Neuromuscular Junction to Myocyte Flashcards Preview

Theme 1 > Neuromuscular Junction to Myocyte > Flashcards

Flashcards in Neuromuscular Junction to Myocyte Deck (32)
Loading flashcards...
1
Q

Neurotransmitter is always ___________ in skeletal muscle contraction

A

Neurotransmitter is always ACETYLCHOLINE in skeletal muscle contraction

2
Q

Acetylcholine after triggering an A.P on Ach receptor on myocyte is eliminated by ______________

A

Acetylcholine after triggering an A.P on Ach receptor on myocyte is eliminated by Acetylcholinesterase

3
Q

What is a sarcolemma

A

The plasma membrane on a muscle fibre

4
Q

Labelling the sacromere

A

Z line at the beginning and end of each sarcomere
H(alf myosin) band
A(ll myosin) band
I(nbetween the sarcomere) band

5
Q

During a contraction. Which of the bands shortens

A band, H band, I band

A

H band and I band

6
Q

What is Myosin

A

Myosin is the ‘‘motor protein’’

Pulls actin

7
Q

1 Myosin has access to ____ Actin

A

1 Myosin has access to 6 Actin

8
Q

1 Actin has access to ___ Myosin

A

1 Actin has access to 3 Myosin

9
Q

During a contraction, Z line of each sarcomere come closer together. True or False

A

True

10
Q

The centre of each Myosin (thick filament) is called the ______

A

Bare zone (only myosin tail, no myosin head)

11
Q

The M line of the Myosin is made up of ________ . The function of the M line is to ____________________________

A

The M line of the Myosin is made up of MINOR PROTEINS . The function of the M line is to KEEP PARALLEL MYOSIN ALIGNED.

12
Q

List 3 components of Actin Filaments

A
  1. Actin
  2. Tropomyosin- block actin-myosin activity
  3. Troponin- controls tropomyosin
13
Q

Actin is made up of G actin monomers that polymerises into double helix strand to form F- actin helix.
F- actin helix has groove on each side that is occupied by tropomyosin. True or False

A

True

14
Q

Troponin attaches to both the actin filament and tropomyosin. True or False

A

True

15
Q

What is Excitation?

A

When a neuron stimulates a muscle cell

16
Q

What is Excitation-Contraction Coupling?

A

the link between depolarisation of the myocytes through a little influx of ca2+ and the consequent huge increase in cytosolic ca2+ that leads to a contraction

17
Q

What is the second messenger in muscle contraction?

A

Free Calcium

18
Q

Where are Ca2+ ions stored in the myocyte

A

Sarcoplasmic Reticulum

19
Q

During Twitch, ca2+ is pumped back into SR,

During Tetany, relaxation is not long enough to pump ca2+ back into SR despite Vm repolarisation. True or False

A

True

20
Q

Tetany lasts for a long period of time. True or False

A

False

21
Q

Twitch is fast, tetany is slow. True or False

A

False. Tetany is fast, Twitch is slow.

Tetany is continuous muscle contraction.

22
Q

What is cross bridge cycling

A

The process of the myosin head pulling the actin, consuming ATP and resetting.
It is controlled by ca2+ ions binding to troponin, which moves tropomyosin away from F- actin groove on actin double helix

23
Q

At rest, ________ blocks the actin-myosin interaction

A

At rest, TROPOMYOSIN blocks actin-myosin interaction

24
Q

Troponin is made up of 3 sub-units. List them and explain their function

A
  1. Troponin I = Inhibitory/binds to actin
  2. Troponin T = Tropo-myosin binding
  3. Troponin C = Calcium ion binding
25
Q

How many Ca2+ binding sites are present on a single Troponin C sub-unit

A

4

26
Q

Beside Ca2+ ion, what other ion is necessary in muscle contraction

A

Magnesium ion , for the production of ATP

27
Q

myosin head cleaves ATP into ADP and P which activates myosin head into high energy state. True or False

A

True

28
Q

Myosin head + ADP binds actin if Ca2+ is absent. True or False

A

False. Only if ca2+ is present

29
Q

Myosin head swivels from 45 degrees to 90 degrees angle. True or False

A

False.

It swivels head from 90 degrees to 45 degrees.

30
Q

Nicotinic receptors and Muscarinic receptors both require agonists. Nicotinic 2nd messenger is an ion channel (Na+/K+) while Muscarinic 2nd messenger is G-protein (which can then act on an ion channel). True or False

A

True

31
Q

List a drug for the following
Nicotinic Agonist
Nicotinic Antagonist
Acetylcholinesterase inhibitor

A
Nicotinic Agonist :
Carbachol - treats glaucoma
Nicotinic Antagonist:
Curare poison
AChE inhibitor
Donepezil for Alzheimer's
32
Q

What is rigor mortis and how does it occur

A

Rigor Mortis is the rigidity of the dead.

It occurs as a result of depleted ATP as respiration stops. Ca2+ is not recycled back into S.R. High cytosolic ca2+ allows cross-bridge cycle contraction. Without ATP, myosin head remain attached to F-actin groove and just stops after power stroke.