Neurocytology

Question 1

Macroglia

Answer 1

1. astroglia
2. oligodendrocytes
3. oligodendrocyte precursor cells (NG2 cells)
4. ependymal cells

Question 2

From which germ layer did microglia originate from?

Answer 2

mesoderm

Question 3

gray matter

Answer 3

neuronal cell bodies and glia

Question 4

white matter

Answer 4

myelin-ensheathed axons

lipids

Question 5

hemotoxylin/eosin staining

Answer 5

nucleus/cytoplasm

Question 6

Nissl staining

Answer 6

nucleus
RER
RNA granules

Question 7

unipolar vs. bipolar vs. multipolar neurons

Answer 7

unipolar –> sensory neurons
bipolar –> interneurons
multipolar –> motor neurons

Question 8

motor neuron

Answer 8

single axon

multiple dendrites

Question 9

pyramidal neuron

Answer 9

single axon
basal dendrites (directly off soma) 
apical dendrites (br. off of a branch from soma, even more br. after)

Question 10

purkinje neuron

Answer 10

huge dendrite tree to receive massive amounts of inputs

Question 11

peripheral glia cells

Answer 11

Schwann cells (prod. myelin)
^ neural crest derived

Question 12

fast rate of conduction

large/small axon?
(thick/thin myelin sheath?)
(long/short distance between nodes of Ranvier?)

Answer 12

LARGER axon
THICKER myelin sheath
LONGER distance between nodes

–> FASTER rate of conduction

Question 13

what determines the potential input that a neuron can receive/controls synapse strength?

Answer 13

number/shape of dendrites and dendritic spines

Question 14

types of synaptic contacts

Answer 14

axodendritic synapse
axosomatic synapse
axoaxonic synapse

Question 15

conserved properties of in vivo mature grey matter astroglia

Answer 15

NON-electrically excitable, very low input-resistance

homeostatic function –> uptake glutamate through excitatory amino acid transporters (EAATs)

highly ramified cellular processes

extensive intercellular coupling though gap-junctions

Question 16

tripartite synapse

Answer 16

synapse has an astrocyte component

astrocytes respond to synaptic signals w/ Ca++ excitability –> slower

Question 17

astrocyte functions in CNS

Answer 17

1. metabolic support (support nutrients)
2. structural support
3. homeostatic functions
   - NT removal (glutamate)
   - K+ regulation in extracellular spaces
4. glymphatic system
5. synaptic modulation (secrete active transmitters)
6. synapse formation modulation (secrete extracellular matrix proteins –> synaptogenesis)

Question 18

glutamate-glutamine cycle

Answer 18

when glutamate is released –> excites neurons

excess glutamate –> picked up by glial cells (EAAT) –> conversion to glutamine –> transported back to neurons

key point=neurons don’t need to replenish glutamate every time

Question 19

Why can’t axons regenerate?

Answer 19

injury causes astrocytes to become GFAP+ and form glial scars –> axons can’t reconnect

Question 20

How are certain reactive astroglia toxic?

Answer 20

Some can secrete toxic factors that induce neuronal cell death.

Question 21

astrocytoma

Answer 21

major source of brain glioma

Question 22

key functions of microglia

Answer 22

surveillance

cluster around amyloid plaques

become active to release cytokines + carry out PHAGOCYTIC activities

high motility

Question 23

glial specific genes that predispose general population to Alzehimer’s disease

Answer 23

APOE

TREM2

Question 24

genes that cause Alzehimer’s disease but are VERY RARE in general population

Answer 24

PSEN

APP

Question 25

key functions of oligodendrocytes

Answer 25

myelin formation in CNS

*prevents leakage of current, maintains conduction velocity of AP

Question 26

key functions of Schwann cells

Answer 26

myelin formation in PNS
(basically a peripheral oligodendrocyte)

*prevents leakage of current, maintains conduction velocity of AP

Question 27

glial cells vs. neurons

total amounts in whole brain?

Answer 27

Glial cells are roughly equal to number of neurons comprising CNS.

Ratio varies in dif brain regions.

Question 28

Ependymal cells

Answer 28

type of glialcell.

line the CSF-filled ventricles in the brain and the central canal of the spinal cord

Question 29

Tanycytes

Answer 29

special ependymal cells found in the third ventricle of the brain, and on the floor of the fourth ventricle and have processes extending deep into the hypothalamus. It is possible that their function is to transfer chemical signals from the cerebrospinal fluid to the central nervous system.