Ch15 Muscles

Question 1

Muscle contraction

Answer 1

1. Ca ions channels open
2. calcium ions diffuse into myofibrils from sarcoplasmic reticulum
3. Ca ions bind to tropmomyosin
4. uncover binding site of actin
5. myosin heads attach to actin filaments
6. ADP molecule released and sliding of actin and myosin filaments
7. ATP binds to myosin head
8. myosin head bends
9. ATPase hydrolyses ATP
10. muslin head goes back to original position

Question 2

Large glycogen concentration

Answer 2

1. Source of glucose- energy store
2. for respiration to provide ATP

Question 3

Evidence for sliding filament mechanism

Answer 3

1. I band becomes narrower
2. Z lines move closer
3. H zone becomes narrower

Question 4

Phosphocreatine

Answer 4

1. released Pi to bond with ADP
   2.allows regeneration of ATP without respiration

Question 5

Advantage of capillaries

Answer 5

1. short diffusion pathway
2. provides oxygen and glucose for respiration
3. removes CO2/heat

Question 6

Fast twitch fibre

Answer 6

1. immediate fast contraction
2. explosive
3. energy is anaerobically generated
4. high glycogen concentration
5. stores phosphocreatine

Question 7

slow twitch fibre

Answer 7

1. sustained contraction
2. aerobic energy generation
3. maintaining endurance
4. many mitochondria for ATP
5. prevent lactic acid build up

Question 8

Neuromuscular junction

Answer 8

1. Nerve impulse depolarises presynaptic membrane
2. calcium channels open
3. calcium ions enter presynaptic membrane
4. synaptic vesicles fuse with presynaptic membrane
5. acetlycholine is released
6. diffuses across cleft
7. attaches to receptor on post synaptic membrane
8. sodium channels opened
9. sodium ion enter
10. causing depolarisation of sarcolemma

Question 9

Differences between neuromuscular and cholinergenic synapse

Answer 9

1. neurone to neurone vs neurone to muscle
2. action potential in neurone and no action potential in sarcolemma
3. no summation in muscle
4. muscle response always excitory
5. some neuromuscular junctions have different neurotransmitters

Question 10

Muscle feature

Answer 10

1. multi-nucleate
2. contain myoglobin
3. sarcomere
4. lots of mitochondria
5. actin and myosin filaments