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Neurology > Class 3 > Flashcards

Class 3 Flashcards

1
Q

What is neuralgia (glia)?

A

In recent years, neuroscientists call glia sleeping giant of neuroscience because of important role they play in information processing.

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2
Q

What are the 5 kinds of neuralgia (glia)?

A
  1. Schwann Cells
  2. Oligodendrocytes
  3. Microglia
  4. Astrocytes
  5. Ependymal Cells
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3
Q

What are Schwann cells?

A

Act to provide layers of protective membrane that insulate axons called myelin in PNS.

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4
Q

What is myelin?

A

Protective layer around axon. Is mixture of proteins & lipids forming an insulating sheath around many nerve fibres. Myelin increases speed at which impulses are conducted.

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5
Q

What are Peripheral nerves?

A

Composed of bundles of parallel nerve axons, embedded within multilayers of connective tissue.

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6
Q

The endoneurium is CT that _____________________________.

A

Wraps around the axons and is bundled into fascicles by the perineurium

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7
Q

What is perineurium?

A

Sheath of CT surrounding a bundle (fascicle) of nerve fibres within nerve

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8
Q

What is epineurium?

A

Outermost layer of connective tissue surrounding
peripheral nerve. Usually surrounds multiple nerve fascicles as well as blood vessels which supply nerve. Smaller branches of these blood vessels penetrate into perineurium.

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9
Q

A peripheral nerve requires an ___________________________ to function.

A

uninterrupted blood supply

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10
Q

A peripheral nerve requires an uninterrupted blood supply to function. This is supplied only by a delicate capillary network in the endoneurium called the _____________________.

A

vasa nervorum

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11
Q

Is it possible to have areas of local ischemia without involving entire peripheral nerve?

A

It’s possible to have areas of local ischemia without involving entire peripheral nerve. Can lead to multitude of issues

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12
Q

What is Ischemia?

A

Deficient supply of blood to body part, is due to obstruction of inflow of arterial blood, as by narrowing of arteries by spasm or disease.

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13
Q

When we talk about PNS nerve injury, We think about ________________________.

A

Wallerian degeneration

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14
Q

What is Wallerian Degeneration?

A

• Active process of degeneration, results when nerve fibre in PNS is cut or crushed. Axon distal to injury (farther from the neuron’s cell body) degenerates. Proximal axons are able to regrow as long as cell body is intact.
• Macrophages & Schwann cells migrate to area of damage, clear away debris, & release neurotrophic factors that stimulate re-growth.
• Schwann cells grow in ordered columns & create band of so called Büngner cells that direct axon growth back to correct targets.

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15
Q

What are Neurotrophic Factors?

A

Factors able to stimulate regrowth

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16
Q

What are the three varying degrees of nerve injury depending on severity?

A

• Neuropraxia
• Axonotmesis
• Neurotmesis

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17
Q

What is Neuropraxia?

A

Mildest form of nerve injury. It’s classified as transient conduction block of motor or sensory function without nerve degeneration. Loss of motor function is most common finding. Patients are usually able to fully recover within period of weeks to months.

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18
Q

What is Axonotmesis?

A

Axons and their myelin sheath are damaged, but surrounding connective tissue remain intact. Complete recovery time of injury varies from 1 week to 6 months.

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19
Q

What is Neurotmesis?

A

Occurs when a nerve, along with it’s surrounding connective tissue becomes completely disconnected. While partial recovery may occur, complete recovery is impossible

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20
Q

What are Oligodendrocytes?

A

Act to provide layers of protective membrane that
insulate axons called myelin in CNS.

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21
Q

A disease that attacks oligodendrocytes is _________________.

A

multiple sclerosis (MS)

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22
Q

What is multiple sclerosis (MS)?

A

Autoimmune disorder of CNS & optic nerves. Disease attacks myelin. Myelin replacement occurs, but process becomes unreliable & eventually stops.

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23
Q

Unlike PNS injury damage to CNS is not followed by
_______________________.

A

extensive regeneration

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24
Q

T/F there is treatment for recovering human nerve function
after injury to CNS.

A

There is currently no treatment for recovering human nerve function after injury to CNS.

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25
Q

The environment within CNS, especially following trauma, counteracts the repair of _______________ and ______________.

A

myelin and neurons

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26
Q

Many factors contribute to formation of a “glial scar” across which ________________________________________.

