3 – Neuro Histology Part I

Question 1

Cell types of CNS:

Answer 1

-neurons
-glia
-microglia
-endothelial

Question 2

Glia in CNS:

Answer 2

-oligodendrocytes
-astrocytes
-ependyma
*all derived from neural tube (neural SC)

Question 3

Microglia:

Answer 3

-macrophages recruited to CNS
-from mesoderm

Question 4

Endothelial cells:

Answer 4

-invading CNS to nourish
*important for making BBB
-from mesoderm

Question 5

Cell types of PNS:

Answer 5

-sensory and motor neurons
-Schwann cells
-pericytes (support, role in BBB)

Question 6

Tissues of CNS:

Answer 6

-white matter vs. grey matter
-meninges

Question 7

White matter:

Answer 7

-myelinated axons
>makes it look white due to fat
-glia

Question 8

Grey matter:

Answer 8

-cell bodies
-some glia

Question 9

Meninges:

Answer 9

-cover the entire CNS
-3 layers of connective tissue
>from invading fibroblasts from mesoderm
-not in PNS

Question 10

3 layers of meninges: outside to inside

Answer 10

-dura mater: tough
-arachnoid mater: web-like structure
-pia mater: adhered to brain tissue

Question 11

Neurons:

Answer 11

-functional units of NS
>form synapses with other cells (neurons or target organs)
-lots of them! (billions)
>more in sophisticated animals (ex. humans)
-supported by glia
*way more glia then neurons

Question 12

Neurons structure:

Answer 12

-cell body (soma)
-dendrites (where neurons synapse)
-axon
-terminal branches
-telodendrites (synapse with next neuron)
*unidirectional signalling

Question 13

Function of neurons:

Answer 13

-signal transmission from PNS to CNS to allow animal to respond to environmental changes

Question 14

Neurons in CNS:

Answer 14

-responsible to integrating and interpreting

Question 15

Neurons in PNS:

Answer 15

-responsible to detection and performing response

Question 16

Neurophil:

Answer 16

-represents space between neurons and glia
>dendritic processes and synapses

Question 17

CNS histology:

Answer 17

-VERY tightly packed (no intracellular space)
-no connective tissue IN the CNS
>connective tissue arises from mesoderm (fibroblasts)

Question 18

Synapse example: NMJ

Answer 18

-neuromuscular junction in PNS
>single axon can innervate muscle fibers
>*individual muscle fibers are ONLY innervated by ONE axon

Question 19

PNS synapses:

Answer 19

-1 NT
-only input from one neuron
-effect of NT is defined

Question 20

1 NT of PNS:

Answer 20

-ACh
>always excitatory

Question 21

Effect of NT is defined in PNS:

Answer 21

-AP always initiates depolarization and target organ response

Question 22

CNS synapses:

Answer 22

-many NTs
-each neuron receives 1000+ synapses
-effect of NT can be varied
-synapses can influence MP but also participate in neuromodulation

Question 23

Many NTs of CNS:

Answer 23

-gaba (negative)
-glutamate (positive)

Question 24

Effect of NT can be varied:

Answer 24

-single AP input only changes MP a small amount
*need multiple inputs to depolarize cell and initiate action (summation effect)

Question 25

Synapses of CNS can participate in neuromodulation:

Answer 25

-phosphorylation of proteins
-second messenger activations
-activate of transcription/translation