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Flashcards in Electrical Signals Deck (25):
1

AP generation

originated via receptor potentials or CNS postsynaptic potentials

2

Generator/receptor potentials vs. action potential

Change in membrane potential depends on stimulus magnitude

Response to stimulus graded

No refractory period and potential local spread passively

Possible TTX insensitive

3

Generator potential

Localized graded potential in sensory nerve terminal

4

Signal adaptation

Sensitive to rate of change of stimulus- event detection

Sensitive to duration- magnitude detection (rate of change or absolute change)

Slowly adapting is tonic and rapidly adapting is plastic receptors which can turn off

5

Chemical synaptic transmission

Stimulus to nerve or receptor to axon to post synaptic membrane via dendrites across synaptic cleft

6

Electrical signal

Less common than chemical ions flow through gap junctions

7

Chemical synapse

More common

Synaptic vesicles fuse with membrane and release to synaptic cleft and flow through postsynaptic channels

8

Pre synaptic terminal

Prepackaged vesicle of neurotransmitter

1 quantum is thousands of neurotransmitters

Pre synaptic depolarization from incoming AP

9

Pre synaptic depolarization

AP from excitation secretion coupling or Ca dependent process

10

Synaptic cleft

20-50 micrometers

Transmission by diffusion

Can contain neurotransmitter breakdown and recycling

11

Post synaptic response

Receptor subtype dependent (excitatory or inhibitory) and fast or slow

12

Ionotropic transmission

Small synaptic vesicles

Ligand gated ion channel on post synaptic ion channel to allow Na in

Fast transmission

With ACh membrane depolarization leading to muscle contraction

13

Metabotropic transmission

Slow chemical transmission

Large synaptic vesicles release out side of pre synaptic terminal

Bind receptor and activate G protein which has activated subunit open Na ion channel

Membrane hyperpolarization to decrease Heart rate (ACh)

14

Excitatory post synaptic potential

Becomes positive while inhibitory becomes more negative than resting potential

15

Post synaptic potential transmission

Goverened by physical properties of pre/post synaptic interaction

Dendrite size and axon hillock is important

Effects are receptor dependent

16

Excitatory postsynaptic potentials- Glutamate EPSP

Goes to glial cells and not post synaptic membrane, bind their receptors to allow Na flow into post synaptic membrane

17

GABA

Released to glial cell for glutamine production

GABA binds receptor and does not allow for activation of ion transport, IPSP in post synaptic membrane

18

Pre vs. post synaptic inhibition

Pre synaptic- modulatory neuron synapses on one collateral of the presynaptic neuron and selectively inhibits one target

Post synaptic inhibition all targets inhibited signal is below threshold so no AP and no response

19

Post synaptic potential is graded

Dependent on amount of neurotransmitter release

Dependent on number receptors available post synaptically

Summation can lead to compound EPSP

20

Summation

Occurs at the axon hillock

Potentials as PSP rises above threshold to get action potential

21

Neuronal integration

Signal transmission usually wide spread because of axonal divergence

Signal integration from multiple sources via synaptic convergence

22

Strychnine poisoning

Binds glycine inhibitory post synaptic receptors in spinal cord and medulla

Death from anorexia and exhaustion

23

Saxitoxin

Loss of excitatory neurotransmission (Na channel blocker AP)

24

Dendrotoxin

Prolonged presynaptic depolarization

25

Neuronal coding

Adaptation or rate

Rate: as intensity of stimulus increases frequency or rate of action potentials will increase

Adaptation: as intensity of stimulus increases or decreases can generate potential or not