Chemical Messengers Flashcards
(74 cards)
Inhibitory post-synaptic potentials
small, localized hyperpolarizations usually assoc w/ Cl into cells via ligand-gated Cl channels
make AP less likely
Excitatory post-synaptic potentials
produced by Na or Ca into cell via ligand gated channels
make cell more excitable & increase probability of an AP
Summation
IPSP + EPSP (temporal or spatial)
if brought to threshold, cell will have an AP
Ligand gated receptors
many subunits from many genes
at least 1 subunit binds NT
binding opens pore so ion that selects for can enter cell
metabotropic receptors
large membrane-spanning receptors
coded by 1 gene
ligand binding site on extracell surface
ALL exert post synpatic effects via 1 or more 2nd messenger systems
Gs
activate AC which increases cAMP production
cAMP activates PKA which phosphorylates other proteins
can affect protein synthesis @ level of gene
Gi
inhibit AC so decrease cAMP production & PKA activity
Gq
activate phospholipase C which generates IP3/PIP & DAG
IP3 activates Ca2+ release from intracell Ca2+ stores
Jak Stat pathways
assoc w/ growth & have tyrosine kinase activity upon ligand binding
can then phosphorylate STAT protein which can move to nucleus & activate synthesis of various proteins
Axonal Transport
must move organelles or products for neurotransmission from soma to pre-synaptic terminal
what is transported via fast axonal transport
carry NT vesicles from cell body to synapse
what is transported via slow axonal transport
cytostructural components or ion channels/receptors
what is retrograde transport
movement from synapse to cell body
why is retrograde transport important
crucial to transport neurotrophic substances from synapse back to cell body, can exert trophic effects on neuron or transport used vesicles for degradation
criteria for a chemical to be an NT
neuron releasing the NT contained appropriate synthetic machinery to make NT & contains the NT itself
substance released in chemically or pharmalogically identifiable form
exogenous application of NT reproduces post-synaptic effects seen when presynaptic neuron stimulated naturally
blocking the receptor for the chemical blocks the effects of activating the pre-synaptic neuron
there are mechanisms for deactivating/termination the action of the chemical
Cholinergic System
any synapse that uses Ach as NT of choice
in CNS: critical for consciousness (damage to cholinergic areas leads to comatose state)
5 NTs of Monoamine System
epinephrine, norepinephrine, dopamine, histamine, serotonin
What are the catecholamines & what are they derived from?
dopamine, norepinephrine, epinephrine
all derived from tyrosine
What is norepinephrine assoc w/ in the brain?
waking up from sleep & alerting response
What is dopamine role in brain?
producing pleasure (damage assoc w/ Parkinson’s)
What is histamine role in brain?
from histidine & plays important role in waking you up from sleep
What is serotonin role in brain?
from tryptophan, critical in mood (targeted by anti-depressants)
What are the inhibitory amino acids?
AAs that inhibit neuronal activity
in CNS: glycine & GABA
Glycine location & fxn
found in spinal cord (some in medulla)
produces hyperpolarization by opening CL- channel w/ binding & its release assoc w/ some of spinal cord reflexes that lead to abrupt muscle relaxation if lift something too heavy