A

axons cannot grow.
(CNS axons have been proven to regrow in permissive environments)

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27
Q

Another serious problem is that morphology & functional properties of CNS system neurons are highly complex. This is why these neurons ______________________________.

A

for the most part, these neurons cannot be replaced.

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28
Q

Examples of Demyelination Signs & Symptoms (Without Reference To Specific Diseases) include?

A

• Ataxia
• Parasthesia
• Dysarthria
• Diplopia

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29
Q

What is Ataxia?

A

• Presence of abnormal, uncoordinated movements.
• An unsteady, staggering gait is described as an ataxic gait because walking is uncoordinated

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30
Q

What is Parasthesia?

A

• Abnormal sensation, typically “pins & needles”, caused chiefly by pressure on or damage to peripheral nerves
• Formication is type of paresthesia; feeling of insects crawling across or underneath one skin. Can also result from stimulant intoxication or withdrawal from drugs (cocaine, MDMA aka ecstasy) or alcohol withdrawal.

31
Q

What is Dysarthria?

A

• Occurs when speech muscles are weak or are hard to control
• Often causes slurred or slow speech that can be difficult to understand.

32
Q

What is Diplopia (double vision)?

A

Person sees two images of a single object

33
Q

What is Microglia?

A

Resident macrophage immune cells of CNS. Microglia facilitate & coordinate responses between peripheral immune system and brain.

34
Q

What are Macrophages?

A

Immune system cells that recognize, engulf, & destroy
infected, damaged, or dead cells.

35
Q

What are Cytokines?

A

Substances released by cells & affect behavior of other cells.

36
Q

Pro and anti inflammatory cytokines can be transported into brain via _______________________ or by _____________________.

A

blood (humoral pathway) or by vagus nerve (neural pathway)

37
Q

What is Neuroinflammation?

A

Driven by microglial cells show few if any of cardinal
signs of peripheral inflammation/pain, heat, redness, swelling & loss of function (SHARP).

38
Q

T/F microglia can pump out neuron damaging pro-inflammatory factors, or they can pump out anti- inflammatory factors that are neuroprotective.

A

Recent evidence suggests microglia can pump out neuron damaging pro-inflammatory factors, or can pump out anti inflammatory factors that are neuroprotective.

39
Q

Cytotoxic secretion by microglia, for example glutamate, is
aimed at destroying ______________________________________.

A

infected neurons, viruses, and bacteria, but can also
cause large amounts of collateral damage to healthy neurons.

40
Q

Consequences of microglial hyper-activation following
immune challenge are _________________________________.

A

exaggerated neuroinflammation, sickness behavior, depressive like behavior, & cognitive deficits.

41
Q

In the young, microglia activation helps…

A

• Mount appropriate responses following peripheral infection.

42
Q

During microglia activation, In the aged…

A

•
•There is increase in pro inflammatory cytokines and increase of inflammatory receptors on microglia.
• These microglia are referred to as primed, reactive, or sensitized.
• Activation is amplified with prolonged issues & even bladder infections can have serious consequences in aged.
• This results in “self-perpetuating neurotoxicity” or reactive microgliosis.
• May be an underlying mechanism of progressive neuron damage across numerous neurodegenerative diseases, regardless of instigating stimuli.

43
Q

What are Astrocytes?

A

Most abundant glia in brain, mainly responsible for regulating chemical content of extracellular space. Restrict spread of neurotransmitters in brain, remove neurotransmitters from synaptic cleft & vasoconstrict vasodialate brain blood vessels, there by contributing to blood brain barrier.

44
Q

What is the blood brain barrier?

A

Limits harmful substances in brain by contributing to complex filtration system which alters permeability of
brain capillaries. Is not perfect system, some toxic substances (alcohol, amphetamines, metals), can make its way through, while some important therapeutic drug agents cannot make it through.

45
Q

Astrocytes can recycle _______________________________.

A

neurotransmitters released during synaptic transmission.

46
Q

Astrocytes can signal each other using ____________________.

A

ATP via gap junctions

47
Q

What are features of Astrocytes, Hydration and Cognition?

A

• Water is an essential body nutrient and its homeostasis is crucial for life.
• Early in evolution of animals, marine creatures were surrounded by water, but survival on dry land required built-in, “portable” water.
• Brain consists of about 80% water.
•Astrocytes store most of brain’s CNS intracellular water.
• Function as storage tanks for times of water scarcity

48
Q

What are key features of Dehydration and its risks?

