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1 NAS > Lectures 6-10 > Flashcards

Lectures 6-10 Flashcards

1
Q

What is the definition of the motor unit?

A

a somatic efferent plus all the muscle fibres it supplies

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2
Q

What is the neruomuscular junction?

A

The interface between the neuronal and muscular compartments

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3
Q

What is a fasciculus comprised of?

A

muscle fibres, and then myofibril

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4
Q

What kind of muscle fibres are somatic?

A

skeletal

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5
Q

What is the sheath of the myofibril?

A

the endomysium

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6
Q

What surrounds the fascicle

A

the perimysium

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7
Q

What runs between muscle fascicles?

A

The neurovascular bundle

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8
Q

Name 5 types of skeletal muscle

A 
Convergent
Strap
Circular
Fusiform
Pennated (Unipennate, Bipennate, Multipennate
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9
Q

What is in the middle of the H zone?

A

the m line

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10
Q

What kind of lower motoneurones are there?

A

alpha, beta, or gamma

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11
Q

What three things do the characteristics of the motor unit allow for?

A

unifrorm force throughout muscle
It allows the nervous system to control the rate and speed of contraction
Muscle to contract within the central axis of the attachments of the muscle

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12
Q

What determines the motor unit properties?

A

The type of efferent supplying it

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13
Q

What is a stretch reflex?

A

The connection between the lower motoneurone and an afferetnt of muscle length sense organ
monosynaptic stretch reflex (synapse between sensory and motor neruones)

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14
Q

What is the sginificance of the muscle stretch reflex?

A

the template nerual circuit for all motor units, and allows for minimal neural circuits

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15
Q

Which motor units are recruited first?

A

those with the smallest cell bodies and the lowest threshold for firing action potentials (lowest force)
Larger units are recruited on a progressively increasing scale of firing threshold.

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16
Q

How many molecules of ACh are requireed to open an AChR?

A

2

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17
Q

Where are Na+ VGC’s found in the NMJ?

A

deep in the folds of the post-synapse

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18
Q

What happens to the EPP?

A

The end plate potential decays as it gets further away from the end plate

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19
Q

How is Ca2+ released from the SR?

A

DHP receptors (Ca2+ VGC) detect the action potential in the t-tubule and open the Ca2+ Ryanodine release channels

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20
Q

What is Myesthenia Gravis?

A

an autonimmune disease of nAChR, at the NMJ.

It is treated using AChE inhibitors.

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21
Q

What are the 3 components of the motor unit?

A

The motoneurone
The NMJ
The skeletal muscle fibres

22
Q

What are damaged muscle symptoms akin to?

A

lower motoneurone signs

23
Q

What happens in reinnervation?

A

Sometimes nerves may reinnervate other effector organs

24
Q

What is Polio Myelitis?

A

Polio virus infection of neurone soma of the ventral horn

25
Q

What are the two variants of Polio?

A

1 - kills upper and lower motoneurones

2 - kills lower motoneurones

26
Q

What is Motoneurone disease?

A

spontaneous genetic apoptosis of motoneurones, although extraocular motoneurone and anal sphincter motoneurones are unaffected

27
Q

What does Botulinum Toxin do?

A

It can make food toxic - paraysis and death.

It de[letes the presynaptic terminal of the NMJ

28
Q

What can Botulinum Toxin be used for?

A

controlling muscle spasms

29
Q

What are nerve gases?

A

organophosphates, blocking AChE in NMJ

30
Q

What are the 4 properties of a good LA?

A

Reversible

Blocks Ap in nociceptive neurones

31
Q

What is nociception, and what is their significance with LA?

A

sensory receptors generate AP’s to the brain, their Na+ VGC’s are targeted

32
Q

What are the common features of LA’s?

A

have an aromatic ring (makes it lipid soluble)
an ester(faster)/amide linkage
an amide end group

33
Q

What are the lengths of duration of Procaine, Lidocaine, Prilocaine, and Bupivacaine?

A

Procaine - short (too short for modern use)
Lidocaine - medium
prilocaine - medium
Bupivacaine - long

34
Q

What happens to the equilibrium when the environment is more alkaline?

A

the PoE will shift left, decreasing the amount of ionised LA (therefore, at pH 7.41, we have more of the ionised form)

35
Q

What does the LA block?

A

The ionised LA blocks open channels (NA+ VGC’s) from within the axon

36
Q

What effect does inflammation or infection have on LA

A

It decreases the pH, decreasing LA+, and hence reducing its effectiveness

37
Q

Which motoneurones are the most easily affected by LA?

A

A-delta and C as they have the smallest diameter

38
Q

What might injection of LA into blood vessels cause?

A

cadiac arrest or vessel dilation

39
Q

What might be administered with LA’s to minimise risks of side-effects?

A

vasoconstrictors (they also increase duration of action)

40
Q

Are reflexes somatic or autonomic?

A

BOTH

41
Q

What 3 functions do reflexes serve?

A

protection
postural control
homeostasis

42
Q

Expand on the term integration in the reflex arc

A

Interneurones in the CNs are inhibitory neurones.
They enable modulation - permiting somatic overriding of reflexes.
They allow the brain to know what is going on in the reflex

43
Q

What is a myotatic reflex?

A

simple stretch reflexes
Use muscle spindles (stretch receptive), more stretches stimulate greater muscle contraction
Inhibitory interneurones reduce contraction of antagonistic muscle

44
Q

What kind of reflex arc would a myotatic reflex use?

A

monosynaptic

45
Q

What happens to Golgi tendon organs?

How do they work?

A

They are stretched as the tendon is stretched

The interneurone releases inhibitory transmitter to the motoneruone, reducing contraction.

46
Q

What kind of reflex would Golgi tendon organs stimulate?

A

polysynaptic, inverse myotatic reflexes

47
Q

What are golgi tenon organs important for?

A

preventing damage due to overwork and permits fine control in the hands

48
Q

Do all somatic reflexes use prioprioreceptors?

A

No, not the withdrawal effect

49
Q

What is the crossed extensor reflex

A

With the withdrawal reflex, posture may also be adjusted to combat forward momentum, for example.

50
Q

NMJ: What does Ca2+ trigger in the pre-synaptic knob?

A

Binds to Ca2+ sensor called a synaptogram, stimulating a conformational change and hence vesicle fusion

1 NAS (12 decks)

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