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Neuro > Injury and repair to the CNS > Flashcards

Injury and repair to the CNS Flashcards

1
Q

What are 8 mechanisms of injury to the CNS?

A

Stroke (ishaemic), hypoxia, developmental, inflammatory, neurodegenerative, traumatic, infection, tumour.

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2
Q

What type of brain cells are affected by injury?

A

All- glial, neurons, blood brain barrier and CSF.

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3
Q

What is a craniectomy and the most common cause?

A

Where part of the skull is removed to give room for inflammation or oedema, therefore the swelling doesn’t affect the brain tissue.

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4
Q

What is a stroke?

A

an acute loss of blood supply that damages the region supplies by the blocked artery.

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5
Q

How long does it take for neuronal cells to die post ischaemia?

A

6-8 minutes.

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6
Q

How long does it normally take vascular occlusions to clear?

A

24 hours, they clear themselves. However too late at 2 million neurons die per minute in this time.

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7
Q

What is hypoxia brain injury? What areas does it affect most?

A

reduction of the whole brain oxygenation. Affects the most metabolically active areas (grey matter of cerebral cortex and basal ganglia.)

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8
Q

What is multiple sclerosis?

A

Disease where inflammation causes degeneration and neural dysfunction results

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9
Q

What happens to brain substance in neurodegenerative diseases?

A

whole brain substance shrinks. Neurons either get cut - Axotomy. or lose their normal input - denervation.

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10
Q

What are the consequences of axon death? (upstream and downstream)

A

Retrograde degeneration - cell body dies via apoptosis.

Anterograde degeneration. wallerian degeneration where the distal axon dies.

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11
Q

What is an important factor in the re growth of nerve cells?

A

Time - the longer it takes to clear dead cells the less chance of regrowth.

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12
Q

Why do cells in the PNS regrow but not in the CNS?

A

In the PNS severed axons regrow if their nerve sheath is intact.
Macrophages aid clear the damaged cells and create the optimal healing environment. Schwaan cells assist in regeneration.
In the CNS clean up of dead cells is slow and oligodendrocytes inhibit regeneration.

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13
Q

What is the role of myelin in the regeneration of nerve cells?

A

Provides a guide tube for the sprouting axon.

In development guides the sprouting axon to its destination.

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14
Q

What are the 5 classifications of nerve injury?

A

Grade 1 - neuropraxia.
Grade 2 - axonotmesis
Grade 3 - neurotmeses with preservation of perineurium
Grade 4 - neurotmesis with preservation of epineurium
Grade 5 - neurotmesis with complete transection of nerve trunk.

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15
Q

Outline grade 1 nerve injury.

A

Neuropraxia- conduction disruption. Intact axon and preserved supportive structures.

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16
Q

Outline grade 2 nerve injury.

A

Axonotmesis - disrupted axon with intact endoneurin - the delicate connective tissue surrounding the myelin sheath.

17
Q

Outline grade 3 nerve injury.

A

Neurotmesis with preservation of perineurium. Disruption of the supporting structures. Perineurium is the sheath of connective tissue surrounding the fascicles of nerves. Endoneurium disrupted.

18
Q

Outline grade 4 nerve injury

A

Neurotmesis with preservation of the epineurium. Epineurium is the outermost layer of dense irregular connective tissue surrounding peripheral nerves.

19
Q

Outline grade 5 nerve injury.

A

Neurotmesis with complete transection of the nerve trunk

20
Q

What is glial scarring?

A

Scars that form post CNS injury due to reactive proliferation of astrocytes and microglia.

21
Q

How does glial scarring aid recovery?

A

regenerates a tissue barrier after blood brain barrier compromise and promotes revascularisation of the injured brain.

22
Q

How does glial scarring prevent healing?

A

astrocytes secrete developmental inhibitors that prevent axon regrowth and regeneration.

23
Q

What is neurogenesis? In an adult mammalian brain where is there evidence of this.

A

Birth of new neurons. Hippocampus and just below the lateral ventricles.

24
Q

What is neurorehabilitation?

A

As brain injuries are irreversible there is a focus on treatment - with restoration and maximisation of loss of function. Involves learning which will change synaptic strength in different regions of the brain.

25
Q

What is neural plasticity?

A

Ability of the brain to change structurally and functionally as a result of environmental input. - brain changes structurally with learning.

26
Q

What is somatotopy?

A

Point to point correspondence of an area of the body to a particular point in the CNS.

27
Q

What is a homonculus?

A

Structural representation of motor and sensory supply of the brain to different regions of the body - those with a larger supply have a larger region of cortex suppplying to them.

28
Q

Why are functions of the brain subject to neural plasticity?

A

Functions of the brain are often shared, therefore if one area of the brain supplying a specific function is damaged, the other areas supplying will increase their activity to ensure there is as little change as possible.

29
Q

Why would functions of the brain be changed?

A

Peripheral and central injury,
Electrical stimulation,
learning and experience.

30
Q

What is compensation? (in terms of brain damage)

A

Where one area of the brain takes over the functions of the other.

31
Q

How does compensation com e about?

A

Presynaptic neurones sprout more terminals and form additional synapses
Neurons reorganise

32
Q

Give examples of neural plasticity after: stroke, becoming blind and hemispherectomy.

A

Stroke - recovery of functions.
Blind people use their visual cortex to learn braille and other non visual functions,
Post hemispherectomy children learn language and intellectual preservation.

33
Q

What is transcranial magnetic stimulation?

A

A coil is applied to the head above the left pre frontal cortex (responsible for mood regulation). The magnetic fields are concentrated here and stimulate small electrical currents in the brain - which cause neurotransmitter release.

34
Q

What are stem cells? Give two types

A

undifferentiated meiotically active cells which regenerate and self renew.
Embryonic - totipotent
Adult - pluripotent.

35
Q

Uses of stem cells?

A

cell based therapies - regenerative or reparative. therapeutic cloning and gene therapy.

36
Q

What are induced pluripotent stem cells? What does it require?

A 
Adult cells (from skin cells) which are reprogrammed to become pluripotent. 
Requires 4 over expressing genes.
37
Q

What is stem cells transplantation?

A

Where the cells of neurons and oligodendrocytes are related, however little evidence this happens.

38
Q

What is the bystander effect?

A

Neuroprotective state - aids recovery instead of breakdown of neurons and oligodendrocytes:
Anti inflammatory, anti apoptic, and delivery of trophic factors.

39
Q

What are brain machine interfaces?

A

Neuroprosthetics, where implants stimulate brain activity and release of signals and NTs. Most common is the cochlear implant.

Neuro (11 decks)

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