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Human Physiology 2 > Disorders of nervous system > Flashcards

Disorders of nervous system Flashcards

1
Q

What is the definition of a neurodegenerative disease?

A

Disorder in which particular neurons degenerate leading to loss of function of that region of the central or peripheral nervous system

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2
Q

What are some neurodegenerative diseases?

A

Alzheimer’s
Parkinson’s
Huntington’s
Sclerosis

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3
Q

What are the main neurons lost in Alzheimer’s?

A

Cholinergic neurons

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4
Q

What is the first part of the brain usually affected by Alzheimers?

A

Hippocampus and then spreads to frontal lobe (communication) and parietal (orientation)

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5
Q

What are plaques of Alzheimers made of ?

A

extracellular deposits of degenerating nerve processes and a core of insoluble beta-amyloid proteins

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6
Q

What are neurofibrillary tangles?

A

In Alzheimers disease, they are found in cell bodies and axons and are composed of hyperphosphorylated protein tau, which is involved in assembly of microtubules

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7
Q

What are the genetic factors involved in Alzheimers ?

A

Mutations of the genes encoding amyloid precursor protein (APP) and presenilin (involved in processing amyloid )

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8
Q

What are possible environmental factors involved in Alzheimers?

A

high levels of aluminium in soil

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9
Q

Where is APP usually found?

A

Membrane of neurons

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10
Q

What enzyme cleaves APP into fragments?

A

Secretase enzyme (alpha,beta,gamma). Presenilin is catalytic component of gamma-secretase

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11
Q

What fragment of APP is particularly toxic to neurons?

A

A(beta)42

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12
Q

What are the current drugs used for Alzheimers?

A

Acetylcholineesterase inhibitors that prevent breakdown of ACh, or ACh receptor agonist that mimic ACh and alleviate symptoms

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13
Q

What are future possibilities for Alzheimers treatment?

A

Inhibition of secretase enzyme

Antibody-base drugs designed to target toxic Abeta

Vaccine to improve immunity to toxic Abeta

Stem cells to replace lost neurons

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14
Q

What causes Parkinson’s disease?

A

The degeneration of dopaminergic neutrons of the nigrostriatal pathway

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15
Q

What is one of the features of Parkinson’s?

A

The accumulation of dense deposits (Lewy bodies) in the nigrostriatal neurons that impair their function or destroy them

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16
Q

What is the nigrostriatal pathway?

A

Neurons that project from the substantia ingrate to the striatum (basal ganglia)

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17
Q

What could be an environmental factor for Parkinson’s?

A

Exposure to MPTP which is oxidised by the monoamine oxidase found in dopaminergic neurons, into MPP+ . This then binds to Neuromelanin and inhibits etc killing the cell

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18
Q

What are the genes involved in Parkinson’s?

A

SNCA gene (park1) which encodes alpha-synuclein and PARK2 gene that encodes the protein parkin

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19
Q

What is the role of alpha-synuclein ?

A

It is a nerve terminal protein and a toxic form of it is found in Lewy bodies

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20
Q

What is the role of Parkin?

A

An enzyme component of ubiquitin-proteasome pathway responsible for removal of damaged proteins

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21
Q

What are the treatments for Parkinson’s?

A
  • L-DOPA , precursor of dopamine
  • Inhibitors of enzyme monoamine oxidase which degrades dopamine
  • DEEP BRAIN STIMULATION: surgical procedure where electrons are implanted in the brain and connected to a stimulator places somewhere else in the body. These impulses override the abnormal electrical signals caused by the disease
22
Q

What is the most common demyelinating disorder?

A

Multiple sclerosis

23
Q

Is MS acquired or inherited?

A

Acquired

24
Q

What are some possible causes of MS?

A
  • Infectious agent: Epstein-Barr virus mostly
  • Immune-mediated: antibodies produced against myelin components (molecular mimicry)
  • Genetic Factors: mostly genes involved in MHC
25
Q

How is MS diagnosed?

A
  1. Nerve conduction test (record speed of electrical conduction)
  2. Sampling of CSF by lumbar puncture for presence of white blood cells or antibodies
  3. Magnetic Resonance Imaging to look for abnormalities and scarring in white matter
26
Q

How is MS treated?

