Foundation - Microanatomy

Question 1

What are the nervous system’s functional units

Answer 1

Nerve cells (neurons)
Glia cells (neuroglia)

Question 2

Neurons

Answer 2

basic unit of the nervous system, involved in the
acquisition,
integration,
and transmission of electrical signals

Unique morphology

Question 3

Neuroglia

Answer 3

homeostasis-maintaining cells that support neurons and allow them to function optimally by performing a variety of functions

Question 4

Basic structure of neurons

Answer 4

Core region called soma (or cell body)
Branching extensions that collect information named dendrites
One root that transmit messages named axon

have ONLY one axon, but can have many dendrites

Question 5

How neurons orient themselves in space and time

Answer 5

they are highly polarized

Question 6

Flow of information on a neuron

Answer 6

is unidirectional

Dendrite → Soma → Axon → Synapse → Dendrite

Question 7

Types of synapses

Answer 7

1. Axon terminal-dendrite
2. Axon terminal-spine (1)
3. Axon terminal-soma (2)
4. Axon – Axon

Question 8

Synaptic cleft is too large for

Answer 8

ionic changes
→ neurotransmitters

Question 9

Types of Receiving receptors

Answer 9

Ionotropic - let ions pass in response to neurotransmitter binding. (are ion channels themselves)

metabotropic - require other signaling cascades to connect neurotransmitter binding to ionic activity in neurons. (do not have an ion channel and instead connect to an ion channels through one or more signaling cascade pathways.)

Question 10

Ways to classify neurons

Answer 10

1) morphology
2) type of info processing

Question 11

Neuron Morphology

Answer 11

(based on number and placement of
extensions out of the soma)

1. Unipolar
2. Bipolar
3. Multipolar
4. Pseudounipolar

Question 12

Neuron Role

Answer 12

(based on the type of information they process)
1. Sensory - to CNS
2. Interneuron - In CNS
3. Motor - out of CNS

Question 13

How neuron micro-structure determines macro-anatomy

Answer 13

Question 14

Types of (CNS) neuroglia

Answer 14

• Astrocytes (1st evolutionary)
• Oligodendrocytes (mylen)
• Microglia (resident immune - OJ from blood)
• Ependymal cells

Others: specialized or ill-defined glia
* NG2 cells
* Radial glia
* Müller glia
* Bergmann glia

Question 15

astrocytes

+ functions

Answer 15

Issues with - result in severe disease

Star shaped, most abundant glia cell

functions:
1. Regulates neuronal communication
(synaptogenesis)
2. Regulates blood-brain barrier (BBB)
3. Nutrients support to neurons
4. Regulates signal transmission by interacting with
nodes of Ranvier (space between myelin sheets)
5. Repair metabolic damage (ROS; osmotic; pH)

Question 16

Oligodendrocytes

Answer 16

Cells in charge of myelination in CNS (similar to Schwann cells in PNS)

• They surround axons and produce myelin
• Are the most proliferative cells of the CNS

Question 17

NG2 cells

Answer 17

act as multipotent precursors to other glia, in particular oligodendrocytes

• can generate olig.
• like stem cells
• important in MS - why MS is like episodes - no more episodes - no more NG2

Question 18

Mylen

Answer 18

olig produces many proteins - mylen is one

increseas speed of signal - can “jump” with mylen

Question 19

microglia

+ functions

Answer 19

Originates in the blood - Enter the CNS during embryonic development + never leave

Very long-lived (varies between brain regions)

Main immune cell of the CNS - “Resident macrophages”

Functions:
Travel throughout the brain and spinal cord (1)
* Keep it clean!
* Synaptic pruning (2)
* Removal of death cells (3)
* Remodeling of neuronal networks (4)

Question 20

ependymal cells

Answer 20

ARE Epithelial cells
- found in the walls of the ventricles

Make and secrete cerebrospinal fluid (CSF)
-Ciliated, create flow of CSF

Question 21

Evolutionary, as the brain size increases the

Answer 21

ratio of glia : neuron increases as well
- varies greatly from region to region in the brain