Physiology 1.9 Flashcards Preview

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Flashcards in Physiology 1.9 Deck (18):
1

What are electrical synapses?

-gap junctions
-fast
-bidirectional
-connects large groups of neurons
-*cardiac muscle* (some smooth)
-large and unselective (metabolic signals can be passed)

2

What are chemical synapses?

synapses which release neurotransmitters

3

What is the advantage of electrical synapses?

wide-spread coordinated contraction, such as with the heart

4

What is the advantage of chemical synapses?

specificity for targeted neuron firing

5

How does calcium affect the release of ACh?

Ca2+ controls vesicle fusion and mobilization of synaptic vesicles

6

What are the 3 steps of transmitter release?

1) Targeting
2) Discharge of transmitter by exocytosis
3) Recycling of membrane

7

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

8

What is the function of Rab?

-binds GTP
-hydrolysis of GTP helps *target* vesicle to docking site
-during exocytosis, Rab are recycled into cytoplasm

9

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

10

What is the function of clostridial neurotoxins?

-cleave SNARE proteins and prevent vesicle fusion

11

How does tetanus work in the body?

targets and cleaves VAMP

12

How does botulinum work in the body?

cleave SNAP-25, VAMP, and syntaxin

13

What is alpha-latrotoxin?

-spider toxin
-binds to neurexin (~syntaxin) to generate massive vesicle depletion and NT release

14

What is the function of synaptotagmin?

-binds with Ca2+ in presynaptic terminal
-triggers fusion with terminal membrane and NT release for FAST synaptic transmission

15

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

16

What are the types of uptake transporters?

1) glutamate
-Na+/K+ exchange
-no Cl- dependence

2) NT
-Na+ and Cl- cotransport

17

What are the uptake transporters for getting NTs into synaptic vesicles from cytoplasm?

-VMAT1/VMAT2: monoamines (dopamine, NE)
-VGAT: GABA
-VAChT: ACh

18

What powers the vesicle transporters during neurotransmitter uptake?

H+ gradient