NBS 655 > Module 2 > Flashcards

Module 2 Flashcards

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1
Q

What is the developmental origin of microglia?

A

Microglia are derived from the yolk sac, unlike most other glial cells which come from the ectoderm.

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2
Q

Why can’t regular immune cells access the brain?

A

The blood-brain barrier prevents most immune cells in the rest of the body from entering the brain.

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3
Q

What is the primary immune function of microglia?

A

They act as resident phagocytotic immune cells of the CNS, comparable to macrophages, engulfing pathogens and debris.

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4
Q

What pathogens can microglia protect against?

A

Bacteria, viruses, fungi, and parasites.

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5
Q

How do microglia interact with T-cells?

A

They can act as antigen-presenting cells (APCs) to activate T-cells by displaying captured antigens.

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6
Q

What types of debris can microglia clear after injury?

A

They remove damaged neurons and glial cells caused by ischemia or neuronal degeneration.

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7
Q

What signaling molecules do microglia release?

A

Cytokines and chemokines that mediate neuroinflammation and attract immune cells.

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8
Q

What role do microglia play in synaptic plasticity?

A

They prune synapses by engulfing unnecessary parts, shaping neuronal plasticity.

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9
Q

What is the developmental origin of macroglia?

A

Macroglia are derived from the ectoderm (with some ependymal cells and pericytes from the mesoderm).

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10
Q

What types of glial cells are considered macroglia in the CNS?

A

Astrocytes, oligodendrocytes, ependymal cells, and pericytes.

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11
Q

What types of glial cells are considered macroglia in the PNS?

A

Schwann cells and satellite cells.

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12
Q

What are radial glial cells (RGCs)?

A

Neural progenitor cells that guide migrating neurons during development.

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13
Q

What path do RGCs guide neurons along?

A

From the ventricular zone through the intermediate zone to the cortical plate and outer pial surface.

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14
Q

What is the long-term fate of many RGCs?

A

They differentiate into neurons or other glial cells later in cortical development.

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15
Q

What protein identifies astrocytes?

A

GFAP (Glial Fibrillary Acidic Protein), an intermediate filament protein.

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16
Q

What are the two main types of astrocytes and where are they found?

A

Protoplasmic astrocytes in gray matter (short, thick processes) and fibrous astrocytes in white matter (long, thin processes).

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17
Q

How do protoplasmic astrocytes support neurons?

A

They are near neuronal cell bodies and blood vessels, transporting nutrients and interacting with synapses.

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18
Q

How do fibrous astrocytes support white matter?

A

They support axons and oligodendrocytes, providing nutrients and survival support.

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19
Q

What is the role of astrocytic end-feet in nutrient transport?

A

They attach to blood vessels, use transporter proteins to move ions, amino acids, sugars, and vitamins across the BBB, and release them into extracellular fluid.

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20
Q

How do astrocytes regulate cerebral blood flow?

A

Astrocytic end-feet release factors that act on pericytes to control capillary dilation.

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21
Q

What is a tripartite synapse?

A

A synapse where astrocytes surround pre- and post-synaptic neurons, modulating transmission and neurotransmitter levels.

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22
Q

How do astrocytes regulate the chemical environment of synapses?

A

They control extracellular glutamate and potassium levels, and may release gliotransmitters like ATP.

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23
Q

How do astrocytes promote neuronal survival?

A

By releasing neurotrophic factors into the extracellular fluid.

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24
Q

What happens when astrocytes become reactive?

A

They form reactive glia and glial scars after injury, which impede axonal regeneration in the CNS.

