Excitotoxicity

Question 1

Which neurotransmitter is excitatory

Answer 1

Glutamate

Question 2

What are fast receptors

Answer 2

Ionotriopic receptors -main ion that moves through is Na
(NMDA and AMPA receptors)

Question 3

What are slow receptors

Answer 3

Metabotropic receptor

Question 4

What neurotransmitter is inhibitory

Answer 4

GABA

Question 5

How does glutamate cause excitation

Answer 5

Glutamate binds to AMPA and NMDA channel receptor - sodium ions move through into the cell.
This removes the Mg on the NMDA receptor
Ca can now enter the cell through NMDA channel
Ca causes more AMPA receptors to be added to the membrane (positive effect)

Question 6

What causes a seizure

Answer 6

Imbalances between excitation and inhibition leading to desynchronisation of neuronal firing

Question 7

What is a seizure

Answer 7

Clinical manifestation of an abnormal excessive excitation of a population of neuron

Question 8

What is epilepsy

Answer 8

recurrent episodes of seizure which is unprovoked

Question 9

How can a stroke lead to development of seizures

Answer 9

Blood clot forms which prevents oxygen/ nutrients from accessing cells.
Na/K pump stops working, so cells depolarise and cause a rapid firing of action potentials.
Some neurons release glutamate at high rate, so cells are bombarded with glutamate
Cause excessive intracellular calcium levels (cells have been excited)

Question 10

How may a seizure lead to a spinal cord injury

Answer 10

Secondary acute spinal injury:

After influx of Na and Ca into a cell due to oversecretion of glutamate the cell will increase Cl uptake to balance the charge.
This disrupts the osmotic balance of the cell, creating a hypotonic environment so water enters the cell
Cell swells and ruptures leading to swelling around the spine

Question 11

How do local anaesthetics work

Answer 11

Bind to Na channels and inhibit an influx of Na so an action potential cannot be initiated