Week 11/2 Degen Disord Et Al. Flashcards

0
Q

Any tumor in the brain, benign or malignant, is harmful.
▪ Tumors are damaging to the brain because:

A
  • the tumor occupies space and compresses the brain
    tissue.

- the tumor invades the surrounding tissue as it grows
and destroys cells in its path.

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1
Q

A tumor is ?
▪ A benign tumor has ?
▪ If the tumors infiltrates the surrounding tissue, it is ? (i.e. cancerous).

A

A tumor is a uncontrollable growth of cells that serves no useful function.
▪ A benign tumor has a distinct border between the tumor cells and the surrounding tissue (i.e. it is encapsulated).

▪ If the tumors infiltrates the surrounding tissue, it is malignant (i.e. cancerous).
Malignant tumors give rise to a process of metastasis in which tumor cells travel through vascular system and grow elsewhere in the body.

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2
Q

tumor of the cells of the meninges is called a?

A

meningioma
It has displaced the right side of the brain.
The right ventricle is almost completely occluded.
Non malignant, benign in x.

Low other types names in text?

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3
Q

Glioma are the most ?

A

common and serious type of tumor. Grow from glial cells
Different specific types:
- Astrocytoma (astrocytes)
- Ependymoma (ependymal cells that line the ventricle)
- Medulloblastoma (cells in the roof of the fourth ventricle)
- Oligodendrocytoma (oligodendrocytes)

Extract and then try to destroy with radiation.

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4
Q

Seizure Disorders (Epilepsy)
▪ A seizure is period of sudden, excessive activity of cerebral neurons.

A

▪ If the cells constitute the motor system, the seizure will cause a wild, uncontrollable activity of the muscles called a convulsion.

Types of seizures?
▪ Partial seizures have a definite focus and remain localised.

▪ Diagnosis relies on EEG; epilepsy is associated with bursts of high amplitude EEG spikes which occur during an attack.

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5
Q

Types of partial seizures?

A

▪ Partial seizures have a definite focus and remain localised.
- Simple partial seizures involve changes to consciousness.
- Complex partial seizure lead to loss of consciousness.

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6
Q

What of seizure happens during rem sleep

A

Act out dreams or interact with ordinary ppl.

Can report experience.

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7
Q

Generalised Type Seizures: Grand Mal

Explain.
note has focus,

A

Generalised seizures are widespread involving most of the brain.
▪ A grand mal seizure is the most severe of all seizures. Preceding the seizure, the patient will experience:
changes in mood sudden jerks of muscular activity before waking
an aura; a peculiar sensation or psychological change
(e.g. a bad smell, hallucination, bright lights; euphoria).

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8
Q

What are the Grand Mal Seizure phases?

A

-Clonic Convulsion
▪ The grand mal seizure begins with the tonic phase:
- muscles contract forcefully
- arms outstretch rigidly
- patient makes an involuntary cry (patient is
unconscious)
- patient holds a rigid posture for 15 seconds

▪ In the clonic phase:
- muscles tremble
- muscles jerk convulsively (quickly at first)
- eyes roll
- face is contorted (tongue may be bitten)
- sweating and salivation
- after 30 seconds, muscles relax; breathing begins
again
- patient falls into an exhausted sleep

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9
Q

Generalised Seizures: Petit Mal
Aka?
EEG pattern?

A

▪ Children have spells of petit mal (absence) seizures:
- - - -
- -
vacant look
blink eyes repeatedly
unresponsive

can occur up to 100 times a day; they can be disruptive to normal day to day activities and often go undiagnosed

seizures frequently cease at adolescence

The EEG of a petit mal seizure shows a bilateral symmetrical pattern of a 3-per second electrical discharge.

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10
Q

Seizures have many causes including?

A

▪ The most common causes of seizures:
- scarring produced by stroke, injury or irritating effect of a
growing tumor.
- alcohol or barbiturate withdrawal (this can be fatal). Increase inhibit ation over firing

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11
Q

Seizures have serious consequences

A

▪ Almost half of the patients who have seizures will show evidence of damage to the hippocampus

▪ A single episode of status epilepticus (during which the patient experiences a series of seizures without regaining consciousness) causes excessive glutamate release during the seizure.
▪ Thus, NMDA receptors are involved in seizures.

Too much calcium, enters cell

Causes supsensitity, essp. Alcohol abuse, increase nmda.
Known as up regulation. Over acticity of glutamate

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12
Q

Seizures are related to NMDA receptor activity

A

▪ NMDA receptors control calcium channels.
▪ Alcohol blocks NMDA receptors.
▪ Long-term suppression of NMDA receptors (due to alcohol abuse) causes supersensitivity (up-regulation).
▪ When an alcoholic suddenly stops drinking, the suppressed NMDA receptors suddenly rebound.
▪ The increased activity of NMDA receptors cause seizures.

