Section 2 - Cell Biology of Neurons and Glial Cells

Question 1

_____ injection follows neurons retrogradely (back to cell body)

Answer 1

HRP (horseradish peroxidase) (which is, i’m sure, carly’s favorite peroxidase)

Question 2

Lipophilic dyes: ____ label postsynaptic neurons ____ label presynaptic neurons

Answer 2

DiO DiI (stain living or dead)

Question 3

_____ travel anterogradely; can cross synapses to label distribution patterns of neurons

Answer 3

Radioactive amino acids

Question 4

_____ virus transports retrogradely and then _____ adjacent cells, go to CNS; eventually go anterograde to _____

Answer 4

Rabies virus; produces and sheds copies of virus to; salivary glands

Question 5

_____ is transported retrogradely from axon terminals at site of infection. What is a big difference from rabies?

Answer 5

Tetanus toxin (from clostridium tetani). It is a bacteria and is DILUTED cell-to-cell (no replication).

Question 6

What is the supposed pathology of bipolar disorder?

Answer 6

Imbalances in phosphatidyl inositol (PI) (which is linked to neurotransmitters acetylcholine, serotonin, norepinephrine, histamine)–> mood changes

Question 7

How do we treat bipolar disorder?

Answer 7

Drug: lithium carbonate (stabilizes PI turnover and stabilizes mood)

Question 8

What is the pathology of Alzheimer’s disease?

Answer 8

Degeneration of neurons in basal forebrain nuclei, loss of synapses in cerebral cortex and hippocampus, presence of neurofibrillary tangles and senile plaques. Cortical cells lose cholinergic terminals and choline acteyltransferase levels in cortex/hippocampus are VERY LOW.

Question 9

What is myasthenia gravis?

Answer 9

Patient’s immune system produces antibodies to nicotinic acetylcholine receptors –> destruction of neuromuscular junctions

Question 10

What is an astrocytic scar?

Answer 10

Destruction of cells in CNS due to injury creates space filled with proliferation/hypertrophy of astrocytes (they retain ability to divide in the brain, so they are very common for CNS tumor)

Question 11

Astrocytic tumors are most often in _____

Answer 11

the frontal and temporal lobes

Question 12

What mediates the CNS inflammatory response?

Answer 12

Cytokine, (IL)-1, tumor necrosis factor alpha, and prostaglandin release from microglia and astrocytes

Question 13

What is neurovascular coupling?

Answer 13

Blood flow increases to areas of increased neuronal activity

Question 14

What is functional hyperemia?

Answer 14

A consequence of neurovascular coupling (increase in blood to accommodate tissue activity). It is defective in conditions such as migraine, stroke, hypertension, spinal cord injury, and Alzheimer’s.

Question 15

What is spreading depression?

Answer 15

Wave of suppressed neuronal activity, spreading across regions of gray matter –> decreased blood flow that could damage neurons and lead to potential negative feedback (low oxygen leads to reduced NO, leads to further reduced oxygen). NO dilates vessels.

Question 16

What is multiple sclerosis (MS)?

Answer 16

Loss of myelin results in interrupted propagation of APs down axons. Remyelination is possible.

Question 17

What is this?

Answer 17

Dawson fingers are a radiographic feature depicting demyelinating plaques through the corpus callosum, arranged at right angles along medullary veins. Characteristic of MS.

Question 18

What is microglial withdrawal?

Answer 18

Microglia reshape processes to form long rod cells apposed to afferent neurons; can become motile (phagocytes) in tissue injury and migrate to site for phagocytosis. Happens in viral encephalitis, neurosyphilis, etc.

Question 19

How to microglia act following peripheral nerve damage?

Answer 19

Surround motor neuron cell bodies in brainstem, displace all synapses. Once targets are re-established, new synapses can form. This is synaptic stripping.

Question 20

Microglia can be harmful when they’re trying to help…how?

Answer 20

When phagocytosing bacteria, release IL-1B –> loosens tight junctions (allows leukocytes and plasma to enter CNS –> bacterial meningitis)

Question 21

What is an astrocytoma?

Answer 21

Glial tumors encountered most often.

Question 22

Describe a Grade 1 astrocytoma

Answer 22

Resemble differentiated astrocytes reacting to injury, growing slowly, gradually enlarging

Question 23

Describe Grade 2 astrocytoma

Answer 23

Prominent processes filled with glial filaments, recur afer surgery where they may become more aggressive (become higher grade). They are vengeful little bastards.

Question 24

Describe Grade 3 astrocytoma

Answer 24

Nuclei that are enlarged with increasing chromatin density, nuclear uniformity lost, blood vessel density increased and growith is rapid. Malignant.

Question 25

Describe Grade 4 astrocytoma

Answer 25

Glioblastoma multiforme.

HIGHLY MALIGNANT. Astrocytes spindled, elongated, mitotic figures present. Invade leptomeninges, spread from continuos gyri, cross corpus callosum.

Question 26

What is an oligodendroglioma?

Answer 26

Slow growing tumor in brain lobes; dark, round nuclei with clear cytoplasm. Enlarged clusters around neurons and nodules of tumor cells beneath pia.

Question 27

Where are ependyomas located?

Answer 27

Spinal cord (cervical), any ventricle, spaces of posterior fossa. Not very aggressive and can be dissected away.

Question 28

Ependyomas can cause supratentorial lesions, leading to ______

Answer 28

hydrocephalus or seizures; nausea, vomiting, headaches, cranial nerve signs

Question 29

What differentiates ependyomas from choroid papillomas?

Answer 29

Presence of basal bodies.

Question 30

What is a microglioma?

Answer 30

Lymphoma of brain consisting of B and T cells.

Question 31

Child tumors are primarily ______

Answer 31

Medulloblastomas (retain embryonic unrestrained growth and rapidly spread along surface of brain and spinal cord)

Question 32

What are common benign primary tumors?

Answer 32

Meningiomas or schwannomas. Covered by fibrous vascularized capsule. Can compress normal tissue.

Question 33

How do prostate carcinomas tend to metastasize to the CNS?

Answer 33

To spinal cord via the Batson venous plexus

Question 34

Compare/contrast schwannomas and neurofibromas. (Tumors of PNS)

Answer 34

Schwannoma: encapsulated, no nerve fiber involvement, easitly excised

Neurofibroma: difficult to remove, unencapsulated, invade nerve fibers

Question 35

When is the best chance of recovery for axonal damage?

Answer 35

Crushed axon in PNS - focal demyelination expected to recover

Question 36

What is axonotmesis?

Answer 36

Compression of axon (proximal axon sprouts, distal Schwann stays, so regeneration can occur in the same position)

Question 37

What is neurotmesis?

Answer 37

Nerve is severed (regeneration less likely because it may not go to the right place)

Question 38

What is neurapraxia?

Answer 38

Nerve conduction failure (focal demyelination without axonal degeneration)

Question 39

What is the process that ends up causing “phantom pain”? (as in limb amputation)

Answer 39

Axons fail to enter Schwann cell tubes and can end blindly in connective tissue, form neuromas. Stimulation of these fibers leads to phantom pain.