentration of blood is detected by chemoreceptors

2. sends more impulses to medulla / cardiac center

3. increased frequency of nervous impulses along sympathetic pathway

4. to SAN

describe the events leading up to ca 2+ leaving the sarcoplasmic reticulum (6)

1. motor neurone stimulated, releasing Ach

2. Ach diffuses down neuromuscular junction

3. Ach binds to complimentart sarcolemma receptors, depolarising sarcolemma

4. if threshold is reachemd action potential spreads along enire muscle fibre

5. depolarisation spreads down T tubules

6. reaching sarcoplasmic reticulum