Quiz 6 Flashcards
Electrical synapse
result of gap junctions
bi-directional signaling
direct electron coupling
second cell mirrors the first cell
chemical synapse
synaptic cleft= gap between neurons
anterograde
signals pre- to post-synaptic
axon terminal has mitochondria, ER, and vesicles
vesicles loaded with NT bind to mem and release NT into synaptic cleft
Events at Chemical Synapse: 1
axon potential depolarizes axon terminal
Events at Chemical Synapse: 2
depolarization opens voltage-gated Ca channels; Ca flows into cell
Events at Chemical Synapse: 3
Ca entry triggers exocytosis of vesicle contents
Events at Chemical Synapse: 4
NT diffuses across synaptic cleft and binds to receptors on post-synaptic cell
Events at Chemical Synapse: 5
NT binding initiates a response in post-synaptic cell
- rapid short-acting fast synaptic potential
- slow synaptic potentials
Vesicle Cycle
- exocytosis
- endocytosis
Exocytosis steps
- filling of NT
- vesicle translocation
- docking
- priming
- fusion with membrane
Endocytosis steps
- membrane translocation
- coating with clathrin
- fission of coated vesicle from membrane
- uncoating from clathrin
- recycling (by several paths)
Two types of Post-synaptic responses
rapid short-acting fast synaptic potentials
slow synaptic potentials
rapid short-acting fast synaptic potentials
neurocrine signal opens ligand-gated ion channels
- more Na in- EPSP (excitatory depolarization)
- more K out/Cl in- IPSP (inhibitory hyperpolarization
slow synaptic potentials
neurocrine signal reaches G protein coupled receptor
this activates second messenger pathway
- may open/close ion channels
- may modify existing proteins or regulate synthesis of new proteins
may open/ close ion channels causes…
open
- more Na in (EPSP)
- more K out/Cl in (IPSP)
close
- less Na in (IPSP)
less K out/Cl in (EPSP)
may modify existing proteins or regulate synthesis of new proteins causes…
coordinated intracellular response
NMJ: Pre-synaptic components
synaptic knob
synaptic vesicle
NMJ: Post-synaptic components
motor end plate
Ach receptors
Acetylcholinesterase
synaptic knob
expanded end of neuron
synaptic vesicles
membrane-bound sacs filled with ACh
synaptic cleft
narrow space separating synaptic cleft from motor end plate
motor end plate
region of sarcolema (plasma membrane) across from synaptic knob (with folds and indentations to increase surface area)
ACh receptors
in motor end plate; bind to ACh
Acetylcholinesterase (AChE)
enzyme in synaptic cleft that breaks down ACh
NMJ Step 1
neuron action potential invades terminal
NMJ Step 2
Ca enters voltage gated ion channels
NMJ Step 3
ACh release
NMJ Step 4
ACh binding opens ion channels
NMJ Step 5
Na entry
NMJ Step 6
local current between depolarized end plate and adjacent muscle plasma membrane
NMJ Step 7
muscle fiber action potential initiation
NMJ Step 8
propagated action potential in muscle plasma membrane
NMJ Step 9
ACh degradation
Skeletal muscle is made up of
connective tissue
nerves and blood vessels
muscle fascicle: made up of muscle fibers
motor unit
a single motor neuron and the muscle fibers it controls
