2.1 - Role of Neurones and Glia Flashcards
What are the 3 types of glial cells?
- Astrocytes
- Oligodendrocytes
- Microglia
What is the 5 roles of astrocytes?
- Structural support
- Helps Provides nutrition
- Remove neurotransmitters
- Maintain ionic environment by K+ buffering
- Help form BBB
How do astrocytes help provide energy for neurones?
Astrocytes produce lactate which is transferred to neurones to supplement their supply of glucose
How do astrocytes help to remove neurotransmitters? Why is this necessary?
Re-uptake of transmitters
Prevents excitation of neaby neurons and prevents formation of another EPSP
How do astrocytes help to buffer K+ in brain ECF?
K+ excreted from neurones into ECF and then can be taken up via Na+K+ATPase, K+ channel, or Na-K-Cl cotransporter of astrocyte
What is the function of oligodendrocytes?
Myelinate axons in CNS
What cell type myelinates axons in the PNS?
Schwann cells
What is the function of microglia? What germ layer is microglia derived from?
- Immune cells
- phagocytose debris and foreign material
- Derived from mesoderm
How is the BBB formed?
Formed by the brain capillaries having tight junctions between endothelial cells, and the end feet of astrocyte processes surrounding the BV
Whta are the 3 chemical classes of neurotransmitter in the CNS?
Amino acids
Biogenic amines
Peptides
What are the excitatory and inhibitory AA neurotransmitters?
Excitatory - Glutamate
Inhibitory - GABA and glycine
What are the ionotropic and metabotropic glutamate receptors? What are they permeable to?
Ionotropic:
- AMPA - Na and K
- Kainate - Na and K
- NMDA - NA, K, and Ca
Metabotropic:
- mGluR1-7
What is the co-agnosist of NMDA receptors?
glycine
How is long term potentiation achieved? What can go wrong?
NMDA receptors activated through strong, high frequency stimulation results in calcium entry into cell and up-regulation of AMPA receptors and easier depolarisation in the future.
Too much calcium however causes excitotoxicity
Of the inhibitory AAs, which is found primarily in the brain and which is mostly in th ebrainstem and spinal cord?
Brain - GABA
Brainstem and spinal cord - Glycine
How does GABA and glycine receptors cause hyperpolarisation of a cell?
GABA and glycine receptors have integral Cl- channels that hyperpolarise
What is the mechanism of action of barbiturates and benzodiazepines?
Both enhance the response to GABA and therefore have sedative and anxiolytic effects.
Explain how the patellar tendon reflex arc works
Hitting the patellar tendon results in activation of a sensory neuron in the quadriceps muscle which sends a signal to an excitatory motor synapse in the quadriceps and an inhibitory interneuron that connects to the hamstring muscle
What are the main areas of action of ACh?
- Neuromuscular junction
- ganglion synapse in ANS
- postganglionic parasympathetic
- CNS neurotransmitter at nicotinic and muscarinic receptors in brain
What are cholinergic pathways in the CNS linked to?
Arousal, learning & memory, motor control
What is the cause of Alzheimer’s disease? How is AD treated?
degeneration of cholinergic neurones in the nucleus basalis. treated with cholinesterase inhibitors
Name the 4 dopaminergic pathways in the CNS and what they are involved in
Nigrostriatal pathway - motor control
Mesocotrical and mesolimbic pathway - mood, arousal, and reward
tubero-hypophyseal pathway
What is PD associated with and how can it be treated?
Parkinsons associated with loss of dopaminergic neurons
Treated with levodopa (L-DOPA) which is converted to dopamine by AADC. However, you dont want dopamine to be produced outside of the brain so levodopa is coupled with carbidopa to inhibit AADC and the production of dopamine outside brain. Since carbidopa and AADC cant cross the BBB the LNAA (large neutral amino acid transporter) takes L-DOPA across the BBB and the AADC in the brain converts it to Dopamine
What is schizophrenia a disorder of and how can it be treated?
Possibly due to too much dopamine production and therefore antagonists of dopamine D2 receptors are given
Where can NA be found?
postganglionic sympathetic and neurotransmitter in CNS
What receptors does NA act through?
GPCR alpha and beta adrenoreceptors
Which group of neurons in the brain does most NA in the brain come from? What is their function?
Locus ceruleus - nucleus in pons
Function - arousal and wakefulness.
What is serotonin AKA?
5-HT
How do tricyclic antidepressants function?
Inhibit uptake of NA/5-HT
How do SSRIs work? What do they treat?
Treat depression and anxiety by inhibiting serotonin reuptake
What is a MAOI and how does it work?
Monoamine oxidase inhibitor
MAO metabolises monoamines and therefore MAOI inhibits this breakdown
