Muscle 2

Question 1

Label H zone, I band, A band and M line?

Answer 1

H band – between small filaments
A band – length of thick filament, overlap thick and thin
I band – gap between thick filaments
At full contraction H and I bands disappear, A band never changes

Question 2

Answer 2

Question 3

At full contraction what bands dissappear?

Answer 3

H and I
A remains

Question 4

How does contraction occur?

Answer 4

Neuromuscular junction
1) AP propagates to neuromuscular junction
2) Depolarisation cause influx Ca2+ ions
3) Ca2+ cause vesicle release ACh
4) ACh receptors on sacolenna
5) Influx Na+ cause depolarisation
6) Ion shift down T tubules
7) Ca2+ enter myocyte
8) Influx calcium through Ryanodine receptors on sarco ret
9) Ca2+ binding to troponin- conformational change
Expose myosin binding sites on actin
10) Contraction occurs in presence ATP
11) Remove Ca2+- muscle relax

Question 5

How does contraction occur?

Answer 5

1) Action potential travels through motor neuron
2) At neuromuscular junction ACh released
3) ACh bind muscle receptor
4) Depolarisation cause influx Na+
5) Influx sodium triggers AP propgates along cell
6) AP into T-tubules cause Ltype calcium channels open, release stored Ca2+
7) Release Ca2+ causes ryanodine receptors releease calcium
8) Contraction stimulated
9) Calcium pumped back
10) Relaxes muscle

Question 6

What is junction called between motor and muscle cell?

Answer 6

Neuromuscular junction

Question 7

What is region between two Z lines called?

Answer 7

Sarcomere

Question 8

Explain sliding filament theory?

Answer 8

1) Rest
2) SR releases calcium
3) Calcium binds troponin- cause tropomyosin shift
4) Allows myosin crossbridge to attach to actin
5) ATP undergoes hydrolysis become ADP
6) Myosin head changes shape and pulls actin (power stroke)- cause muscle fibres shorten
7) Calcium returns SR

Question 9

Function golgi tendon organs?

Answer 9

Change tension

Question 10

Function muscle spindles?

Answer 10

Provide length muscle length and rate change

Question 11

Draw a graph showing depolarisation?

Answer 11

Question 12

What removes ACh and stops contraction?

Answer 12

Acetylcholinesterase

Question 13

Function acetylcholinesterase?

Answer 13

Remove ACh- stop contraction

Question 14

What 2 things remove calcium?

Answer 14

SERCA on SR
Ca2+ ATPase on membrane

Question 15

Define motor unit?

Answer 15

The neuron and its associated fibres that it innervates

Question 16

More precise have smaller or larger motor units?

Answer 16

More precise- smaller
Less precise- large

Question 17

What channels allow Ca2+ in to cause contraction?

Answer 17

L type

Question 18

What receptors responsible for release of stored Ca2+?

Answer 18

Ryanodine

Question 19

What makes up nucleotide?

Answer 19

Pyrimidine/purine
Sugar group
Phosphate group

Question 20

Name 3 pyrimidines?
Name 2 purines

Answer 20

Pyrimidines
Cytosine
Thymine
Uracil

Purines
Adenine
Guanine

Question 21

What are 2 sugar groups- how appear?

Answer 21

RNA- ribose
DNA- deoxyribose

Question 22

State 3 foods high in purines?

Answer 22

Meat
Offal
Seafood and fish

Question 23

What is a disease caused by excess uric acid?

Answer 23

Gout

Question 24

What is gout caused by?

Answer 24

Excess uric acid

Question 25

How are nucleotides (purines) broken down?

Answer 25

1) Body nucleotides
2) Purines
3) Uric acid
4) Excreted urine

Question 26

How is uric acid excreted?

Answer 26

1) Breakdown gut
2) Renal excretion

Question 27

What are pyrimidines broken into?

Answer 27

CO2 and NH3