CNS and Cell Types

Question 1

Where do action potentials originate?

Answer 1

The axon hillock

Question 2

Where do inputs to cells come from?

Answer 2

Dendrites

Question 3

Where do outputs from cells go?

Answer 3

Through axons

Question 4

What are the 2 types of synapses?

Answer 4

Electrical
Chemical (majority)

Question 5

Where are excitatory synapses concentrated?

Answer 5

On dendritic spines

Question 6

What neurons are lost in Motor Neuron Disease?

Answer 6

Motor neurons

Question 7

What neurons are lost in Huntington’s Disease ?

Answer 7

Medium spiny GABA neurons

Question 8

What is an upper motor neuron?

Answer 8

first-order neurons which are responsible for carrying the electrical impulses that initiate and modulate movement.

They are large, excitatory neurons which are glutaminergic and have long projection pyramidal cells

Question 9

What are striatal interneurons?

Answer 9

Small, inhibitory GABAergic neurons

Question 10

What are oligodendrocytes?

Answer 10

Myelinating cells of the CNS (the PNS has schwann cells which are myelinating)
They insulate axon segments are allow rapid nerve conduction
Provide metabolic support for axons
Myelin sheath segments are interrupted by nodes of ranvier- part of neurotransmission where the impulse travels along the axon
A single oligodendrocyte can myelinate multiple axons

Question 11

What is the myelin sheath?

Answer 11

Formed by wrapping of axons by oligodendocyte processes
They are highly compacted
Myelin specific proteins cna be used as ‘markers’

Question 12

What are microglia?

Answer 12

Resident immune cells of the CNS
Proliferate at sites of injury
Upon acitvatio, retract processes and become “amoeboid” and motile

Question 13

What are the functions of microglia?

Answer 13

Immune surveillance
Phagocytosis- debris/microbes
Synaptic plasticity- pruning
Good (M2) glia and bad (M1) glia

Question 14

What are astrocyes?

Answer 14

Star like cells
Most numerous glial cells in the NCS
Part of the BBB

Question 15

What is the function of astrocytes?

Answer 15

Envelop synapses & blood vessles
Metabolic support
NVC
Proliferate (increase) in disease
Development
Regulate ion/metabolites

Question 16

What are radial glia (specialised astrocytes) important for?

Answer 16

Important for brain development

Question 17

What are Bergmann glia (specialised astrocytes) imporant for?

Answer 17

Cerebellum

Specialized, unipolar glial cells featuring cell bodies situated in the Purkinje cell layer and radial fibers passing through the molecular layer

Question 18

What are Muller cells important for?

Answer 18

Retina

The principal glial cell of the retina. They form architectural support structures stretching radially across the thickness of the retina and are the limits of the retina at the outer and inner limiting membrane respectively.

Question 19

MND symptoms are due to a loss of ?

Answer 19

Motor neurons

(astrocytes and microglia are invovled in MND but there is no loss of them, they proliferate in the diseases)

Question 20

MND spinal cord shows pathological changes in what?

Answer 20

Motor neurons (loss), microglia (increase), and astrocytes (increase)

Question 21

Pathological CNS lesions in MS involved what?

Answer 21

Neurons, Oligodendrocytes, and T lymphocytes

Question 22

Acute symptoms in MS reflect dysfunction of what?

Answer 22

Neurons

Question 23

Abundance of neural cell bodies is called what?

Answer 23

Nuclei

Question 24

Axons are gathered together in what?

Answer 24

Tracts

Question 25

Tracts that cross the midline are called what?

Answer 25

Commissures

Question 26

What is abundant in neural cell bodies and processes in the CNS?

Answer 26

Grey matter

Question 27

What is abundant in myelinated tracts & commissures in the CNS?

Answer 27

White matter

Question 28

Where are cell bodies and supporting cells located in the PNS?

Answer 28

Ganglia e.g. dorsal roota gnalgia

Question 29

What is the BBB composed of?

Answer 29

Endothelial cells, astrocytes and pericytes

Question 30

What are the features of the BBB?

Answer 30

Endothelial tight junctions
Astrocyte endfeet
Pericytes
Continuous basement membrane that lacks fenestrations
Specific transporters for glucose water and essential ions

Question 31

What are ependymal cells?

Answer 31

Epithelial-like cells which line ventricles and the central canal of the spinal cord
The facilitate CSF production, flow and absorption

Question 32

What is choroid plexus?

Answer 32

A network of blood vessels and cells in the ventricles (fluid-filled spaces) of the brain. The blood vessels are covered by a thin layer of cells that make cerebrospinal fluid.