Electrical Signals

Question 1

AP generation

Answer 1

originated via receptor potentials or CNS postsynaptic potentials

Question 2

Generator/receptor potentials vs. action potential

Answer 2

Change in membrane potential depends on stimulus magnitude

Response to stimulus graded

No refractory period and potential local spread passively

Possible TTX insensitive

Question 3

Generator potential

Answer 3

Localized graded potential in sensory nerve terminal

Question 4

Signal adaptation

Answer 4

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

Question 5

Chemical synaptic transmission

Answer 5

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

Question 6

Electrical signal

Answer 6

Less common than chemical ions flow through gap junctions

Question 7

Chemical synapse

Answer 7

More common

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

Question 8

Pre synaptic terminal

Answer 8

Prepackaged vesicle of neurotransmitter

1 quantum is thousands of neurotransmitters

Pre synaptic depolarization from incoming AP

Question 9

Pre synaptic depolarization

Answer 9

AP from excitation secretion coupling or Ca dependent process

Question 10

Synaptic cleft

Answer 10

20-50 micrometers

Transmission by diffusion

Can contain neurotransmitter breakdown and recycling

Question 11

Post synaptic response

Answer 11

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

Question 12

Ionotropic transmission

Answer 12

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

Question 13

Metabotropic transmission

Answer 13

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)

Question 14

Excitatory post synaptic potential

Answer 14

Becomes positive while inhibitory becomes more negative than resting potential

Question 15

Post synaptic potential transmission

Answer 15

Goverened by physical properties of pre/post synaptic interaction

Dendrite size and axon hillock is important

Effects are receptor dependent

Question 16

Excitatory postsynaptic potentials- Glutamate EPSP

Answer 16

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

Question 17

GABA

Answer 17

Released to glial cell for glutamine production

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

Question 18

Pre vs. post synaptic inhibition

Answer 18

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

Question 19

Post synaptic potential is graded

Answer 19

Dependent on amount of neurotransmitter release

Dependent on number receptors available post synaptically

Summation can lead to compound EPSP

Question 20

Summation

Answer 20

Occurs at the axon hillock

Potentials as PSP rises above threshold to get action potential

Question 21

Neuronal integration

Answer 21

Signal transmission usually wide spread because of axonal divergence

Signal integration from multiple sources via synaptic convergence

Question 22

Strychnine poisoning

Answer 22

Binds glycine inhibitory post synaptic receptors in spinal cord and medulla

Death from anorexia and exhaustion

Question 23

Saxitoxin

Answer 23

Loss of excitatory neurotransmission (Na channel blocker AP)

Question 24

Dendrotoxin

Answer 24

Prolonged presynaptic depolarization

Question 25

Neuronal coding

Answer 25

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