Lecture 4 - Synaptic Communication Flashcards
Neuroglia (glial cells)
->Traffic nutrients & maintain molecular/ionic stability
All around neuron, outnumber neurons
Astrocyte (glial)
-Physical support
-cleans up debris in brain (phagocytosis)
-control chem composition of environ.
-nourish neurons
Microglia (glial)
-Smallest
-immune system & protect from invading microorganism (brain)
Oligodendrocytes
-myelin sheath (CNS)
-processes like canoe paddles, wraps around axon segment
Saltatory conduction
Action potential jump from node of ranvier to other (cuz of myelinated axon)
Receptor protein
Detect & Communicate signal
-activated by NT
-activated by light, touch, smell, taste
Ionotropic receptor
Ion channel
-properties of pore determine EPSP (Na+ in) or IPSP (Cl- in)
-immediate change in permeability
Metabotropic receptor
Not ion channel
-trigger intracellular signalling cascade via G proteins (large but delayed signal cuz cascade effect)
-effects: change gene expression, open/close G protein gated ion channels
G protein gated ion channel
1) NT binds to metabotropic receptor
2) Activated G proteins transmit message intracellularly
3) some ion channels gated by activated G proteins (directly or indirectly)
G protein signalling cascades
1) open G protein-gated ion channels
2) change in gene transcription
3) secretion of substances from cell
4) Anything cell wants
Presynaptic inhibition & facilitation
Inhibition: Axoaxonic synapse hyperpolarize axon terminal (downstream neuron) , calcium channel not open very long, reduce NT released
Facilitation: depolarize axon terminal, calcium likely open with action potential, increase NT release
Autoreceptor (main presynaptic inhibition)
Receptor in presynaptic membrane activated when cell releases own NT (metabotropic, inhibitory)
