Lp3 Flashcards
(25 cards)
A very small gap between excitable cells through which synaptic transmission, or neurotransmission occur?
Synapse (chemical)
Synaptic Fxn:
Neurotransmission?
Inhibition?
Summation?
Neuromodulation?
Neurotransmission: transmitting signals
Inhibition: blocking transmission
Summation: integrating impulses
Neuromodulation: changing transmission
Synapse type of substance released?
Chemical: NTs diffuse across synapse
Electrical: gap jcts
Synapse structural connection b/w neurons:
Axodentrictic?
Axosomatic?
Axoaxonic?
Dendrodentritic?
Axsodentritic: usually excitatory
Axosomatic: inhibitory
Axoaxonic: modulation
Dendrodentritic: local interactions
Events at the presynapstic neuron reduce excitation at the?
Postsynaptic one
Synapse site of inhibition?
Postsynaptic (fast)
Presynaptic (slow)
NT released from inhibitory neuron leads to hyperpolarization of motor neuron?
Postsynaptic (fast)
A neuron provides interference, reducing the size of the Postsynaptic potential of a motor neuron?
Presynaptic (slow)
AP reaches axon terminal
+
Ca2+ gates open
+
Ca2+ enter cell; leads to fusion of synaptic vesicles & cell membrane
+
NTs exocytosed into synaptic cleft
+
NTs diffuse across synaptic cleft & bind to post-synaptic membrane receptors
Neurotransmission sequence of events
Effect of NT binding receptors=
Gated channels on the Postsynaptic membrane open (leads to depolarization or hyper-polarization- a graded potential is initiated)
Termination of Nt effects
-degradation
-re-uptake
-diffusion
Different channels mediate excitatory & inhibitory effects on postsyanptic membranes:
-sodium ion channels?
-potassium ion channels?
-Chlorine ion channels?
-NA: excite
-K: inhibit
-CL: inhibit
Changes in RMP?
Excitation: depolarization; neurons closer to AP threshold (more +)
Inhibition: hyperpolarization; membrane potential farther from threshold (more -)
Graded potentials may:
Summation & generate AP: EPSP (excitatory post-synaptic potential)
Inhibit an AP: IPSP (inhibit a Tory post-synaptic potential)
Graded potentials occur on
Dendrites and cell bodies
APs occur at
Axon hillock or along axon
Diffuse across the synapse is relatively slow=
Synaptic delay
Synaptic delay reflects 3 events
-release of NT molecules
-diffusion of NT across synapse
-specific binding to receptors and conformation changes opening channels
Communication along:
-short pathways=
-multi-synaptic pathways=
-short= rapid
-multi= slower
Rapid release of NTs from Presynaptic neuron(s) leads to many sequential depolarizations=
Temporal
Excessive neurons release NTs simultaneously & converge on a single neuron=
Spatial
Neuromodulation: postsynaptic affects?
-cell metabolism
-synthesis
-release & degradation/ uptake of NTs
-hormonal activity
Influx of cations moves membrane potential closer to -55mv & generation of AP=
Na+ channels
Efflux of cations & membrane potential becomes more (-)=
K+ channels
