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PMP-101 > 1. Muscular contractions - NS > Flashcards

1. Muscular contractions - NS Flashcards

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1
Q

CNS (recap)

A
  • Brain
    -Spinal chord
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2
Q

PNS recap

A
  • all of the other nerves
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3
Q

Different types of PNS

A
  1. Sensory division (afferent)
  2. Motor division (efferent) > Somatic nervous system
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4
Q

What is the somatic Nervous system?

A
  1. Part of the peripheral nervous system
  2. Controls movement of skeletal muscles
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5
Q

Where is the CORTEX in the brain?

A

Cerebral Cortex is the outer layer that lies on top of your cerebrum

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6
Q

What is the role of the CORTEX?

A

Key role in memory, thinking, learning, reasoning, problem-solving, emotions, consciousness and functions related to your senses

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7
Q

Different types of homoluculs

A

a) Motor
b) Sensory

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8
Q

Tracts

A

Ascending + Descending

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9
Q

Ascending tracts

A

relay information from the spinal cord to the sensory cortex

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10
Q

Descending tracts

A

relay information from the motor cortex to the spinal cord

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11
Q

Sensory neurones

A

Sense touch, stretch, pain etc.

Relay information to spinal cord and brain

Enter spine at the dorsal horn, via dorsal root

Unipolar neurones – cell body is at dorsal root ganglion

Myelinated

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12
Q

Myelinated, what is the advantage?

A

Neurone is isolated - allows more rapid transmission of neural information along neural fibres

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13
Q

Motor Neurones

A

Relay nerve impulses from the spine to trigger contraction of skeletal muscle
>Exit spine via ventral root

ONE Alpha motor neurone

Multipolar and myelinated

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14
Q

ONE Alpha motor neurone

A

Long

ONLY 1 neurones extends from spinal chord and the muscle (different in automatic NS)

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15
Q

What the junction called when the neurone and muscle interact / join?

A

Neuromuscular junction

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16
Q

How do neurones and muscle interact?

A

The neurone connects to 1 muscle fibre - NEUROMUSCULAR JUNCTION and communicates

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17
Q

Which neurotransmitter is released at the junction??

A

Acetylcholine is the neurotransmitter at skeletal muscle NMJs

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18
Q

What type of receptor is Nicotinic Acetylcholine?

A

Ligangated ion channel

(in the plasma membranes of certain neurons and on the postsynaptic side of the neuromuscular junction)

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19
Q

What does the Acetylcholine bind to?

A

Binds to and activates Nicotinic Acetylcholine Receptor
> Ionotropic

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20
Q

Post synaptic membrane

A

Motor End Plate (MEP)

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21
Q

At post synaptic membrane if signal is big enough…

A

trigger effect in muscle (ACTION)

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22
Q

Types of muscle:

A
  1. Skeletal (striated)
  2. Cardiac (straited)
  3. Smooth
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23
Q

Skeletal (striated) muscle:

A

Enables movement of limbs and other parts of the skeleton

Connected to bone
- via tendons (origin)
- via tendons (insertion)

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24
Q

Cardiac (striated) muscle:

A

The pump in the circulation (heart)

Functional syncytium

Intrinsic pacemaker activity

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25
Q

Smooth muscle:

A

Functional syncytium

Around many hollow internal organs

26
Q

Striated meaning?

A

STRIPPED

= Muscle tissue in which the contractile fibrils in the cells are aligned in parallel bundles, so that their different regions form stripes visible in a microscope

27
Q

Skeletal muscle structure

A

Muscle cells connected to following muscle cell

Consists lot of cells - many nuclei

Forms fibres and group together = muscles

28
Q

How are muscle fibres connected?

A

Sheet of connective tissue

29
Q

What is the structure of a muscle fibre?

A

Plasma membrane

Transverse tubule

Myofibril

Terminal cisterna

Tubules

30
Q

Plasma membrane of muscle fibre

A

Sarcolemma

31
Q

Transverse tubule

A

T-tubule

32
Q

Terminal cisterna of…

A

Sarcoplasmic reticulum (smooth reticulum)

33
Q

Tubules of…

A

Sarcoplasmic reticulum (smooth reticulum)

34
Q

Myofibrils

A

Contractive elements of the mucsle

35
Q

4 key proteins of myofibril:

A

1) Myosin
2) Actin
3) Troponin
4) Tropomyosin

36
Q

Which protein is the thick filament?

