Signalling & Receptord in the CNS (Block 4) Flashcards
***** YOU WERE LATE BC OF COURSE REP MEETING, WATCH RECORDING TO CATCH UP
Signalling WITHIN neurones is primarily:
Electrical
Where is an action potential generated?
Pre-synaptic neurone
Are action potentials excitatory or inhibitory?
They’re ALWAYS excitatory; it’s responses in the post-synaptic cell that can be one or the other
Depolarisation definition
Excitation of neurone (by making membrane potential more +ve)
Hyperpolarisation definition
Inhibition of neuronal activity (by making membrane potential more negative)
Signalling BETWEEN neurones is always:
Chemical
How does the action potential lead to neurotransmitter release?
Action potential arrives at termina
Voltage-gates ca2+ channels open
Ca2+ entes the cell and signals to the vesicles
Vesicles move to the membrane
Docked vesicles release neurotransmitter by exocytosis
Neurotransmitter diffuses across the synaptic cleft and binds to receptors
Glial cells make up what percentage of the brain cells?
~90
Glial cells - astrocytes
Key mediators of neurovascular and neural network activity
Maintain nutrition and regulate ionic concentrations
Regulate external chemical environment by removing excess k+
Play a role in neurotransmitter synthesis and metabolism
Actively participate in chemical signalling, acting as ‘inexcitable neurons’
Glial cells - oligodendrocytes
Produce myelin, which insulates nerve cell membranes
A single one can extend to process 50 axons, wrapping~1micrometer of myelin sheath around each axon
Each one forms one segment of myelin for several adjacent axons
Glial cells - microglia
Act like macrophages, scavenging unwanted materials from the brain
Proliferate in disease states
Account for 10-15% of all cells in the brain & for active immune defence
Respond to pathogens by becoming activated
Blood-brain barrier
Physical separation of the brain from the rest of the body
Formed from astrocyters, neurons, and endothelial cells
