Basic Review (Unique Brain and Histology)

Question 1

How is the brain unique in response to injury?

Answer 1

Glial cells form scars, not fibroblasts.

Question 2

Does the brain have lymphoid drainage?

Answer 2

No, it has CSF system instead.

Question 3

4 Types of Glial Cells

Answer 3

Astrocytes, oligodendrocytes, ependymal cells, microglia

Question 4

Astrocytes

Answer 4

Make up 20-50% of brain volume. Provide structural framework for CNS, metabolic support, maintain ion balance, SUPPLIES GLUTAMATE TO NEURONS, ectodermal origin.

Question 5

Oligodentrocytes

Answer 5

Myelinate neurons in the CNS, ectodermal in origin

Question 6

Microglia

Answer 6

MESODERMAL in origin, resident macrophages, no known function in resting state but make cytokines and neurotoxins that mediate neuronal inflammation and kill damaged neurons

Question 7

What parts of the CNS are most sensitive to anoxia?

Answer 7

Soma > axon > myelin > oligodentrocytes > astrocytes > microglia > blood vessels

Question 8

Most sensitive brain regions to anoxia or glucose deprivation

Answer 8

Cortical layers 3 and 5, hippocampal neurons (CA1), purkinje cells

Question 9

Eosinophilic degeneration

Answer 9

Cytoplasm becomes eosinophilic and nucleus becomes pyknotic after injury. Happens 4-6 hours after injury and is irreversible.

Question 10

Axonal Reaction to injury

Answer 10

Reversible if the integrity of the exon is restored, but otherwise, the soma swells and rounds, nissl substance (RER) disappears, nucleus moves to the side.

Question 11

3 Steps of Glial Scar formation

Answer 11

1) Astrocytes proliferate
2) Astrocytes become reactive (cytoplasm swells, processes extend)
3) Glial scar deposited made of Glial Fibrillary Acidic Protein (GFAP).

Question 12

Vasogenic edema

Answer 12

Failure of BBB astrocytes and endothelial junctions. Allows normally intravascular fluid to penetrate into the cerebral parenchyma. Responsive to steroids and osmotic therapy and frequently seen with tumors/abscesses/trauma.

Question 13

How to treat vasogenic edema?

Answer 13

Steroids and osmotic therapy (mannitol –diuretic)

Question 14

Cytotoxic Edema

Answer 14

BBB intact, but hypoxia/ischemia/overdose damages endothelial cells and astrocytic processes. Causes failure of ion pumps, retention of sodium, water rushes in, cell swells. Does not respond to steroids/diuretics

Question 15

How to treat cytotoxic edema?

Answer 15

Does not respond to steroids/osmotics.

Question 16

Symptoms of increased intracranial pressure:

Answer 16

Headache, nausea, vomiting, bradycardia, LOC.

Question 17

Monroe-Kellie Doctrine

Answer 17

Skull has a fixed volume that is normally filled by brain matter, CSF, and blood in the correct volumes. However, when the volume of one of these three things increases, the volume of the other two must decrease. If they don’t an increase in intracranial pressure will occur.

Question 18

Cerebral Perfusion Pressure

Answer 18

MAP-ICP = CPP

Question 19

Two places of neuronal generation?

Answer 19

Hippocampus and SVZ (lateral ventricles).

Question 20

Ependymal Cells

Answer 20

Line ventricles

Question 21

Multipolar Neuron

Answer 21

Many dendrites surround soma, long axon

Question 22

Bipolar Neuron

Answer 22

Cell body integrated into middle of cell, dendrites and axon on either side of projection. CN VIII and retina.

Question 23

Unipolar Neuron

Answer 23

Cell body is a separate process (looks like a bud). Sensory neurons.

Question 24

Amacrine Cells

Answer 24

No axon at all, found in retina

Question 25

Histologic characteristic of spinal cord motor neurons

Answer 25

Nissl Substance

Question 26

Where are schwannomas common?

Answer 26

At the point of entry of CN VIII to brainstem

Question 27

Important differences between the meninges of spinal cord and cerebrum

Answer 27

Cerebrum has 2 layers of dura and only 1 pial layer. Cerebral blood vessels lie on the surface of the intima pia (as opposed to epipia). Arachnoid villi are much more common in cerebellum.

Question 28

Bones of the cranium

Answer 28

Frontal, parietal (2), temporal (2), occipital, sphenoid, ethmoid.

Question 29

Three main compartments of base of skull

Answer 29

Anterior, Middle, posterior fossa.

Question 30

CSF Cisterns

Answer 30

Quadrigeminal cistern, interpeduncular cistern, pontine cistern, cisterna magna, lumbar cistern.