A

Myosin - single thick filament (2 heads - LIKE two golf clubs)

37
Q

Actin _____ filaments

A

thin

38
Q

Troponin + Tropmyosin

A

Balls that are bound to the filaments

39
Q

What is troponin’s role?

A

When Ca2+ bonds to troponin it causes conformational change to tropmyosin which is tightly bound to actin

This unwinds the tropomyosin from the myosin which exposes the myosin binding site which is on the actin = causes CONTRACTION

(allows the myosin to bind to the actin)

40
Q

How do thick and thin filaments join together in myofibril?

A

Actin thin filaments are joined/ bridged with Myosin thick filaments (one every other)

Z disk goes parallel to Actin filaments (this is what keeps them together)

41
Q

What is the H zone

A

Where there is a gap (NO overlap) between the Actin and Myosin filaments = at rest (this is when there is no contraction)

Therefore thinner

42
Q

what happens to H zone when there is a contraction?

A

Overlapping of both filaments; Actin + Myosin are sliding across each other

Will reach point where Actin from either side will reach each other

43
Q

Cross bridge cycling:

A

Tight Binding in the Rigor state

Myosin filament BINDS to G-actin molecule

44
Q

4 steps of cross bridge cycling

A

1) ATP binds to myosin
2) Myosin hydrolyzes ATP
3) Power stroke
4) Myosin releases ADP

45
Q

1) ATP binds to myosin

A

Myosin releases Actin

46
Q

2) Myosin hydrolyzes ATP

A
  • Energy from ATP rotates the myosin to the coked position
  • ADP and Pi remain bound
  • Myosin binds weakly to actin
47
Q

3) Power stroke

A
  • begins when tropomyosinmoves off the binding site.
48
Q

4) Myosin releases ADP

A

Myosin releases ADP at the end of the power stroke

49
Q

WHEN: ADP released - the myosin head tightly bound to actin

A

The cycle is ready to begin once
more as a new ATP binds to myosin

50
Q

How does depolarisation lead to contraction?

A

Excitation-Contraction- Coupling

51
Q

Excitation-Contraction- Coupling : what does it need?

A
  1. Need AP & Calcium

which; AP triggers calcium release
ACTION POTENTIAL

52
Q

Events at the NMJ:

A

1) Resting state
2) AP arrival - release od Ach (DEpolarisation of pre-synapse)
3) Depolarisation of MEP - wave of depolarisation passes down fibre
4) Contraction - muscle fibre REpolarises

53
Q

Depolarisation:

A

Ca2+i - contraction link

54
Q

Calcium - Ca2+

A

intracellular signal for contraction

55
Q

Summarise of the steps:

A

1) Action potential in axon

2) Ach release at terminal

3) Muscle contraction

56
Q

Does skeletal muscle spontaneously contract??

A
  • Skeletal muscle is not spontaneously contractile
  • Nerve supply cut – flaccid paralysis
57
Q

Activity at the neuromuscular junction is acetylcholinergic:

A

1) ACh formed in the synaptic terminal

2) Generated by ChAT

3) Packaged into vesicles

4) Released into the synaptic cleft

5) Calcium entry causes fusion of synaptic vesicles

6) Ach bind to Nicotinic ACh Receptors

7) Non-Bound = Broken down by Ach- esterase

8) Choline taken up to be reused

58
Q

Sites of pharmacological interference

A

Acetylcholine are packed into synaptic vesicles

ACh transferase - Ca2+ into the neurovascular junction and Na+ out into the motor end-plate (in the muscle fibre)

59
Q

Botox and vesicular

A
  • Botulinum toxic from clostridium botulinum bacteria
    inhibitor of vesicular fusion:
  • Alters proteins required for vesicular fusion with the presynaptic membrane
60
Q

How does botox work? (P

A

Stops vesicles from forming

No contraction in skin

PMP-101 (53 decks)

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