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13
Q

Cerebrovascular Disorders aka?

A

▪ Strokes are sudden-onset cerebrovascular disorders that cause brain damage.

▪ A hemorrhagic stroke is caused by bleeding within the brain. It occurs when a cerebral blood vessel ruptures due to high blood pressure.

▪ Ischemic strokes are caused by a disruption of the blood supply to an area of the brain. These are three main types

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14
Q

There are three main causes of ischemia:

A
  • a blood clot (thrombus) that forms in the blood vessels (e.g air bubble, tumor, fat).
  • an embolus, carried through the bloodstream, lodges itself preventing the flow of blood.
  • an arteriosclerosis is caused by thickening of the arteria
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15
Q

Stroke-induced release of glutamate kills neurons

A

▪ Sodium-potassium channels stop functioning due to lack of oxygen and glucose.
▪ The neuron membrane depolarises which causes excessive glutamate release.
▪ Excessive glutamate triggers excessive influx of Na+ and Ca2+ ions by way of NMDA receptors.
▪ Excessive Na+ and Ca2+ is toxic to the cell.
• excessive Na+ causes the cell to absorb water and swell.
• inflammation attracts white blood cells which obstruct capillary walls.
• Damaged mitochondria produce free radicals

See process photo

16
Q

Stroke Treatments for you to know?

A

▪ Administer an anticoagulant to prevent blood clotting (e.g. warfarin). Used mainly for thrombotic cases.

▪ Desmetoplase is an anticoagulant derived from a enzyme found in vampire bats. It can be injected directly into the brain. It can reduce stroke related clinical symptoms 9 hours after the stroke.

▪ Dissolve blood clot to re-establish blood circulation (e.g. tPA: tissue plasminogen activator). However, tPA can be toxic if it crosses the blood brain barrier.

▪ Reduce risk factors: high blood pressure, cigarette smoking, diabetes, high cholesterol.

17
Q

Developmental Disorders: Toxic Chemicals

A

▪ The presence of toxic chemicals during pregnancy (e.g rubella) can lead to abnormal fetal development and cause mental retardation.

▪ Chronic alcohol consumption during pregnancy can lead to fetal alcohol syndrome. Issue d facial deformation and abnormal brain dev. Drink during critical period. Uh oh!

18
Q

Developmental Disorders: Inherited Metabolic Disorders

A

▪ “Errors of metabolism” refer to genetic abnormalities in which the recipe for a particular enzyme is in error so the enzyme cannot be synthesized.

▪ Children with phenylketonuria (PKU) are unable to convert phenylanine into tyrosine (both are amino acids).
- Excessive phenylanine interferes with myelinization of
neurons after birth.
- Place child on low-phenylamine diet otherwise severe
mental retardation

▪ Tay-Sachs disease is caused by an accumulation of waste products in the brain.
- Lysosomes lack an enzyme that normally breaks down
waste products.
- The lysosomes get larger as waste accumulates causing
eventual swelling of the brain.
Symptoms! See book, incl. seizure?

19
Q

Developmental Disorders: Downs Syndrome

A

▪ Downs syndrome is a congenital disorder (present at birth).
▪ It is caused NOT by a faulty gene, but because of an extra
21st chromosome.
▪ The syndrome is associated with the mothers age; a higher risk of downs syndrome with age.
▪ Down syndrome is easily recognisable:
What happens after 30? Brain degenerate, thin dulcimer, ad

20
Q

Down syndrome is easily recognisable by?

A
  • round heads
  • thick, protruding tongues. Keep mouth open.
  • stubby hands, low set ears, slanting eyes, short stature.
  • slow to learn
  • brains are 10% lighter; sulci and gyri are smaller and
    simpler.
  • small frontal lobe and thin superior temporal gyrus
21
Q

▪ Transmissible spongiform encephalopathy (TSE) is a contagious brain disease which gives the brain a sponge- like appearance. They are fatal.

A
  • BSE: Bovine spongiform encephalopathy (‘mad cow
    disease’)
  • Creutzfeldt-Jakob disease (transmitted to humans from
    cows) chd
  • Kuru (humans only), b/c eat brains
  • Scrapie (sheep only)

▪ Symptoms include:
- dementia (loss of memory and personality; hallucinations)
- speech impairment
- ataxia; changes in gait, rigid posture
- seizures

22
Q

TSE is caused by a proteins called ?

