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MBBS > 205 NS - Biochemistry > Flashcards

205 NS - Biochemistry Flashcards

1
Q

What does bloody CSF indicate?

A

Traumatic lumbar puncture

Subarachnoid haemorrhage

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2
Q

What does turbid/milky CSF indicate?

A

Presence of cells
Presence of microbes
Increased protein level
Presence of lipids (milky)

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3
Q

Where should lumbar puncture be done?

A

L3/L4 space or L4/L5 space

  • because spinal cord ends at L2, avoid puncturing it
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4
Q

What can CSF analysis indicate?

A 
CNS infections
Demyelinating diseases
CNS malignancy
Hemorrhage in CNS
Autoimmune disorders
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5
Q

How long should CSF analysis be done within?

A

Within 1 hour after sample collected

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6
Q

What does [glucose] in CSF depend on?

A

[glucose] in blood
rate of glucose transport into the CSF (efficiency of GLUT)
Metabolic rate of CNS

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7
Q

What is the glucose gradient along the neuraxis?

A

[Glucose] decreases from ventricular to lumbar fluid

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8
Q

What’s the function of CSF?

A

Protection
Buoyancy
Excretion of waste products
Regulation of cranial content volume

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9
Q

Excitatory neurotransmitters

A

Leads to depolarization

Glutamate
Aspartate
Serotonin
ATP

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10
Q

Inhibitory neurotransmitter

A

Leads to hyperpolarization

Glycine
GABA

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11
Q

Synthesis of acetylcholine

A

Choline + acetyl-CoA

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12
Q

Metabolism of acetylcholine

A

After released into synaptic cleft by exocytosis, hydrolyzed by acetylcholinesterase (AChE)

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13
Q

2 major constellations of cholinergic neurons

A

Basal forebrain constellation (sleep & wakefulness)

Dorsolateral pontine tegmental constellation (memory & learning)

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14
Q

What receptors mediate sympathetic effects?

A

Adrenergic

Exception: sweat gland (muscarinic)

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15
Q

What receptors mediate parasympathetic effects?

A

Muscarinic

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16
Q

Myasthenia Gravis

A

Autoimmune disorder

Leads to skeletal muscle weakness due to the development of autoantibody against AChR at NMJ

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17
Q

Synthesis of glutamate

A

Glutamine is synthesized to glutamate by glutamine synthetase (GS)

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18
Q

Metabolism of glutamate

A

Glutamate is broken down to glutamine by glutaminase (GA)

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19
Q

Excitotoxicity

A

Prolonged stimulation of neurons by excitatory a.p. results in neuronal death or injury

20
Q

Synthesis of GABA (γ-aminobutyric acid)

A

Glutamate is synthesized to GABA by glutamic acid decarboxylase (GAD)

21
Q

Metabolism of GABA (γ-aminobutyric acid)

A

After release, GABA is taken up into presynaptic terminal & glia
GABA is converted to glutamate by mitochondrial GABA transaminase (GABA-T)

22
Q

What leads to epilepsy?

A

Lack of GABA in certain parts of brain

23
Q

Which vitamin does glutamic acid decarboxylase (GAD) require?

A

Vitamin B6

24
Q

Synthesis of catecholamines

A

Tyrosine → L-DOPA → dopamine
dopamine → norepinephrine
norepinephrine → epinephrine

25
Q

Synthesis of dopamine

A
  1. Tyrosine enters neuron by active transport
  2. Tyrosine converted into DOPA by tyrosine hydroxylase
  3. DOPA converted to dopamine by DOPA decarboxylase
26
Q

Metabolism of dopamine

A

Reuptake

Destroyed by COMT (catechol-O-methyltransferase) & MAO (monoamine oxidase)

27
Q

What is used as index of function of dopaminergic neurons?

A

Homovanillic acid (HVA)

  • because it’s a major metabolite that is produced by action of MAO and COMT on dopamine
28
Q

Where are dopaminergic neurons located in the brain? (3)

A

Substantia nigra - coordination of movement, degeneration associated w Parkinson’s

Ventral tegmental area - pleasure & reward; motivation & emotion

Hypothalamic arcuate nucleus - regulate secretion of prolactin & maternal behavior

29
Q

What causes schizophrenia?

A

Too much dopamine

30
Q

What causes Parkinson’s disease?

A

Too little dopamine

31
Q

Schizophrenia vs Parkinson’s disease

A

Schizophrenia - too much dopamine

Parkinson’s - too little dopamine

32
Q

Cocaine drug addiction

A

The ventral tegmental area to limbic structures involve emotional reinforcement & motivation

Cocaine binds to dopamine transporter & blocks reuptake of dopamine → increased extracellular level of dopamine

33
Q

Synthesis of norepinephrine

A

Dopamine β-hydroxylase (DBH) converts dopamine → norepinephrine

34
Q

Synthesis of epinephrine

A

Phenylethanolamine N-Methyltransferase (PNMT) converts norepinephrine → epinephrine

35
Q

Metabolism of norepinephrine & epinephrine

A

Same as dopamine:

Reuptake
Destroyed by COMT (catechol-O-methyltransferase) & MAO (monoamine oxidase)

36
Q

Norepinephrine is involved in?

A

Sleep & wakefulness, attention, feeding behaviour

37
Q

Mania

A

Too much norepinephrine

38
Q

Depression

A

Too little norepinephrine

39
Q

Norepinephrine & epinephrine are neurotransmitters of ______ system.

A

sympathetic

40
Q

Synthesis of serotonin

A
  1. Tryptophan enters brain by active uptake
  2. Hydroxylated by tryptophan hydroxylase → 5-hydroxytryptophan
  3. Decarboxylated by aromatic a.a. decarboxylase → serotonin
41
Q

Metabolism of serotonin

A

After release, serotonin reuptake by serotonin transporter or MAO

42
Q

Serotonergic neurons

A

Raphe nuclei of medulla, pons, upper brainstem

  • regulation of pain, mood, sleep
43
Q

How does endorphin act as analgesic?

A

Endorphins are released by pituitary gland & hypothalamus to block pain perception
It binds to opiate receptors located on presynaptic membrane & block release of substance P - neurotransmitter involved in pain responses

44
Q

Subarachnoid haemorrhage

A

Characterized by bleeding & pooling of blood between the innermost 2 membranes (arachnoid membrane & the pia mater)

Occur when bridging blood vessels/dural sinuses rupture

45
Q

Most common cause of subarachnoid haemorrhage

A

Aneurysm

- when walls of blood vessels are weakened & dilates

46
Q

What does fibrin clot in CSF sample indicate?

A

Protein level very high

47
Q

How to differentiate bloody CSF sample of traumatic lumbar function of subarachnoid hemorrhage?

A

After centrifugation, observe supernatant

Clear → blood contamination

Yellowish → subarachnoid haemorrhage

MBBS (28 decks)

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