structure and regulation of skeletal muscle Flashcards Preview

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Flashcards in structure and regulation of skeletal muscle Deck (19)
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1
Q

what is A band?

A

band that is anisotropic to light

2
Q

what is the I band?

A

band that is isotropic to light

3
Q

what is a sarcomere?

A

minimum functional unit of striated muscle, spans between Z lines

4
Q

where are thick myosin filaments localised to?

A

A band

5
Q

what is the M band?

A

location of attachment between myosin filaments

6
Q

on what does the thickness of the I band depend on?

A

how stretched the muscle is

7
Q

what happens to the thickness of the I band when the muscle is: contracting and stretched?

A

stretched: I band gets wider
contracting: I band gets thinner as it is pulled into the A band

8
Q

what are the components of myofilaments?

A

myosin heavy chain x2
globular heads
a-helical hinge and tail region
regulatory light chain and alkali light chain present on the head of myosin heavy chain

9
Q

what is the role of regulatory light chain?

A

modulates enzyme activity

10
Q

where does calcium bind to the thin filament?

A

tropomyosin/troponin complex

11
Q

what is the role of titin?

A

stabilises myofilament position

12
Q

what does the tension developed by titin depend on?

A

cytoplasmic calcium levels - increased tension in exercise

13
Q

what is the end plate?

A

branching at synaptic terminals

14
Q

what is the NT inside synaptic vesicles at the NMJ?

A

acetylcholine

15
Q

what is the role of the invaginations to the end plate membrane?

A

increase surface area

16
Q

what type of receptors are located in the invaginations inside the end plate membrane?

A

nicotinic acetylcholine receptors

17
Q

what type of receptor is a nicotinic acetylcholine receptor?

A

ligand gated (ionotropic)

18
Q

what are transverse tubules?

A

invaginations of the sarcolemma. role is to carry APs into the depth of the muscle

19
Q

what are end plate projections?

A

protein structures that extend from T tubule to SR membrane