Neurochemistry Flashcards
What is the role of astrocytes?
Modify synapses
Control potassium ions
Control BBB
Neurotransmitter reuptake
What is the role of oligodendrocytes?
They form the myelin sheath of multiple neurons
What is the role of microglia?
Resident immune cells of the CNS
Engage in phagocytosis
What is the role of ependymal cells?
Ependymal cells line the ventricles
Produce monitor and circulate CSF
What is the role of vascular epithelial cells?
Line blood vessels and form part of the BBB
Where are axons located?
Distal to the cell body
Where are dendrites thpically located?
At the cell body
What are the three main divisions of neurons (polarity)?
Bipolar (olfactory, retinal)
Multipolar (purkinje, pyramidal)
Unipolar (dorsal root ganglion)
What kind of circuits exist in the CNS?
Divergence
Same pathway
Multiple pathways
Convergence
Multiple sources
Single source (multiple synapses between same two neurons)
Reverberating circuit (feedback system)
Parallel after discharge circuit
Where are vesicles stored?
Presynaptic terminal
Where are neurotransmitters made?
Cell body
What are the two forms of axonal transport?
Slow (1-5mm/day)
Fast (200-400mm/day) - neurotransmitters, growth factors, toxins, viruses
What are the three types of synapse?
Axodendritic - axon to dendrite
Axosomatic - axon to cell body
Axoaxonic- axon to axon
What are the two types of receptor?
Ionotropic - ligand-gated ion channels
Metabotropic - GPCRs
How do ligand gated ion channels function?
The binding of a ligand (eg neurotransmitter) changes the shape of the receptor, opening a channel for ions to flow through
Fast effects
Examples: NMDA, AMPA
How do metabotropic receptors function?
Agonist activates receptor
G protein is activated and produces effector
Effector stimulates 2nd messenger synthesis
2nd messenger activates intercellular process
Indirect, slower effect
What is the canonical 2nd messenger?
Cyclic AMP
On what level does a neurotransmitter work?
Single neuron/receptor level
Excitatory - depolarised the membrane and increases the probability of an action potential on that neuron
Inhibitory - hyperpolarises the membrane and decreases the probability of an action potential on that neuron
What would be the effect of serotonin acting on Gi coupled receptor?
Inhibitory
How might excitatory dopamine have an inhibitory effect in a circuit?
Activation of the D1 receptor on a GABA-ergic neuron would increase GABA release at the synapse
GABA would inhibit a downstream glutamatergic neuron