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Flashcards in Neurones And Glia Deck (41):
1

What do glia do?

Support, nourish and insulate neurones
Remove waste

2

Name the types of glia

Astrocytes
Oligodendrocytes
Microglia

3

Which is the most abundant those of glia cell

Astrocytes

4

Functions of astrocytes?

Structural support
Provide nutrition for neurones via glucose-lactose shuttle
Remove neurotransmitters
Maintain ionic environment by buffering K+
Form part of blood brain barrier

4

How is the supply of glucose to neurones supplemented?

Astrocytes produce lactate which is transferred to neurones via the glucose-lactate shuttle (because neurones cannot store or produce glycogen)

5

Describe how the glucose lactate shuttle works

Glucose taken into the astrocyte from the bloodstream via GLUT1

Glucose -> glycogen -> pyruvate -> lactate

Lactate transported to interstitial pace via MTC1 along with H+

Transported into the neurone via MCT2 along with H+ where it is metabolised

6

When is the glucose-lactate shuttle used?

When there is high demand/very active - only supplies glucose for about 5 mins

7

How do astrocytes remove neurotransmitters?

Have transporters for transmitters to keep the extracellular concentration low

8

Why do astrocytes need to buffer potassium and how?

Potassium is released into the extracellular space by neurones and can cause depolarisation of a neurone if it builds up

Taken up by astrocytes via
🔹Na-K-ATPase
🔹Na-K-2Cl
🔹Potassium channels

9

What is oligodendrocytes do?

Myelinate axons in the CNS - the equivalent of Schwann cells in the PNS

10

What is the role of microglia?

Immunocompetent cells
-recognise foreign material and are activated
-dendritic processes swell so they can phagocytose foreign material
-brain's main defence system

11

Which embryonic tissue is the CNS derived from?

Endoderm

12

Which embryonic tissue are microglia derived from?

Mesoderm

13

Functions of the blood brain barrier?

Limit diffusion of substances from the blood to the extracellular fluid
Maintain the correct environment for neurones

14

What makes up the blood brain barrier?

Tight junctions between endothelial cells of capillaries

Basement membrane surrounding the capillary

Foot processes of astrocytes

15

What are some substances that can be transported across the blood brain barrier?

Glucose
Amino acids
Potassium

16

Which molecules can diffuse freely across the blood brain barrier?

Gaseous molecules and water
Lipophilic molecules

17

What is meant by saying the CNS is immune privileged?

Has a specialised immune function

T-cells can enter the CNS but their inflammatory response is limited

Any inflammatory expansion in the CNS would not be tolerated due to rigidity of the skull

18

What is the axonal hillock?

Where the action potential is generated to pass along the axon

Connects the cell body to the axon

19

Name the different categories and types of neurotransmitters

Amino acids
-glutamate
-GABA
-glycine

Biogenic amines
-NA
-dopamine
-serotonin
-histamine
-ACh

Peptides
-dyphorin
-enkephalins
-substance P
-somatostatin
-CCK
-neuropeptide P

20

Which are the main neurotransmitters to cause an excitatory response?

The amino acids - glutamate

21

What are the two main types of glutamate receptors?

Inonotrophic - integral ion channel which increases the Na and K permeability, and sometimes Ca

Metabotrophic - a GPCR which allows changes in IP3 or (decreased) cAMP levels

22

What are the main ionotrophic receptors and what do they do?

AMPA: increase Na and K permeability

NMDA: increase Na, K and Ca permeability

Kainate receptors

23

What does it mean if a receptor is excitatory?

Will cause depolarisation and subsequently allow more action potentials to fire
(Excitatory Post-Synaptic Potential - EPSP)

24

How are glutamate receptors thought to have memory?

Activation of NMDA and mGluRs can lead to upregulation of AMPA receptors

25

How can excessive amounts of glutamate cause cell death?

Can get too much entry of calcium due to activation of NMDA receptors so that intracellular concentration of calcium becomes too high

26

Which are the two main inhibitory neurotransmitters and where do they act?

GABA in the brain

Glycine in the brainstem and spinal cord

27

How do GABA(A) and glycine receptors inhibit action potentials?

They are integral Cl ion channels

Opening of the channels results in hyperpolarisation and this results in decreased action potential firing

(Inhibitory Post-Synaptic Potential - IPSP)

28

Which drugs bind to GABA receptors and what is their effect?

Barbiturates
Benzodiazepines
Cause sedation and anti-anxiety

29

Which neurotransmitters act as neuromodulators?

Biogenic amines and ACh
(Regulate a diverse population of neurones)

30

What is the role of ACh in the CNS?

Acts as an excitatory neurone on nicotinic and muscarinic receptors
On receptors present on pre-synaptic terminals to enhance the release of other neurotransmitters

31

What is the effect of ACh in the brain?

Arousal
Memory
Learning
Motor control

32

What is the degeneration of cholinergic neurones associated with?

In the nucleus basalis of Meynert - Alzheimer's disease

33

What is the distribution of cholinergic neurones?

Distributed widely through the CNS
Originate in the basal forebrain and brainstem
Have diffuse projections to many parts of the cortex and hippocampus

34

What functions are dopamine receptors involved in?

Motor control
Mood
Arousal
Reward

35

Where are noradrenaline receptors found?

On post-ganglionic effectors synapses in the SNS

In the CNS - operate as a GPCR in the cortex, hypothalamus, amygdala and cerebellum

36

What increases the release of noradrenaline and dopamine?

Amphetamines

37

What is a decrease in noradrenaline associated with?

Depression

38

What are peptide neurotransmitters often involved in?

Pain regulation

39

What are the three dopamine pathways in the brain and what are they involved in?

Nigrostriatal: motor control

Mesocortical and mesolimbic: mood, arousal and reward

40

What is the pathway/projection of noradrenergic neurones in the brain?

Cell bodies of noradrenaline-containing neurones located in the brainstem (pons and medulla)

Diffuse release of NA thoughout the cortex, hypothalamus, amygdala and cerebellum