Nervous system: The role of glia Flashcards
What are the 3 types of glia and their general role?
- Astrocytes - most abundant, supporters
- Oligodendrocytes - insulators
- Microglia - immune response
What is the role of astrocytes?
- Structural support
- Help to provide nutrients to neurones via the glucose-lactate shuffle
- Remove neurotransmitters (important as glutamate can be toxic in high concs)
- Maintain ionic environment by buffering K+
- Help to form the BBB
Outline the glucose-lactate shuffle
Neurones dont produce glycogen so therefore astrocytes transfer lactate to supplement the glucose supply.
What do oligodendrocytes do?
Myelinate axons in the CNS - remember 1 oligodendrocyte can myelinate multiple axons at once
What is the role of microglia?
They recognise and are activated by foreign material and phagocytose. Form the brains main defence system
Whats the role of the BBB?
- limits diffusion of substances from blood to brain EC fluid
- maintains correct environment for neurones
What cells maintain the BBB?
Astrocytes
What are the main excitatory and inhibitory neurotransmitters in the CNS?
Excitatory: glutamate
Inhibitory: GABA, glycine (glycine is released by inhibitory interneurones and therefore present in the spinal cord and brainstem)
What are 2 types of ionotropic glutamate receptors?
AMPA receptors: Na/K - mediate initial fast depolarisation
NMDA receptors: Na/K/Ca - long term potentiation
What are the general roles of cholinergic pathways in the CNS?
What is the clinical consequence when these pathways degenerate?
Arousal, learning, memory and motor control.
Degeneration of cholinergic neurones in the nucleus basalis is associated with alzheimers - cholinesterase inhibitors are used for treatment.
Name the dopaminergic pathways in the CNS and their function
The nigrostriatal pathway - involved in motor control
The mesocortical and mesolimbic pathways - involved in mood, arousal and reward
What conditions can arise due to dopamine function in the CNS? How can they be treated?
Parkinsons: loss of dopaminergic neurones in the substantia nigra. Can be treated with levodopa (a dopamine precursor)
Schizophrenia:
