CNS Histology Dennis T#2

Question 1

Describe the typical neruon structure.

Answer 1

Cell body with a large nucleus and nucleolus and nissl bodies. Numerous dendrites extend off of the cell body and one axon from the axon hillock

Question 2

Describe the presynaptic terminal bouton.

Answer 2

Contains mitochondria and synaptic vvesicles and they release NT via exocytosis

Question 3

What is a multipolar neuron?

Answer 3

Neuron that has multiple dendrites and one axon with multiple branches, target can be muscle cells or other organs

Question 4

Bipolar neuron

Answer 4

Centrally positioned ccell body with two processes on each side. One is a dendrite and the other is an axon. Found in the retina

Question 5

Unipolar neuron?

Answer 5

Found in dorsal root ganglion and dedicated to sensory function. One cell body and one short process that extends and branches into one short and long process. Shorter is positioned centrally within the nervous system and relays info into spinal cord and the longer one goes to target for example skin.

Question 6

Anoxonic neuron?

Answer 6

Single cell body with multiple dendrites but no axon to communicate through AP just processing information from the dendrites. It is not very common.

Question 7

What is synaptic communication?

Answer 7

Unidirectional communication that converts an electric signal to a chemical signal via neurotransmitters.

Question 8

Describe the chemical synapse.

Answer 8

The presynaptic terminal bouton contains mitochondria and synaptic vesicles to be released via exocytosis. They diffuse acorss the cleft to bind on the postsynaptic cell membrane which contains GPCRs or ion channels to cause movement of ions to stimulate or inhibit signal.

Question 9

What is the electrical synaps

Answer 9

Direct passive flow of electrical currents between neurons through gap junctions. Gap junctions are made of connexon proteins which link the pre and post synaptic membranes. These are found in cardiac muslce.

Far less common in CNS

Question 10

What is the hallmark marker to identify astrocytes?

Answer 10

Glial fibrillary acid protein GFAP

Question 11

What do astrocytes do?

Answer 11

Form a network of delicate terminals contacting synapses and other structures. They use perivascular feet to create BBB to block pores on capillary beds.

Question 12

Choroid plexus structure, location, and function.

Answer 12

Columnar or cboidal cells that line the ventricles and central canal of spinal cord. The apical end has cilia and long microvili that facilitate the movement of CSF and involved in absorption. They do NOT have a basal lamina.

Question 13

ID

Answer 13

4th ventricle with ependymal cells making up the choroid plexus

Question 14

ID and function

Answer 14

• MIcroglia- elongated nuclei
• Derived from monocytes
• Immune defense in the CNS
  
  • remove damaged or unactive synapses or cellular debris

Question 15

ID and function

Answer 15

• Contact multiple axons and wrap axons in myelin.
• Multiple oligodendrocytes can enwrap the same axon.
• Usually small cells with round condensed nuclei and unstained cytoplasm

Question 16

What are the two types of peripheral glia?

Answer 16

• Neurolemmoytes aka schwann cells:
  
  • myelinate peripheral nerves
  • only one cell wraps one segment of an axon
• Satellite cells:
  
  • found in DRG and provides structural and metabolics support for neuronal cell bodies

Question 17

What are the six layers of the cerebral cortex?

Answer 17

1. Molecular: fibers and neuroglial cells
2. External granular layer
3. External pyrimidal layer
4. Inner granular layer
5. Ganglionic layer: extra large pyrimidal cells especially in the motor areas
6. Multiform polymorphic layer: cells with diverse shapes

Goes youngest to oldest from superficial to deep

Question 18

What is the most common neurodegenerative disease?

Answer 18

Alzheimer’s Disease

• Amyloid Beta plaques amorphous pink masses in the cortex stained with HE
• Neurofibirillay tangles have accumulation of protein tau, flame shaped skeins formed

Question 19

What disease is present?

Answer 19

alzheimers

Question 20

What is the significace of substantia nigra?

Answer 20

• Connections with the cortex, spinal cord, corpus striatum and retiular formation and directly involved in motor function.
• It contains dopamine within the neuromelanin which will inhibit movements

Question 21

What is being compared?

Answer 21

Brain stem with substantia nigra. Right section has adaquate substantia nigra and the individual on the left is lacking neuromelanin pigment so they had a decrease in dopamine resulting in parkinsons.

Question 22

What is seen and in what conditions is this seen

Answer 22

Lewy body is seen in the remaining neurons composed of aggregates of alpha synyclein. The halo around the body is hallmark.

Parkinsons disease

Question 23

Describe the cereballar cortex

Know how to identify histology and what is in each layer

Answer 23

1. Molecular: scattered neuronal cell bodies, contains basket cells
2. Purkinjie: dendrites extend throughout the moolecular layer, seen in a row speckeled throughout
3. Granular: deepest layer of cells and contains small dense packed granular cells and little neurophil. White matter (medulla) is below

Question 24

What is the dense staining purple?

Answer 24

Granular layer of cereballar cortex containing dense packed neurons and littlel neurophil

Question 25

outlined section?

Answer 25

Purkinjie layer of the cerebellar cortex

Question 26

What are the arrows pointing to?

Answer 26

Anterior horns with large motor neuron bodies

Question 27

ID the dots