A

prions (protein infectious agents).
▪ Healthy prions (PrPc) are found in membranes where they play a role is synaptic function.
▪ The infectious protein (PrPSc) is identical to the healthy protein.
▪ PrPc and PrPSc differ in their 3d shape; the difference is in the way the protein is folded.
▪ Once the misfolded PrPSc is introduced into the cell, it causes healthy PrPc to misfold aswell.
▪ PrPSc’s are resistant to proteolytic enzymes and heat.

23
Q

Mad cow, not reversed by overheating nor

A

Proteoleic enzymes. So resistant to prions poor quality,

24
Q

Degenerative Disorders: Parkinson’s Disease

A

Parkinson’s disease (PD) is caused by degeneration of the nigrostriatal system.

Surviving dopaminergic neurons show Lewy bodies: abnormal circular structures in the cytoplasm.

▪ PD is associated with a mutation of a gene located on chromosome 4.
The gene normally produces α- synuclein which is involved in synaptic transmission in dopaminergic neurons

Abnormal accumulation of α-synuclein is toxic to the cell and causes aggregations in dopaminergic neurons. Lewy bodies consist of these aggregations.

25
Q

Treatments for Parkinson’s Disease

A

▪ L-DOPA replenishes the brain of its lost dopamine. This does not work indefinitely.

▪ In 1982; seven people in north California (mid twenties) were hospitalised for displaying dramatic clinical symptoms.
- total paralysis, no speech, constant drooling, eyes open
with fixed stare, shuffling with slow gait. ➔ Parkinsonian

▪ They had all taken a a synthesized heroin (demoral) which contained MPTP (1-methyl-4-phenyl-1,2,3,6- tetrohydropyridine).

▪ Primates treated with MPTP show cell loss in substantia nigra.

▪ Deprenyl blocks the effects of MPTP.

MPt model of Parkinson’s disease

26
Q

Surgical Treatments for Parkinson’s Disease

A

▪ Transplantation of fetal tissue (rare)
- tissue obtained from substantia nigra of aborted human
fetuses and implanted into the striatum.
- not a routine procedure as many patients complain of
painful, involuntary movements (dyskinesias)

▪ A potential source of dopamine cells could come from cultures of stem cells
- stem cells are undifferentiated cells that have the ability
to develop into a variety of cell types.

▪ Destruction of the the internal division of the globus pallidus (pallidotomy) or the subthalamic nuclei.

27
Q

Alzheimer’s disease (AD) is characterised by progressive memory loss and other mental functions.
What are the neural correlates of Alzheimer’s Disease

A

▪ AD produces severe degeneration of the hippocampus, entorhinal cortex, subbiculum, association cortices of the frontal and temporal lobes, the nucleus basalis (ACh), raphe nuclei (5- HT) and the locus coeruleus (NA).

Two types of cellular abnormalities:
▪ Amyloid plaques consist of a dense protein core (β-amyloid) surrounded by degenerating axons and dendrites

▪ Neurofibrillary tangles comprise dying neurons that contain accumulations of twisted filaments of phosphorylated tau protein.

28
Q

Accumulation of β-amyloid in brains of Alzheimer patients

A

▪ The accumulation of amyloid plaques is caused by a defective form of β- amyloid.

▪There are two form of β- amyloid: a long and short form.

▪ In AD, the abnormally high concentration of the long β- amyloid causes them to misfold and aggregate which cause brain degeneration.

29
Q

Genetic causes of AD

A

▪ The mutation of the gene APP (amyloid precursor protein) leads to familial AD.
- This mutation is also responsible for tangle deposits.
- Mutation in the gene for tau deposits produce tangles only
and are typically associated with frontotemporal dementia.

▪ A mutation in the gene for apolipoprotein E (ApoE) increases the risk of late-onset AD by interfering with the removal of the long form of β-amyloid.

Brains of Downs Syndrome also contain β-amyloid deposits. Thus, the 21st chromosome may be involved in the production of this protein.

Seems less imp. This slide!

30
Q

Other neurological disorders to be aware of

A

▪ Amyotrophic lateral sclerosis attacks the spinal cord and cranial nerve motor neurons. Symptoms: spasticity, exaggerated stretch, muscle weakness and eventual paralysis.

▪ Multiple sclerosis is an autoimmune demyelination disease: myelin sheaths are attacked by the immune system. Normal neural transmission is interrupted.

▪ Korsakoff’s syndrome is caused by chronic alcoholism which leads to thiamine (vitamin B1) deficiency.

▪ Infectious disorders (encephalitus, rabies, meningitis)