The Role of Neurones and Glia Flashcards Preview

2.4.1. Nervous System > The Role of Neurones and Glia > Flashcards

Flashcards in The Role of Neurones and Glia Deck (43):
1

An important source of dopamine for the motor system can be found in which structure?

Substantia nigra

2

Which cell type can assume a macrophage-like appearance when activated?

Microglia

3

Which cell type is primarily responsible for maintenance of the BBB?

Astrocytes

4

What are the peripheral side effects of L-DOPA?

Tend to be GI related
- nausea
- anorexia

5

How are the side effects of L-DOPA ameliorated by giving carbidopa?

1) L-DOPA to dopamine by AADC (aromatic amino acid decarboxylase)

2) increased dopamine = GI side effects

3) carbidopa inhibits AADC = decreased side effects

6

What is the somatic nervous system?

Part of the peripheral NS

Responsible for voluntary muscle and reflex arc

7

What is the autonomic nervous system?

Parasympathetic and sympathetic NS

Controls bodily functions not consciously directed

8

What structures are in the peripheral NS?

Dorsal and ventral roots

Spinal nerves

Peripheral nerves

9

What structures are in the central NS?

Cerebral hemispheres

Brainstem and cerebellum

Spinal cord

10

Describe the blood supply of the brain

Anterior, middle and posterior cerebral arteries

11

Describe the cranial meninges

Dura mater - tough fibrous layer, adhered to bone (periosteal, meningeal)

Arachnoid layer - CSF present in subarachnoid space

Pia mater

12

What types of glia cells exist in the nervous system?

Astrocytes

Oligodendrocytes

Microglia

13

Astrocytes

Most abundant glial cell

Structural support

Provide nutrition for neurones = glucose-lactate shuttle

Remove excess neurotransmitters = important for glutamate as its toxic

Though K+ buffering = maintain ionic environment

Help form BBB

14

How do astrocytes provide energy for neurones?

Astrocytes supplements their supply of glucose

2 lactate is produced and transferred into the neurone

Lactate is then transformed into pyruvate

15

Why do astrocytes need to buffer K+?

High levels of neuronal activity = [K+] rise in brain ECF

Astrocytes take up the K+ to prevent this

Otherwise would change the pH and damage neurones

16

What cell type myelinate in the CNS vs the PNS?

CNS = oligodendrocytes

PNS = schwann cells

17

Outline the role of oligodendrocytes

Insulators

Responsible for myelinating the CNS

18

Describe microglia

Immunocompetent cells

Recognise foreign material = activated = change shape = phagocytose

Can act as APCs and present Ags to T cells that can enter the CNS

19

What is the role of the blood brain barrier?

Limits diffusion from blood to brain extracellular fluid = maintain environment for neurones

Formed by tight junctions between endothelial cells in the capillary, surrounded by astrocytes

20

What substances are transported across the BBB?

Glucose

AA

K+

21

What substances can get freely through the BBB?

H2O

O2

CO2

Hormones

22

How does the immune system in the CNS vary from the immune response in the rest of the body?

CNS inhibits initiation of pro-inflam T cell response = don’t want to much inflam in a bone box

Does not undergo rapid rejection of allographs

23

Outline the structure of a typical neurone

Cell soma

Dendrites

Axon

Terminals

24

Describe the neruotransmitter release

Depolarisation in terminal = opens voltage-gated Ca2+ channels = Ca2+ ions enter terminal

Vesicles fuse = release transmitter

Neurotransmitter diffuses across the synaptic cleft = binds to receptors on postsynaptic membrane

25

What types of receptors can be present on the postsynaptic membrane?

Ligand-gates

GPCR

26

What are the 3 main classes of neurotransmitters?

AA

Biogenic amines

Peptides

27

Describe AA neurotransmitters

Excitatory AA = glutamate

Inhib AA = GABA, glycine

28

How can glutamate receptors be classified?

Ionotropic = ion channels permeable to Na+/K+, activation causes depolarisation

Metabotropic = GPCR, changes in IP3 or inhib of adenylate cyclase

29

Explain glutamate receptors role in learning and memory

Activation of NMDA receptors (and mGluRs) can up-regulate AMPA receptors(initial fast depolarisation)

Strong, high frequency stimulation causes long term potentiation (LTP)

Ca2+ entry through NMDA receptors important for induction of LTP

30

Where are inhibitory AA neurotransmitters found?

GABA – brain

Glycine – brainstem and spinal cord

31

Explain how GABA and glycine receptors are inhibitory

GABA and glycine receptors have Cl channels

Open Cl = hyperpolarisation = inhibitory post-synaptic potential = decreased AP

32

What drugs enhance the response to GABA?

Barbiturates = anti-epileptic

Benzodiazepines = sedative, anxiolytic

33

What biogenic amines exist?

Acetylcholine

Dopamine

Noradrenaline

Serotonin (5-HT)

mostly act as neuromodulators

confined to specific pathways

34

What is the role of acetylcholine as a neurotransmitter?

neuromuscular junction

ganglion synapse in ANS

postganglionic parasympathetic

35

Outline the cholinergic pathways in the CNS

Pathway arising the the nucleus basalis (first to die in Alzheimer’s)

Projects throughout the cerebral cortex

Septal neurones projecting into the hippocampus (LTP)

Involved in arousal , learning & memory

36

Outline the dopaminergic pathways in the CNS

Substantia nigra (first to die in parkinsons) to striatum involved in motor control

Mesolimbic pathway to amygdala and hippocampus – control of mood, arousal, reward

37

What conditions are associated with dopamine dysfunction?

Parkinson’s = loss of dopaminergic neurones, treat: levadopa converted to dopamine

Schizophrenia = too much dopamine, treat: antagonists at dopamine D2 receptors

38

Outline noradrenaline as a neurotransmitter

transmitter at postganglionic – effector synapse in ANS

Also acts as a neurotransmitter in the CNS

Operates through G protein-coupled α- and β-adrenoceptors

39

Outline the noradrenergic pathways in the CNS

Locus coeruleus contain noradrengeneric neurones (pons/medulla)

Diffuse release of NA throughout

40

Outline how noradrenaline effects behavioural arousal

Locus ceruleus inactive during sleep

Activity increases during behavioural arousal

Depression associated with deficiency of NA

41

Where does noradrenaline come from?

NA comes from neurones in the locus ceruleus

42

Outline the serotonergic pathways in the CNS

Serotonin from the raphe nuclei to the rest of the brain

Function: sleep/wakefulness, mood

43

What can be used for the treatment of depression and anxiety disorders

SSRIs = selective serotonin reuptake inhibitors