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Semester 3 > PBL 7 > Flashcards

PBL 7 Flashcards

1
Q

How is dopamine produced?

A

From L-DOPA, catalysed by L-DOPA decarboxylase

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2
Q

What are the two main dopaminergic containing structures within the brain?

A

Substantia Nigra

Ventral tegmental area (VTA)

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3
Q

What happens when dopamine binds to its D1 receptor?

A
  • activation of G alpha S type G protein
  • activation of adenylate cyclase
  • formation of cAMP
  • stimulation of dynorphin precursor (PPE-B)
  • excitation of the direct pathway in basal ganglia
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4
Q

What happens when dopamine binds to its D2 receptor?

A
  • activation of Gi/o G protein couple receptor
  • inactivation of adenylyl cyclase by inhibition
  • inhibition of formation of cAMP
  • inhibition of production of enkephalin precursor (PPE-A)
  • inhibition of the indirect pathway
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5
Q

What structures comprise the striatum?

A

Caudate and putamen

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6
Q

Name the 3 functional divisions of the striatum and where in the basal ganglia they are located?

A

1) Sensorimotor - dorsal and lateral
2) Associative - medial
3) Limbic/ventral - ventral and medial

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7
Q

What are the 3 functional subdivisions of the cerebellum and what structures are they composed?

A

Neocerebellum - anterior and posterior cerebellar hemispheres and dentate nucleus
Paleocerebellum - vermis, paravermis, globose and emboliform nuclei
Archicerebellum - flocculonodular lobe and fasting also nucleus

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8
Q

What are the different functions of the 3 functional divisions of the cerebellum?

A

Neocerebellum - muscle coordination
Paleocerebellum - maintains muscle tone and posture
Archicerebellum - balance

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9
Q

What is the difference between bradykinesia, hypokinesia and akinesia?

A

Bradykinesia - slow movement
Hypokinesia - lessened movement
Akinesia - absence of movement

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10
Q

What kind of gait is seen in Parkinson’s disease?

A

Shuffling gait

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11
Q

What is the mean age of onset for Parkinson’s disease?

A

60 years

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12
Q

What is the characterising tremor of Parkinson’s? What type of tremor is it?

A

Pill rolling

Resting tremor

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13
Q

What are the possible environmental causes of Parkinson’s?

A

MPTP neurotoxin

  • found in synthetic opoid MPPP
  • found in paraquat (weed killer)
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14
Q

What are the genetic factors that can cause Parkinson’s?

A

Recessive genes - Parkin

Dominant genes - SNCA, LRRK2

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15
Q

What are the changes to the basal ganglia during Parkinson’s disease?

A

Reduced excitatory signals in direct pathway - direct pathway is underactive
Reduced inhibitory signals in indirect pathway - indirect pathway is overactive
= net effect - reduced movement

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16
Q

What kind of behavioural impairment can occur in Parkinson’s disease?

A

Cognitive disturbances - decreased dopamine in associative pathways
Impulsive behaviours - decreased dopamine in limbic pathways
Depression/anxiety - due loss of monoamines (noradrenaline)

17
Q

Why is L-DOPA therapy good initiation and then deteriorates?

A

This is due to disease progression. As more nigrostriatal neurons are lost there are fewer dopamine receptors to be stimulated by dopamine.

Increased dyskinesia (unwanted movement) side effects due to a narrowing of the therapeutic window

18
Q

What are the “on-off” effects of L-DOPA?

A

Where within seconds people may change from being fairly mobile to being severely immobile.

This may be due to the dopaminergic neruons capability to store dopamine and the brain becoming more dependant on exogenous dopamine

19
Q

What is end of dose dyskinesia?

A

Where levodopa induced dyskinesia (unwanted movements) become more common over time

20
Q

What are the mechanisms of the motor complications in advanced Parkinson’s?

A

As dopamine neruonal levels wear off in the brain, dopamine given in therapy is handled by other neurons e.g, 5-HT neurons. As these are not specialised to handle dopamine, it is released in a pulsatile manner.

21
Q

What is deep brain stimulation and how is it used to treat Parkinson’s?

A

Where electrode devices are implanted in part of the basal ganglia to counteract the aberrant signalling in Parkinson’s.

It greatly reduces involuntary movements and shortens the off part of the on-off effects

22
Q

What is chorea?

A

Abnormal involuntary hyperkinetic movement due to an overactive direct pathway in the basal ganglia and an under active indirect pathway

Semester 3 (13 decks)

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