OCB: NT 1 glutamate, GABA and ach

Question 1

function of CNS synapses

Answer 1

either fire or do not fire AP

Question 2

what is the firing of an AP determined by?

Answer 2

number and strength of excitatory and inhibitory inputs - this provides an integrated response

Question 3

what do excitatory inputs do

Answer 3

depolarise

Question 4

what do inhibitory inputs do

Answer 4

hyperpolarise

Question 5

how can neurotransmitters work

Answer 5

modulate activity on ion channels in pre synaptic terminal (Ca channels) or control excitability of post synaptic terminals (K channels)

Question 6

what is glutamate

Answer 6

the major excitatory neurotransmitter in the CNS (not always excitatory)

Question 7

how common are glutamate containing neuron terminals in the CNS

Answer 7

they are in abundance

Question 8

what are prominent glutamatergic pathways

Answer 8

• cortico-cortical pathways (concerned with processing)
• pathways between thalamus and cortex
• extrapyramidal pathway (the projections between the cortex and striatum)
• other glutamate projections exist between the cortex, substantia nigra, subthalamic nucleus and pallidum

Question 9

what are glutamatergic pathways involved in

Answer 9

• neuro-circuitry of memory, emotions and cognition
• implicated in various psychiatric conditions such as depression, anxiety, schizophrenia and drug addiction
• also involved in some excitotoxic disorders - too much excitability of neurons and they get damaged

Question 10

properties of glutamate as an amino acid

Answer 10

• one of the most abundant in the body
• non-essential as it is synthesised from alpha-ketoglutaric acid which comes from the citric cycle
• cannot cross BBB so is synthesised in the brain from metabolism of glucose
• also synthesised from glutamine by glutaminase which is produced by astrocytes

Question 11

how is glutamate synthesised from glutamine

Answer 11

• by glutaminase (produced by astrocytes)
• glutamine enters pre synaptic neuron where it is converted into glutamate
• glutamate released by exocytosis and after its done its job it is taken up by astrocytes and converted back into glutamine by glutamine synthase

Question 12

what are the types of glutamate receptor

Answer 12

ionotropic

metabotropic

Question 13

what are the families of glutamate receptors in mammals

Answer 13

AMPA, Kainate, NMDA and metabotropic glutamate receptors