The environment of the brain

Question 1

Function of glial cells

Answer 1

Support neuronesNourish and insulateRemove waste

Question 2

What are the three different types of glial cells?

Answer 2

AstrocytesOligodendrocytesMicroglia

Question 3

Which glial cell is hte most abundant?

Answer 3

Astrocytes

Question 4

Function of astrocytes

Answer 4

Glucose supply- have glycogen stores to produce pyruvate and lactateUptake of neurotransmitters- remove NT from synapsesBuffer K+ in brain ECF- do not let K+ level get above 12mM- facilitated by NaKATPase and NaK2Cl

Question 5

Function of oligodendroctes

Answer 5

Myelination of axons- like schwann cells in PNS

Question 6

Function of microglia

Answer 6

Immune cells of brain- dendritic and can change shape in response to foreign material- phagocytic- antigen presenting cells

Question 7

Describe the blood brain barrier

Answer 7

Barrier that limits diffusion of substances from the blood to the brain ECF to maintain the correct environment for the brain

Question 8

What does the BBB facilitate?

Answer 8

Gives the brain the control needed to prevents inappropriate neurone excitation. Protection from:Extracellular ion changesPeripheral hormonesDrugsPrevent CNS transmitters from entering the peripheral circulation

Question 9

Describe the structure of the BBB

Answer 9

Made up of endothelial cell of capillaries and astrocytes- Tight junction- Basement membrane surrounds the capillaryAstrocyte processes have:foot processes that adhere to capillary endothelial cells, enclosing barrierSends signals to maintain tight epithelial junctions

Question 10

What substances are able to pass through the BBB?

Answer 10

WaterLipid soluble molecules e,g, O2, CO2Molecules that need to be transported are:- glucose- amino acids- potassium

Question 11

Describe the immune response of the brain

Answer 11

Is immune privileged- prevents a significant immune response (inflammation) as the skull is rigid Microglia are APC and present phagocytosed products to T cells which can enter via post-capillary venules

Question 12

What are the excitatory amino-acids in the CNS?

Answer 12

Glutamate

Question 13

What are the inhibitory amino-acids in the CNS?

Answer 13

GABAGlycine

Question 14

What are the biogenic amines neurotransmitters?

Answer 14

AChNADopamineSerotoninHistamine

Question 15

What are the peptide neurotransmitters?

Answer 15

DynorphinEnkephalinsSunstance PSomatostatinCCKNeuropeptide Y

Question 16

What are the different types of glutamate receptors?

Answer 16

Ionotropic- AMPA (Na and K permeable)- NMDA (Ca permeable)- KainateMetabotropic- mGluR1-7(GPCR)

Question 17

Give a particular characteristic of NMDA receptors

Answer 17

Need to have glutamate bound in order for the cell to be depolarised, allowing Ca2+ entry

Question 18

What is the main NT found in over 70% of CNS synapses?

Answer 18

Glutamate

Question 19

Describe synaptic plasticity

Answer 19

Activation of NMDA and mGLuRs lead to AMPA up-regulationStrong, high frequency stimulation causes long term potentiation, which is the basis for long term synapse strengthening and learning

Question 20

What is a particular characteristic of glutamate?

Answer 20

Increased amount of glutamate can lead to excitotoxicity due to significant Ca2+ entry though NMDA receptors. - astrocytes remove NT to prevent this

Question 21

What ion channels are linker to GABA and glycine?

Answer 21

Integral Cl- channels- causes hyperpolarisation to decrease AP firing by inhibitory post synaptic potentials

Question 22

Where do you find high concentrations of glycine?

Answer 22

Spinal cordBrainstem

Question 23

Where do you find acetylcholine as a neurotransmitter?

Answer 23

NMJGanglion synapse in ANSPostganglionic in PSNS

Question 24

At which receptors does ACh act?

Answer 24

Nicotinic and muscarinic in the CNS

Question 25

Where are the cholinergic pathways in the CNS?

Answer 25

Originate in basal forebrain and brainstemProjects to cortex and hippocampus Also, have local cholinergic interneurones

Question 26

Degeneration of what neurones and where is seen in Alzheimers?

Answer 26

Cholinergic neurones in the nucleus basalis of Meynert

Question 27

Where do you find dopamine in the CNS?

Answer 27

Nigrostriatal pathway- motor controlMesocortical and mesolimbic pathways- mood, arousal and reward

Question 28

Degeneration of what neurones and where is seen in Parkinsons?

Answer 28

Dopaminergic neurones in the substantial nigra

Question 29

Where do you find NA in the CNS?

Answer 29

Neurones in the locus ceruleus and is release throughout the cortex, hypothalamus, amygdala and cerebellum- inactive during sleep- increased activity during behavioural arousal

Question 30

Where do you find serotonin in the CNS?

Answer 30

Locus ceruleus- involved in sleep, wakefulness, mood and in the vomiting centre