Flashcards in Physiology 1.9 Deck (18):
What are electrical synapses?
-connects large groups of neurons
-*cardiac muscle* (some smooth)
-large and unselective (metabolic signals can be passed)
What are chemical synapses?
synapses which release neurotransmitters
What is the advantage of electrical synapses?
wide-spread coordinated contraction, such as with the heart
What is the advantage of chemical synapses?
specificity for targeted neuron firing
How does calcium affect the release of ACh?
Ca2+ controls vesicle fusion and mobilization of synaptic vesicles
What are the 3 steps of transmitter release?
2) Discharge of transmitter by exocytosis
3) Recycling of membrane
What is the function of synapsin?
-Substrates for cAMP-dependent protein kinase and Ca2+/calmodulin-dependent protein kinase
-non-phos: bind the vesicles to actin filaments in the cytosol
-phos: release the vesicles, allowing them to move into the active zone
What is the function of Rab?
-hydrolysis of GTP helps *target* vesicle to docking site
-during exocytosis, Rab are recycled into cytoplasm
What is the function of the SNARE complex?
-Vesicle proteins (Synaptobrevin (VAMP)) interact with membrane proteins (SNAP-25 and syntaxin) to dock the vesicle to the presynaptic membrane
-Munc18 binds to syntaxin before VAMP binds to allow exocytosis of synaptic vesicles
What is the function of clostridial neurotoxins?
-cleave SNARE proteins and prevent vesicle fusion
How does tetanus work in the body?
targets and cleaves VAMP
How does botulinum work in the body?
cleave SNAP-25, VAMP, and syntaxin
What is alpha-latrotoxin?
-binds to neurexin (~syntaxin) to generate massive vesicle depletion and NT release
What is the function of synaptotagmin?
-binds with Ca2+ in presynaptic terminal
-triggers fusion with terminal membrane and NT release for FAST synaptic transmission
What are the criteria for neurotransmitters?
1) Synthesized in neuron
2) Present in presynaptic + released to affect postsynaptic/effector organ.
3) behaves same exogenously and endogenously.
4) specific way it is removed from the synaptic cleft
What are the types of uptake transporters?
-no Cl- dependence
-Na+ and Cl- cotransport
What are the uptake transporters for getting NTs into synaptic vesicles from cytoplasm?
-VMAT1/VMAT2: monoamines (dopamine, NE)