Muscle 2 Flashcards
Label H zone, I band, A band and M line?
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
At full contraction what bands dissappear?
H and I
A remains
How does contraction occur?
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
How does contraction occur?
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
What is junction called between motor and muscle cell?
Neuromuscular junction
What is region between two Z lines called?
Sarcomere
Explain sliding filament theory?
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
Function golgi tendon organs?
Change tension
Function muscle spindles?
Provide length muscle length and rate change
Draw a graph showing depolarisation?
What removes ACh and stops contraction?
Acetylcholinesterase
Function acetylcholinesterase?
Remove ACh- stop contraction
What 2 things remove calcium?
SERCA on SR
Ca2+ ATPase on membrane
Define motor unit?
The neuron and its associated fibres that it innervates
More precise have smaller or larger motor units?
More precise- smaller
Less precise- large
What channels allow Ca2+ in to cause contraction?
L type
What receptors responsible for release of stored Ca2+?
Ryanodine
What makes up nucleotide?
Pyrimidine/purine
Sugar group
Phosphate group
Name 3 pyrimidines?
Name 2 purines
Pyrimidines
Cytosine
Thymine
Uracil
Purines
Adenine
Guanine
What are 2 sugar groups- how appear?
RNA- ribose
DNA- deoxyribose
State 3 foods high in purines?
Meat
Offal
Seafood and fish
What is a disease caused by excess uric acid?
Gout
What is gout caused by?
Excess uric acid
