CNS Histo

Question 1

What’s in a cell body or soma

Answer 1

Well-developed nucleus and Nissl substance/bodies. The cell body stains darkly because of high ribosomal activity in Nissl substance.

Question 2

Where do the dendrites extend from and what do they do

Answer 2

Extend from the perikaryon. Sense info. Increase receptive SA. Spines are plastic

Question 3

What is the neuropil

Answer 3

Dense network of nerve fibers and their branches & synapses together w/ glial filaments

Question 4

Anterograde transport

Answer 4

Carry material from nerve cell body to axon

Uses kinesin, a microtubule associated motor protein

Question 5

Retrograde transport. Which illness associated w/ this?

Answer 5

Carry material from axon terminal to cell body or dendrites to cell body
Uses dynein, a microtubule associated protein

How you get shingles

Question 6

Which elements use slow transport

Answer 6

Cytoskeletal elements. Move at 0.2-4 mm/day.

Question 7

Which elements use fast transport

Answer 7

Endocytosed toxins and viruses. 20-400 mm/day

Question 8

Describe synaptic communication

Answer 8

Nerve impulses transmitted from one enuron to effector cells unidirectionally.

Converts electrical signal from presyn cell to chemical signal that affects postsyn cell.

Most act by NT release

Question 9

What’s on the post syn cell membrane

Answer 9

Receptors for the NT. Ion channels to initiate a new impulse.

Question 10

What types of synapses are there?

Answer 10

Axosomatic, axodendritic, and axoaxonic. Allows dor signal modulation when signals come in at the same time. Lets neurons decide how to act.

Question 11

How do electrical synapses work?

Answer 11

Use gap junctions for direct PASSIVE flow of electrical current between neurons. Connexon links the pre and post synaptic membranes to help with ion movement.

Question 12

What do astrocytes do?

Answer 12

• Perivascular feet surround cerebral vasculature to help form BBB.
• Form network of synapses
• Help with NT reuptake so cells dont become overresponsive
• Regulate ion concentration
• Replicates to occupy space of dying neurons

Question 13

What protein helps reinforce the proximal regions of astrocytes?

Answer 13

glial fibrillary acid protein (GFAP)

Question 14

What do oligodendrocytes do? How do they appear?

Answer 14

Form myelin sheath in CNS. Enwrap axons from multiple neurons. Allows faster AP propagation along CNS axons.

Small cells with rounded, condensed nuclei and unstained cytoplasm.

Question 15

What do ependymal cells do?

Answer 15

Facilitate movement of CSF
Likely involved in absorption
Joined apically by apical junctional complex to create fluid boundary.

Question 16

How do ependymal cells appear?

Answer 16

Columnar/cuboidal cells lining the brain ventricles and the central canal of spinal cord. Apical end may have cilia and long microvilli. No basal lamina.

Question 17

Where is the choroid plexus found and what is it made of?

Answer 17

Found in roof of 3rd and 4th ventricle and parts of lateral ventricular walls.

Combo structure of ependymal cells and pia vasculature.

Question 18

What helps to prevent leakiness in relation to CSF?

Answer 18

Tight junctions (zonula ocludens) between epithelial cells.

Question 19

How do the blood vessels in choroid plexus run?

Answer 19

Run in fronds composed of fibrous core covered by cuboidal/columnar epithelium.

Question 20

What do microglia do? Where do they originate from?

Answer 20

Behave like macrophages and remove damaged or inactive synapses or other fibrous components. Remove microbial invaders. Originate from monocytes.

Question 21

Where is the central canal and what lines it?

Answer 21

Central canal lies in the central commisure of grey matter and is lined by ependymal cells and contains CSF. Extends length of spinal cord.

Question 22

What is in the anterior and posterior horns?

Answer 22

Anterior: Large motor neurons that feed out as efferent output.

Posterior: Incoming sensory delivered via axon.

Question 23

What does white matter in spinal cord consist of?

Answer 23

Ascending tracts of sensory fibers and descending tracts of motor tracts.

Question 24

3 layers of the cerebellar cortex

Answer 24

1. Molecular: lots of neuropil
2. Purkinje: extending dendrites w/ prominent cell bodies
3. Granular: little neuropil, densely packed neurons

Question 25

Cell types of the neocortex? There are 5.

Answer 25

1. Pyramidal cells: multipolar neurons
2. Granule cells: cell body shaped like a star
3. Cells of martinotti: small cells w/ short dendrites
4. Fusiform cells: angled at right angles to surface of cerebral cortex
5. Horizontal cells of Cajal: oriented parallel to surface.

Question 26

What are the 6 layers of the cortex?

Answer 26

1. Molecular - mostly neuroglial cells and cajal cells
2. External granular
3. External pyramidal
4. Inner granular
5. Ganglionic - large pyramidal cells in motor areas
6. Multiform - closest to white matter at bottom

Question 27

Histo findings of Alzheimers

Answer 27

• Thinning gyri in temporal and frontal lobes
• Amyloid plaques: amorphous, pink mass in cortex
• Neurofibrillary tangles: flame-shaped skeins formed by tau buildup

Question 28

Importance of neuromelanin pigment

Answer 28

Located in the substantia nigra.

This pigment contains dopamine which has INHIBITORY effects in brain areas dedicated to movement.

Loss of this pigment due to substantia nigra degeneration leads to loss of movement inhibition or Parkinsonism.

Question 29

What are Lewy bodies and what are the made of?

Answer 29

When the substantia nigra degenerates, we sometimes have “left over” neurons. They form distinctive inclusions called Lewy bodies. Made of alpha-synuclein aggregate.