Neurons and Glia

Question 1

Neurons are___ Continuous

Answer 1

Not

Question 2

Evidence for chemical transmission in a synapse

Answer 2

• Shows a delay in transmission, where if it was only electrical, it should have none
• Flow of information in a chain is unidirectional
• Transmission at synapses was found to be excitatory as well as inhibitory

Question 3

Soma

Answer 3

Cell body where metabolic processes of the cell occur.

Question 4

Axon

Answer 4

process that leaves the cell body (soma)

Question 5

Dendrite

Answer 5

term used to describe branches on which
incoming fibers (afferents) make connections (synapses).

Question 6

Spines

Answer 6

Thorn-like protrusions on dendrites; site of most synapses.

Question 7

Synapses

Answer 7

Receiving stations for excitation or inhibition.

Question 8

Unipolar Cell

Answer 8

only 1 neurite;
often seen in invertebrates/insects

Question 9

Bipolar Cell –

Answer 9

1 dendrite, 1 axon;
peripheral nervous system, e.g. retina

Question 10

Pseudo-unipolar Cell

Answer 10

no
dendrites, but an axon that splits into 2
branches (peripheral nervous
system/spinal cord)

Question 11

Multipolar Cells

Answer 11

– most common
in CNS; multiple dendrites, 1 axon

Question 12

GABAergic Interneurons are

Answer 12

(inhibitory neurons)

Question 13

Glia cells outnumber neurons by a ratio of

Answer 13

~ 3:1
ratios vary considerably by brain area

Question 14

5 Main Functions of Glial Cells

Answer 14

1. to surround neurons and hold them in place (→ Astrocytes)
2. to supply nutrients and oxygen to neurons (→ Astrocytes; Ependymal cells)
3. to insulate one neuron from another (→ Oligodendrocytes)
4. to destroy pathogens, and remove dead neurons (→ Microglia)
5. modulate neurotransmission by making more or less neurotransmitter-precursor available (Astrocytes)

Question 15

Role of Microglia

Answer 15

immune cells for the brain

Make up 10-15% of all cells in brain

Question 16

Microglia in their resting state…

Answer 16

move around and survey their domain for debris.

Question 17

After injury or inflammation, microglia…

AKA Alerted/Migratory AND Reactive/Fully Activated Microglia

Answer 17

are activated and they
migrate to the site of injury to
help clear dead and dying cells

debris

they phagocytose

Question 18

Microglia work with…

Answer 18

astrocytes to repair or isolate lesions in the nervous system

Question 19

Microglia can also produce small molecules called

Answer 19

cytokines that trigger
cells of the immune system to respond to the injury site.

Question 20

Microglia can be seen as a double edged sword because…

Answer 20

They can produce both neurotoxic (disturbs neuronal function; such as inflammatory cytokines) and neuroprotective factors

Question 21

Types of Macroglia

Answer 21

• Astrocytes
• oligodendrocytes / Schwann cells
• Ependymal cells

Question 22

Astrocytes make up…

Answer 22

~50% of all the cells in the brain

Question 23

Astrocytes can be classified into several subtypes based on

Answer 23

lineage (development), anatomy, or receptor/transporter
expression

Question 24

Four Functions of Astrocytes

Answer 24

• Structural
• Transmitter uptake and release
• Regulation of ion concentration
• Blood-brain barrier support

Also:
* Glycogen fuel reserve buffer
* Metabolic support: provide neurons with nutrients such as
lactate.
* Glucose sensing.
* Promotion of the myelinating activity of oligodendrocytes
* Nervous system repair

Question 25

Structural Functions of Astrocytes

Answer 25

* closely associated with neuronal synapses. * Regulate synaptic transmission

Question 26

Function of Astrocytes: Transmitter uptake and release

Answer 26

express plasma membrane transporters such as glutamate transporters for several neurotransmitters, including glutamate, ATP, and GABA. important for neurotransmitter synthesis and regulation of the metabolic activities of neurons. They take up and recycle GABA and glutamate that are released at synaptic clefts. They then release glutamine, which can be used by neurons to make new glutamate (excitatory) and/or GABA (inhibitory).

Question 27

Function of Astrocytes: Regulation of ion concentration

Answer 27

(esp. potassium) in the extracellular space

Question 28

Function of Astrocytes: Blood–brain barrier

Answer 28

with endothelial cells that form the blood-brain barrier that protects the brain. Astrocyte activity is linked to blood flow in the brain,

Question 29

Oligodendrocytes

Answer 29

produce the myelin sheath around axons in the CNS One oligodendrocyte makes multiple segments of myelin that wrap around several axons.

Question 30

Schwann Cells

Answer 30

produce the myelin sheath around axons in the PNS * Each Schwann cell makes one segment of myelin

Question 31

MS destroys...

Answer 31

Oligodendrocytes

Question 32

Myelin

Answer 32

acts as an electrical insulator to increase the speed of conduction along the axon → increases Rm and decreases C

Question 33

Ependymal cells

Answer 33

form the epithelial lining of the ventricles in theThe layer of ependymalderived cells surrounding the blood vessels of the choroid plexus produces cerebrospinal fluid (CSF). brain and the central canal of the spinal cord.