Transmission Within A Neuron Flashcards
Information processing in a neuron…
Neurotransmitter input - electrochemical
Action potential in neuron - electrical
Synaptic transmission; neurotransmitter output - chemical
Neuron vs a transistor
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
Inside a neuron…
Organic anions-
k+
Water
The cell membrane…
Made of lipid (fat) and proteins
The barrier between intracellular and extracellular space
Outside neuron…
Cl-
NA+
Water
At resting potential…
More negative anions inside
More positive cations outside
Electrical potential - resting potential is -70mV
Ion concentrations …
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
Inside - outside of a neuron…
Chemical or osmotic gradient
Intracellular K+ wants out
Extracellular said Na+ wants in
In order to maintain the resting potential…
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
The structure of a neuron…
Input - processing - output - transmission to next neuron
The action potential…
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
An ion channel…
Is macro molecule/protein
Normally blocks ion flow
Changes structure when electrical field changes
Triggered by EPSP from dendrite
Depolarisation in action potentials is…
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
Re polarisation in action potential is…
When the membrane reaches +40mV sodium channels close and voltage gated potassium channels open. Potassium rushes out. The potential is -80mV
Recovery in action potential…
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
