neurons

Question 1

3 types of CNS cells

Answer 1

1. ) neurons
2. ) Glia
3. ) Others

Question 2

Features of neurons

Answer 2

• Have dendrites/cell body/axon/axon terminals
• Axon terminals communicate with other axons
• Communicate electrically via synapses

Question 3

Histology

Answer 3

• Large neurons: speckly pattern: missel body

- H&E: stains nucleic acids blue and proteins red

Question 4

What is LFB

Answer 4

LFB (luxol fast blue): stains myelin

Question 5

What is CV

Answer 5

Stains Nissl (RER)

Question 6

Types of neurons

Answer 6

1. ) chemical

2. ) electrical

Question 7

Features of electrical synapses

Answer 7

• Have connexons and connecins

Question 8

Features of chemical synapses

Answer 8

• Rich in mitochondria

-

Question 9

How does synaptic transmission take place?

Answer 9

• Influx of calcium allows neurotransmitters to be released/fused on the membrane

Question 10

Dendritic spines

Answer 10

• Synapses are concentrated here

Question 11

Synaptic plasticity

Answer 11

• They are dynamic structures
• Neural plasticity: basis of learning and memory
• Spinal remodelling linked to neural activity

Question 12

Features of neuronal heterogeneity

Answer 12

Heterogenous for::

1. ) size
2. ) morphology
3. ) neurotransmitters

Question 13

Features of upper motor neurons

Answer 13

• Large
• Excitatory
• Glutamatergic
• Long projection pyramidal cells
• Use GABA

Question 14

Oligodendrocyte features

Answer 14

• Myelinating cells of CNS
• Myelin insulates axons segments + enables rapid nerve conduction
• Provides metabolic support for axons]- Myelin sheath segments interrupted for nodes of ranvier

Question 15

Oligodendrocyte features

Answer 15

• Myelinating cells of CNS
• Myelin insulates axons segments + enables rapid nerve conduction
• Provides metabolic support for axons]- Myelin sheath segments interrupted for nodes of ranvier]
• can myelinate multiple axons

Question 16

Myelin sheath features

Answer 16

• Multiple layers of membrane
• 70% lipid and 30% protein
• Myelin specific proteins e.g. MBP involved in compaction

Question 17

Mircoglia features

Answer 17

• Immune cells of CNS
• Originate from yolk sac projenitors
• In ‘rest’ they are highly ramified/motile processes (2-3 mm/min_
• In activation: retract processes and become more rounded
• proliferate at sites of injury (phagocytic)

Question 18

Functions of microglia

Answer 18

1. ) Immune surveillance
2. ) Phagocytosis
3. ) Synaptic plasticity: pruning

Question 19

Astrocyte features

Answer 19

• most numerous of the glial cells
• Highly heterogenous
• Common maker is GFAP

Question 20

Astrocyte morphologies

Answer 20

1.) Fibrous: white matter/contact blood vessels/pia/nodes od ranvier

Question 21

Astrocyte functions

Answer 21

• developmental: radial glia
• structure: define brain micro-architecture
• envelope synapses: tripartite synapse
• homeostatic: buffer K+
• Metabolic support

Question 22

Specialised astrocytes

Answer 22

1.) rADIA

Question 23

Specialised astrocytes

Answer 23

1. ) Radial glia: in brain development
2. ) Bergmann glia (cerebellum)
3. ) Muller cells (retina)

Question 24

MND spinal cord shows pathological changes in

Answer 24

Motor neurons/microglia/astrocytes

Question 25

What does pathological CNS lesions in MS involve

Answer 25

Oligodendrocytes/neurons/T lymphocytes

Question 26

What does acute symptoms in MS reflect dysfunction in

Answer 26

neurons

Question 27

CNS terminology

Answer 27

- Abundance of neuronal cell bodies in nuclei - Axons gathered into tracts - Tracts that cross midline = commissures - Grey matter abundant in neural cell bodies & processes – neuropil contains few cell bodies White matter contains abundance of myelinated tracts & commissures

Question 28

PNS terminology

Answer 28

Cell bodies & supporting cells located in ganglia – e.g. dorsal root ganglia (DRGs) Axons bundled into nerves Many PNS axons are enveloped by Schwann cells (myelinating cellsof the PNS – neural crestderived)

Question 29

Blood brain barrier

Answer 29

- blue dyes in blood won't penetrate brain tissue

Question 30

How is the blood brain barrier formed?

Answer 30

Formed by endothelial cells/astrocytes and pericytes

Question 31

Features of the blood brain barrier

Answer 31

- Endothelial tight junctions - Astrocyte end feet - Pericytes - Continuous basement membranes: lacks fenestrations - Need specific transporters for glucose/water

Question 32

What do circumventricular organs lack

Answer 32

Normal BBB: sensory and endocrine functions

Question 33

What are these circumventricular organs

Answer 33

1. ) Subfornical organ 2. ) Pineal body 2. ) Area Postrema 3. ) Posterior Pituitary 4. ) Organum Vasculum of the Lamina terminalis

Question 34

CSF drainage

Answer 34

- occurs via multiple roots | - perineural route via olfactory/brainstem/spinal nerves

Question 35

Features of ependymal cells

Answer 35

- epithelial like - line ventricles + central canal of spinal cord - involved in CSF flow - Ciliated to facilitate flow - Allow solute exchange between vervous tissue and CSF

Question 36

Features of the choroid plexus

Answer 36

- formed from modified ependymal cells: villi form around network of capillaries- large surface area - Main site CSF production by plasma filtration - GAP junctions between cells form blood-CSF barrier - Projections in ventricles