Glia

Question 1

what are the 4 types of neuroglia in CNS

Answer 1

astrocytes
oligodendrocytes
microglia
ependyma

Question 2

Function of oligodendrocytes

Answer 2

form myelin around axons

Question 3

Function of microglia

Answer 3

immune cells of the CNS, they patrol the cerebral environment to respond to pathogens
they act as immune cells and phagocytes

Question 4

function of ependyma

Answer 4

line ventricles of the brain and central canal of the spinal cord forming a barrier between the cerebrospinal fluid and the brains tissue

ciliated cells direct flow of cerebrospinal fluid

Question 5

3 types of neuroglia in the PNS

Answer 5

Schwann cells
satellite cells
enteric glia

Question 6

Two types of Schwann cells

Answer 6

myelinating and non-myelinating

Question 7

Function of myelinating Schwann cells

Answer 7

form the myelin sheath around peripheral axons acting as a crucial support cells for neuron maintenance and function

Question 8

Function of non-myelinating schwann cells

Answer 8

provide support and protection for smaller unmyelinated axons and promote nutrient transport

Question 9

Sizes of myelinated/non-myelinated axons

Answer 9

anything below 1micrometer in PNS is not myelinated and anything below 0.2 micrometers in the CNS

Question 10

function of satellite cells

Answer 10

astrocyte-like functions in PNS ganglia
they provide metabolic and structural support to sensory and autonomic neuronal cell bodies

Question 11

function of enteric glia

Answer 11

astrocyte-like functions in the GI tract
non-neuronal support cells of the guts own nervous system
they have similar morphological and functional properties to astrocytes in the brain
immune regulation

Question 12

Difference between PNS and CNS blood vessels

Answer 12

PNS blood vessels are leaky whereas CNS vessels are tight

Question 13

Blood vessels in the CNS

Answer 13

endothelial cells connected by tight junctions and surrounded by astrocyte processes

Blood brain barrier
permeability barrier

Question 14

Purpose of the blood brain barrier

Answer 14

protects brain from harmful substances in the blood

glucose and other nutrients are actively transported through BBB

if peripheral immune cells get into the brain it can trigger or worsen neuroinflammation leading to brain tissue damage

Question 15

When microglia are activated following injury they:

Answer 15

Increase macrophage and immune functions
become phagocytic

Question 16

Myelin: difference in PNS and CNS

Answer 16

PNS- Schwann cells
-each cell myelinates a single axon

CNS- oligodendrocytes
-each cell myelinates 20-30 axons

Question 17

Purpose of myelination

Answer 17

to insulate axons to greatly increase the speed of nerve conduction
- by making action potentials jump from node of ranvier to node of ranvier (saltatory conduction)

Question 18

What is white matter?

Answer 18

bundles of myelinated axons interconnecting brain regions enabling rapid integrated communication

Question 19

What does loss of myelin lead to

Answer 19

leads to axonal conduction block (the failure of action potentials to propagate along an axon)
and degeneration

Question 20

What are neuropathologies

Answer 20

diseases or disorders that affect the nervous system, including the brain spinal cord and nerves

Question 21

Structure of astrocytes

Answer 21

star shaped glial cells with numerous fine, branching processes called foot processes

Question 22

Two types of astrocytes

Answer 22

Protoplasmic astrocytes- extensive branching in grey matter

fibrous astrocytes- long filamentous projections in white matter

Question 23

What is neurogenesis

Answer 23

the creation of new neurones

Question 24

What is gliogenesis

Answer 24

The creation of new glial cells

Question 25

what is neuronal path finding

Answer 25

crucial developmental process where developing neurones extend their axons to find and connect with their specific target cells to form a functional neural network

Question 26

What is synaptogenesis

Answer 26

the process of forming new synapses between neurones in the brain, spinal cord and between neurones and muscle cells

Question 27

What is GFAP

Answer 27

glial fibrillary acidic protein a protein that is primarily found in astrocytes, it functions as a component of the astrocytes cytoskeleton helping to maintain cell shape and plays a role in response to disease and injury

Question 28

Astrocytes functions

Answer 28

take up glutamate at the synapse take up potassium released by neurones provide metabolic support for neurones

Question 29

What is glutamate

Answer 29

the main excitatory neurotransmitter in the brain released by many neurones in the brain

Question 30

Glutamate-glutamine shuttle

Answer 30

astrocytes take up glutamate at the synapse and recycle it, this terminates action at the synapse and stops glutamate from building up to toxic levels

Question 31

What happens when glutamate levels are too high?

Answer 31

Excitotoxicity - destruction of neurones

Question 32

Common cause of excitotoxicity

Answer 32

schema during stroke -lack of oxygen causes glutamate transporters to fail and glutamate accumulates

Question 33

Potassium in the nervous system

Answer 33

potassium is released from neurones during action potentials astrocytes take up K+ and stop it building up

Question 34

What happens when K+ build up

Answer 34

unregulated neuronal activity and epilepsy in some cases

Question 35

how Astrocytes provide metabolic support

Answer 35

neurones account for 90% of brain energy consumption but glucose is accumulated equally by neurones and astrocytes astrocytes use it as an additional energy source for neurones and act as energy suppliers

Question 36

Astrocyte-neurone lactate shuttle

Answer 36

astrocytes store glucose as glycogen and covert it to lactate when neurones need energy

Question 37

Neuronal injury in PNS vs CNS

Answer 37

nerves can regenerate in the PNS but not in the CNS

Question 38

PNS regeneration

Answer 38

dependant on the Schwann cells, they form a regeneration tube that guides and stimulates regrowth of the axon

Question 39

CNS regeneration inhibition

Answer 39

regeneration is inhibited by astrocytes which form a glial scar these are necessary because they prevent further inflammation and excitotoxicity

Question 40

what is a glial scar

Answer 40

a complex barrier than physically and chemically obstructs the regeneration of damaged axons

Question 41

Benefit of glial scars

Answer 41

in the brain when neurones are left to regenerate they cannot reconnect to their target neurone but rather the closest neurone this can have detrimental effects in the brain but not so much in the PNS