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25
What fluid do ependymal cells produce?
They produce cerebrospinal fluid (CSF) and extracellular fluid.
26
What barrier do ependymal cells form?
The Blood-CSF Barrier (BCSFB).
27
What is the choroid plexus?
A component of the ventricles made of specialized ependymal cells and capillaries that synthesize CSF.
28
What functions does the choroid plexus perform?
It filters blood, produces CSF, and removes metabolic waste, foreign substances, and excess neurotransmitters from CSF.
29
Where are pericytes located?
They line the outside of CNS capillaries and interact with vascular endothelial cells.
30
What is the role of pericytes in the BBB?
They assist in controlling tight junctions between vascular endothelial cells, maintaining the BBB.
31
How do pericytes control blood flow?
They act as contractile cells regulating vasodilation and thus the rate of blood flow.
32
What is the main function of oligodendrocytes?
To provide myelin sheaths that insulate CNS axons, with one oligodendrocyte myelinating up to 50 axons.
33
Why are oligodendrocytes important for long axons?
They protect axons from shearing forces and improve conduction speed.
34
How do oligodendrocytes affect axonal regeneration?
They produce inhibitory molecules that block axonal regrowth after CNS injury.
35
Where are Schwann cells found?
In the PNS, near axons of motor and sensory neurons.
36
How does myelination differ between Schwann cells and oligodendrocytes?
Each Schwann cell myelinates only one axon segment, while an oligodendrocyte can myelinate up to 50 axons.
37
What is the regenerative role of Schwann cells?
They promote axonal regeneration after injury, enabling reinnervation of original targets such as muscle or skin.
38
Where are satellite cells located?
In the ganglia of the PNS, surrounding the neuronal cell bodies of sensory and autonomic neurons.
39
What functions do satellite cells provide?
They supply nutrients, give structural support, and regulate the microenvironment, similar to astrocytes in the CNS.
40
What is an antigen presenting cell (APC)?
A cell that captures antigens and displays them to T-cells to activate immune responses (examples: microglia, macrophages, dendritic cells, B cells).
41
What is axon shearing?
Also called diffuse axonal injury (DAI), occurs when brain tissue is torn or stretched from sudden acceleration or deceleration.
42
What is the brain parenchyma?
Functional tissue of the brain, including neurons, dendrites, axons, synapses, and glial cells.
43
What are cytokines?
Immuno-modulating molecules that regulate immune responses, cell growth, and differentiation.
44
What are chemokines?
Chemotactic cytokines that attract immune cells to particular sites in the body.
45
What is ischemia?
Condition where blood flow to the brain is reduced or blocked, depriving it of oxygen and nutrients, such as during a stroke.
46
What are neural progenitor cells (NPCs)?
Specialized cells that can divide and differentiate into different types of neurons and glial cells.
47
What is programmed cell death?
Also known as apoptosis, a regulated and orderly form of cell death that maintains tissue health.
48
What are myelinating cells?
Cells that create myelin sheaths to insulate axons: oligodendrocytes in the CNS and Schwann cells in the PNS.
49
What molecules can astrocytic end-feet transport across the BBB?
Ions, amino acids, sugars, water-soluble vitamins, and other small molecules.
50
How do astrocytes regulate extracellular glutamate?
By absorbing and controlling glutamate concentrations at glutamatergic synapses.
51
How do astrocytes regulate extracellular potassium?
By buffering extracellular K+ levels at synapses to maintain excitability.
52
What gliotransmitter can astrocytes release?
ATP, which can bind to neuronal receptors and modulate synaptic transmission.
53
Where are ependymal cells located?
They line the ventricles of the brain and the central canal of the spinal cord.
54
What type of junctions do choroid ependymal cells form?
Tight junctions, creating the Blood-CSF Barrier (BCSFB).
55
What are choroid ependymal cells also called?
Choroid epithelial cells, since they line the choroid capillaries.
56
Besides myelination, how else do oligodendrocytes support axons?
They nourish axons and help maintain their survival.
57
Do Schwann cells only myelinate axons?
No, they can also support non-myelinated axons in peripheral nerves.
58
How are satellite cells functionally similar to astrocytes?
Both provide nutrients and regulate the microenvironment of neurons.
59
What is the cortical plate?
A temporary structure during development that forms the mature cerebral cortex.
60
What is the ventricular zone?
An embryonic layer of stem cells lining the brain’s ventricles that produces neurons and glia.
61
What is the intermediate zone?
A transient developmental layer between the ventricular zone and cortical plate filled with migrating cells.
62
What is the outer pial surface?
The outermost boundary of the cerebral cortex where neurons migrate during development.
63
What is extracellular fluid (ECF)?
Fluid outside cells including blood plasma, interstitial fluid, lymph, and CSF; important for nutrient and waste transport.
64
What are ganglia?
Groups of neuronal cell bodies in the PNS surrounded by satellite cells.
65
What is neuronal degeneration?
The progressive loss of structure and function of neurons, often leading to cell death.
66
What is the mesoderm?
The middle germ layer; forms muscles, bones, connective tissue, internal organs, and some glial cells like ependymal and pericytes.
67
What is the ectoderm?
The outermost germ layer that forms the nervous system and skin.
68
What are macrophages?
Immune cells that perform phagocytosis and stimulate immune responses; microglia are CNS-resident macrophages.
69
What is phagocytosis?
The process by which a cell engulfs and digests pathogens, debris, or dying cells.
70
What is apoptosis?
A form of programmed cell death that is regulated and essential for healthy development.
71
What is ischemia?
A condition of reduced or blocked blood flow, depriving tissues of oxygen and nutrients, often caused by stroke.
72
What is the choroid plexus?
A network of capillaries and specialized ependymal cells that produce cerebrospinal fluid (CSF).
73
What is cerebrospinal fluid (CSF)?
Fluid found in the ventricles, central canal, and subarachnoid space; cushions and nourishes the brain.
74
What are cytokines?
Small signaling molecules that regulate immune responses, inflammation, and cell communication.
75
What are chemokines?
A subclass of cytokines that attract immune cells to specific locations in the body.
76
What is an antigen presenting cell (APC)?
A cell that processes and displays antigens to T-cells to trigger immune responses; examples include microglia, dendritic cells, macrophages, and B-cells.
NBS 655
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