A

Drugs like β-interferons that alleviate symptoms and progression by acting at the Level of immune system

Exercise, physiotherapy and diet

27
Q

Is Guillan-Barrè syndrome acute or chronic?

A

Acute

28
Q

What is another name for Guillan-Barrè syndrome ?

A

Acute inflammatory demyelinating polyneuropathy

29
Q

What neurons does Guillan-Barrè affect?

A

Somatic motor (paralysis and respiratory problems)

Sensory neurons (loss of sensation)

Autonomic neurons ( blood pressure and cardiac arrhythmia)

30
Q

How does Guillan-Barrè happen?

A

When antibodies triggered by a viral infection attack components of Schwann cell myelin

31
Q

What is a treatment for Guillan-Barrè ?

A

Immunoglobulins intravenously and plasmapheresis (plasma exchange)

32
Q

Is Charcot-Marie-Tooth Disease inherited ?

A

Yes

33
Q

In which way is CMT usually inherited?

A

Autosomal (dom/rec.) in 80-90% of cases

34
Q

What is the main gene affected in autosomal cases of CMT?

A

Peripheral myelin protein-22 (PMP-22) involved in development and maintenance of Schwann cell myelin

Rare cases due to mutations in myelin protein zero (P0) gene which encodes an adhesion molecule important for compaction of PNS myelin

35
Q

What is the main gene affected in cases of CMTX?

A

Mutation in gene connexion 32 which encodes the channel proteins of gap junctions

36
Q

Where is Cx32 found?

A

Schwann cells

37
Q

What does Cx32 do?

A

Forms reflexive gap junctions between the layers of myelin membrane surrounding peripheral axons

38
Q

What are symptoms of myasthenia disorders?

A

Weakness and fatiguability affecting ocular, facial, bulbar, respiratory and limb muscles

39
Q

How do myasthenic disorders arise?

A

From defects in any of the components of synaptic transmission and may arise from autoimmune or genetic basis

40
Q

Two examples of autoimmune myasthenic disorders?

A

Myasthenia gravis (MG) and Lambert-Eaton Myasthenia (LEMS)

41
Q

What happens in MG?

A

Auto-antibodies attack protein subunits of nicotinic ACh receptor

42
Q

Is MG presynaptic or postsynaptic defect?

A

Postsynaptic

43
Q

How does MG affect nicotinic ACh receptor?

A

Autoantibodies either block transmitter binding,

increase the rate of receptor degradation

or destroy the postsynaptic membrane leading to cell lysis

44
Q

What happens in LEMS?

A

Antibodies attack voltage gated Ca++ channels in the motor neuron presynaptic terminal, reducing ACh release as Ca++ is trigger for exocytosis

45
Q

Is LEMS presynaptic or postsynaptic defect?

A

Presynaptic

46
Q

Examples of Congenital myasthenic syndromes

A
  1. Ach Receptor deficiency
  2. Congenital myasthenic syndrome with Episodic apnea (CMSEA)
  3. End plate Acetylcholinesterase deficiency
47
Q

What happens in ACh receptor deficiency ?

A

Mutations in genes that encode subunits of nicotinic ACh receptor leading to fewer receptors or with altered properties (POSTSYNAPTIC)

48
Q

What happens in Congenital myasthenic syndrome with Episodic apnea (CMSEA)?

A

Mutations in choline acetyltransferase, the ACh synthetic enzyme leading to insufficient production of neurotransmitters (PRESYNAPTIC)

49
Q

What happens in End Plate Acetylcholinesterase Deficiency?

A

Mutations in acetylcholinetransfferase, the ACh degradative enzyme leading to insufficient production of neurotransmitter (SYNAPTIC DEFECT)

50
Q

What can LEMS be associated with?

A

Lung cancer or other cancers because of cell mimicry

51
Q

What are some symptoms of CMT?

A
  • motor deficits (weakness of leg, foot and hand muscles)

- sensory loss ( unable to perceive temperature, pain..)

Human Physiology 2 (5 decks)

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