Lecture 2: Neurons and Glia

Question 1

Neurons….

are post-_____

derive from the _____

have what components?

make ______

Answer 1

Neurons…

are post-mitotic

derive from the ectoderm

have soma, dendrites, and axons

make synapses

Question 2

Who came up with the Neuron Doctrine?

Answer 2

Cajal

Question 3

Neurons communicate with ______

Information flows from the _____ to the ____

Answer 3

Neurons communicate with directionality

Information flows from the soma and dendrites to the axon and synaptic terminals.

Question 4

Directionality:

MOST information travels from ____

BUT retrograde transport can occur where

• Post synaptic element can release _____ that can affect the presynaptic neuron

Explain examples of retrograde axonal transport

Answer 4

Most information travels from presynaptic neuron to post

BUT retrograde axonal transport can occur: post-synaptic elements can release trophic factors that can affect the presynpatic neuron

Examples:
muscles can send trophic factors to motorneurons

Varicella Zoster (chicken pox)

Poliovirus

Question 5

What are the “main effectors” of the nervous system?

Answer 5

The main effectors of the nervous system are neurons

Question 6

What are “glia”?

And how many of them are there compared to neurons?

Answer 6

Glia are non-neuronal cells within the nervous system

They contribute to development, structure. and provide the correct enviornmental factors and help repair neurons.

There are 10 x more glia than neurons

Question 7

Explain the difference between Microglia and Macroglia.

Answer 7

Microglia: small glia, they only function during damage and disease

NOTE: you will only see microglia functioning in damaged or diseased tissue

Macroglia: large glia… 80-90% of all glia

Question 8

What are the three main types of macroglia and what are their basic functions?

Answer 8

Macroglia:

1. Schwann cells (myelinate peripheral axons)
2. Oligodendrocytes (myelinate the CNS axons)
3. Astrocytes (do a lot of things, help with cytotoxicity)

Question 9

What is the innate immune system of the CNS?

Answer 9

Microglia

Question 10

What are microglia?

Where are microglia found?

When are they reactive?

Answer 10

Microglia are the “innate immune system” of the CNS

They are tissue macrophages that populate the CNS during early embryonic development

They are found in all regions of the brain and spinal cord (CNS)

They become reactive during disease (HIV, Alzhiemer’s, parkinson’s)

Evidence shows they can be neuroprotective and neurotoxic at different stages of disease

Question 11

Astrocytes make close contact with _______

Answer 11

Astrocytes make close contact with SYNAPTIC TERMINALS

Question 12

Astrocytes influence the synaptic response by releasing ______

Answer 12

Astrocytes influence the synaptic response by releasing Glutamate

Glial glutamate release can influence neighboring neurons

Remember, astrocutes are close to synaptic cleft

Question 13

Explain how neuronal activity can induce calcium signaling in astrocytes

Answer 13

Astrocytes are electrically coupled and connected via connexons

Ca signaling spreads between astrocytes, forming calcium waves

This occurs via IP3 diffusion via connexons

Longer range diffusion requires ATP

Question 14

How many types of oligodendrocytes are there?

Answer 14

Four Types of Oligo’s

1. Can integrate many levels
2. Only acts horizontally
3. goes between two layers
4. looks a lot like schwann cells

Question 15

Neurons get glucose out of the blood because they cannot make it themselves

What kind of glia transports the nutrients such as lactate to neurons of the CNS?

Answer 15

Oligos transport lactate to axons

Question 16

________ modulate synaptic transmission

Answer 16

Schwann Cells modulate synaptic transmission

Perisynaptic Schwann Cells can modify the post synaptic response at the NMJ (PSCs do not myelinate, they only modulate activity)

Schwann cells have direct control of synaptic activity

Question 17

What kind of Schwann cells do not function as myelinating agents but rather modulate synaptic activity?

Answer 17

Perisynaptic Schwann cells can modify the post-synaptic response at the NMJ

PSCs are non-myelinating

Question 18

Communication between nodal glia and axons at the nodes of Ranvier is essential:

• ________ glia maintain proper axonal function at the nodes of Ranvier
• They dictate ____

Answer 18

Paranodal glia maintain proper axonal function at the nodes of Ranvier

They dictate the molecular organization at the axon for normal function; this is lost in demyelinating disease

Question 19

What kind of cells provide a type of anchor at the nodes of Ranvier for ion channels and other important things?

Answer 19

Paranodal glia

They express proteins to anchor and attract ion channels at the ndoes of ranvier

Question 20

Most brain tumors are neoplasms of ___ cells

Answer 20

Most brain tumors are neoplasms of glial cells

(glioblastomas, schwannomas, astrocytomas)

Question 21

What is the most severe kind of brain tumor?

Answer 21

Most severe brain tumor is glioblastoma multiforme

death occurs within a year of diagnosis

Question 22

What is the most abundant type of brain tumor?

Answer 22

Meningiomas are the most abundant type of brain tumor
They are tumors of non-glial cells (arachnoid) or pituitary adenomas

Question 23

What kind of tumor is a pituitary adenoma and what does it look like?

Answer 23

Pituitary adenoma is a type of meningioma

Question 24

Schwannomas occur _________

Also called _____

Answer 24

Schwannomas occur at the root of the cranial nerve innervating the inner ear: “acoustic neuromas”

They are relatively common and treatable

Question 25

______ tumors are usually benign because they do not metastasize, but they can be dangerous if they _____

Answer 25

Intracranial tumors are usually benign because they do not metastasize, but they can be dangerous if they increase intracranial pressure

Question 26

Define what paraneoplastic diseases are

Give two examples

Answer 26

Paraneoplastic diseases arise from tumors elsewhere in the body that release substances that affect the nervous system

Examples:

Cushing syndrome and Lambert Eaton Syndrome

Question 27

Explain Cushing’s syndrome and Lambert-Eaton Syndrome

Answer 27

Both are “paraneoplastic diseases” which are tumors that affect the nervous system but originate elsewhere in the body

Cushing’s syndrome: secondary to cell lung carcinoma, emits adrenocortiocopic hormones, cause upper body obesity, excess hair growth, HTN, increased thirst and urination

Lambert-Eaton Syndrome: small cell lung carcinoma produces autoantibodies against neuronal proteins that impair synaptic transmission mostly of the motor neurons and skeletal muscle