A

• Common medical problem in seniors.
• Contributing factor for delirium which is strong risk factor for dementia.

49
Q

Delirium is typically caused by _________________________.

A

acute illness or drug toxicity and is often reversible

50
Q

Demetia is typically caused by ___________________________.

A

anatomic changes in brain, has slower onset, & is generally irreversible

51
Q

T/F The process of aging seems to undo the evolutionary advantage of “portable water”

A

True - The process of aging seems to undo evolutionary advantage of “portable water” as elderly individuals are known to lose their fluid reservoirs by age related decrease in both muscle mass (huge reservoir for body) & astrocytes.

52
Q

T/F Water has been known to play major role in protein
conformational dynamics.

A

True - Water has been known to play major role in protein
conformational dynamics. To become biologically active new proteins must fold along specific axes like paper in ancient Japanese art of origami.

53
Q

Misfolded protein aggregates have now been shown to be involved in many _______________________________.

A

neurocognitive disorders

54
Q

Astrocytes have processes which wrap around neurons to form _________________________.

A

“tripartite synapse” (presynaptic neuron, postsynaptic neuron, & astrocyte).

55
Q

Tripartite synapse contributes to ________________________.

A

neural plasticity

56
Q

What is Neuroplasticity (brain plasticity)?

A

Refers to structural changes in brain in response to new situations, environment, thinking, emotions, as well as to changes that result from bodily injury.

57
Q

Chronic (persistent) pain is an unfortunate product of _________________________.

A

neural plasticity

58
Q

T/F Pain processing is simply a relay of signals from body to brain.

A

False - Pain processing is NOT simply a relay of signals from body to brain.

It’s a complex system that can be up and down regulated by number of different factors.

59
Q

Neuroplasticity can lead to?

A

1) Hyperalgesia (heightened response to painful stimuli) and
2) Allodynia (painful response to normally non-painful stimulus).

60
Q

What is Hyperalgesia?

A

Heightened response to painful stimuli

61
Q

What is Allodynia?

A

Painful response to normally non-painful stimulus

62
Q

What are Ependymal Cells?

A

Line fluid-filled ventricles within brain & play role in directing cell migration during brain development, & filter blood creating cerebral spinal fluid.

63
Q

What is Cerebrospinal fluid (CSF)?

A

Clear, colorless liquid that acts to lessen the impact of a blow to head.

*Cerebrospinal fluid (CSF) circulates in subarachnoid space protecting it transporting hormones.

64
Q

Under some pathological conditions, CSF builds up in brain, a condition called ____________________.

A

hydrocephalus

65
Q

What is a lumbar puncture (spinal tap)?

A

Also called spinal tap, is an invasive outpatient procedure used to remove a sample of CSF from subarachnoid space. Lumbar puncture can help diagnose serious infections, such as meningitis, multiple sclerosis, or cancers of brain or spinal cord.

66
Q

Under normal circumstances the _________________ adheres to the skull and arachnoid membrane with no intervening spaces.

A

Dura Mater

67
Q

Where can hematomas occur?

A

Hematomas can occur in subdural & epidural spaces.

68
Q

What is a hematoma?

A

Localized mass of extravasated blood, usually clotted.

• resulting increase in intracranial pressure can lead to fatal brain tissue damage.

69
Q

Symptoms of a cerebral hematoma include?

A

Severe headache, deterioration of consciousness & motor dysfunction.

70
Q

A blow to the skull can create an __________________________.

A

epidural hematoma between skull and dura if it causes fracture that transects a blood vessel

71
Q

Subdural hematoma is more common in elderly brains because of the ______________________.

A

shrinkage that occurs with aging

• Shrinkage stretches & weakens veins & are more likely to break in elderly, even after minor head injury.

72
Q

What is a chronic subdural hematoma?

A

An “old” collection of blood & blood breakdown products between surface of brain & dura.

• Blood leaks from veins slowly over time.
• Trepanation is treatment used for epidural & subdural hematomas. Is surgical intervention in which hole is drilled in skull. (Also performed by physician through fingernail or toenail to relieve pain associated with subungual hematoma).

73
Q

What is Trepanation?

A

• Treatment used for epidural & subdural hematomas.
• Is surgical intervention in which hole is drilled in skull. (Also performed by physician through fingernail or toenail to relieve pain associated with subungual hematoma).

Neurology (12 decks)

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