L6 Graded Potentials Flashcards

1
Q

Which cells are excitable?

A

Nerves and muscles

Can undergo rapid changes in their membrane

Can change their resting potentials into electrical signals

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2
Q

Resting Vm

A

Voltage across plasma membrane in a cell with no changes in membrane permeability

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3
Q

Neural communication is based on

A

Rapid change in membrane permeability to ions

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4
Q

Direction of synapse

A

Unidirectional

Dendrites to cell body down axon to dendrites of other neuron

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5
Q

Graded potential is

A

Change in potential when a neuron releases neurotransmitter onto the dendrites/cell body of another neuron

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6
Q

Signal that travels down axon is known as

A

The action potential

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7
Q

Vm at rest is

A

Negative =polarized

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8
Q

If Vm becomes less negative

A

More positive

Less polarized/depolarized

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9
Q

If depolarized plasma membrane returns to negative Vm is

A

Repolarized (more negative)

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10
Q

If plasma membrane becomes more negative the Vm rest

A

Hyperpolarized

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11
Q

Step 1 of graded potentials

3

A

Resting membrane exposed to chemical stimulus (signal comes in from presynaptic to postsynaptic neuron)

Chemically gated channels open

Membrane potential changes

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12
Q

A graded potential that depolarizes the membrane potential makes the neuron

A

More pos

More likely to fire

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13
Q

A graded potential that hyperpolarizes the membrane potential makes the neuron

A

More neg

Less likely to signal

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14
Q

Graded potential step 2

A

Movement of ions through channel produces local current

Depolarizes or hyperpolarizes nearby regions of cell membrane

Change in potential is proportional to stimulus
Farther away from source=less graded potentials

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15
Q

Summarize graded potential

3

A

Vary with size of stimulus

Decays with distance

May be depolarizing or hyperpolarizing

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16
Q

Graded potentials depend on what and what are the two kinds?

A

Permeability changes induced by neurotransmitter of postsynaptic neuron

Excitatory postsynaptic potential- EPSP
Inhibitory postsynaptic potential- IPSP

17
Q

EPSP causes what

A

Depolarization

More likely to fire

Na+ or Ca2+

18
Q

IPSP causes what

A

Hyperpolarization

Less likely to fire

Cl- or K+

19
Q

Summation of postsynaptic potentials

A

One neuron may receive input from 1000s of other neurons simultaneously

Whether it fires depends on whether net input is excitatory or inhibitory

20
Q

For a neuron to fire it has to reach what voltage?

A

-50mV

Roughly +15mV change (-70 to -55)

21
Q

Typically EPSP has a voltage of

A

0.5mV (lasts 20msec)

22
Q

A typical neuron would need how many EPSPs to reach threshold?

23
Q

Temporal summation

A

Single synapses receives many EPSPs in short period of time

1 neuron firing many times rapidly

24
Q

Spatial summation

A

Single synapse receives many EPSPs from many presynaptic cells

25
Magnitude of graded postsynaptic potential (GPSP) depends on
Sum of activity in all presynaptic inputs Only if EPSP is reinforced by other supporting signals through summation will info be passed on
26
Interaction of EPSPs and IPSPs allows
A fine degree of discrimination and control in determining what info will be passed on