Transmission Within A Neuron Flashcards

1
Q

Information processing in a neuron…

A

Neurotransmitter input - electrochemical
Action potential in neuron - electrical
Synaptic transmission; neurotransmitter output - chemical

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2
Q

Neuron vs a transistor

A

Neuron - transistor
10,000’s of inputs - 2 inputs
Integration of inputs highly complex - integration of inputs follows a simple rule
Integration depends on chemical circumstances - integration is constant
1 output - 1 output

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3
Q

Inside a neuron…

A

Organic anions-
k+
Water

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4
Q

The cell membrane…

A

Made of lipid (fat) and proteins

The barrier between intracellular and extracellular space

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5
Q

Outside neuron…

A

Cl-
NA+
Water

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6
Q

At resting potential…

A

More negative anions inside
More positive cations outside
Electrical potential - resting potential is -70mV

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7
Q

Ion concentrations …

A

Ions passively move down chemical and electrical gradients. Sodium moves in and potassium moves out which reduces the resting potential to 0mV
Outside - inside a neuron is a massive electrical gradient which exceeds the fields strength of heavy lightning

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8
Q

Inside - outside of a neuron…

A

Chemical or osmotic gradient
Intracellular K+ wants out
Extracellular said Na+ wants in

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9
Q

In order to maintain the resting potential…

A

An active sodium-potassium pump needs to maintain resting potential by moving 3 NA+ outside and 2 K+ inside. This uses a lot of energy

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10
Q

The structure of a neuron…

A

Input - processing - output - transmission to next neuron

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11
Q

The action potential…

A

Is a very rapid, strong change of membrane voltage
It is set in its shape, it does not change amplitude for a stronger neuron
It is guided by voltage sensitive ion channels and massive electrical or chemical gradients

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12
Q

An ion channel…

A

Is macro molecule/protein
Normally blocks ion flow
Changes structure when electrical field changes
Triggered by EPSP from dendrite

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13
Q

Depolarisation in action potentials is…

A

When the membrane reaches a threshold of -55mV and the voltage gated sodium channels open and sodium rushes into the neuron
The potential is +40 mV

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14
Q

Re polarisation in action potential is…

A

When the membrane reaches +40mV sodium channels close and voltage gated potassium channels open. Potassium rushes out. The potential is -80mV

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15
Q

Recovery in action potential…

A

Is when the membrane hyper polarises. Potential is at -80mV

All the channels close and the sodium-potassium pump works to restore the normal ion balance. Potential returns to -70mV

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16
Q

The puffer fish is lethal because,..

A

Tetrodotoxin blocks sodium channels and prevents action potentials.
70 micrograms can kill you in 30 minutes

17
Q

Actual information processing of signals in neurons…

A

Occurs in dendrites and soma, inputs interact with each other here and a complex biophysical process decides whether an input is forwarded.

18
Q

The speed of an action potential …

A

About 2 metres per second in a regular neuron

In myelin and salutatorian conduction the speed is 17 metres per second

19
Q

What is myelin?

A

A fatty layer of insulation which is generated by Schwann cells and digodendrocytes
There is a loss of myelin in MS
Most axons are myelinated

20
Q

Salutatorian conduction is..

A

When myelin covers an axon with gaps and action potentials can jump from one node to another which is fast and efficient transmission