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This ion is more concentrated outside the neuron at rest.
Na+
This ion is more concentrated inside the neuron at rest.
K+
Neurons that carry information from receptors to the central nervous system.
Sensory neurons
Neurons that carry signals from the central nervous system to muscles or glands.
Motor Neurons
Neurons found within the CNS that connect sensory and motor neurons.
Interneurons
What is an action potential?
A rapid change in membrane potential that travels along the axon.
What is the resting membrane potential?
-70mV
The fatty layer that surrounds some axons and speeds up transmission.
Myelin Sheath
These gaps in the myelin sheath enable saltatory conduction
Nodes of Ranvier
The part of the neuron that consolidates the information from other neurons
Axon Hillock
What is saltatory conduction?
Impulses jumping between Nodes of Ranvier
3Na+ out, 2K+ in
The phase where sodium channels open and the membrane becomes more positive.
Depolarisation
The phase where potassium channels open and the membrane returns to negative.
Repolarisation
The phase where the membrane potential becomes more negative than resting.
Hyperpolarisation
Why is more K+ leaving than Na+ entering the cell
The neuron is negative at rest.
What is contiguous conduction?
Conduction down the axon that isn't insulated by Schwann cells, resulting in a slower more efficient conduction.
The minimum membrane potential required to trigger an action potential.
-55mV
Channels that contribute the most to the value of RMP
Potassium leak channels
What leads to Action Potentials happening?
Temporal/Spatial summation of EPSPs and IPSPs at the dendrites and soma which reach the threshold.
How is the RMP in neurons maintained?
A balance between passive diffusion through the leak channels and the sodium potassium pump.
Name the parts on a neuron (max of 500 points, 100 points per part)
Accept whatever is correct
What is the all or nothing principle and how is it explained?
The idea that action potentials either happen fully or not at all.
Voltage gated sodium channels can only open at -55mV and above.
What is the absolute refractory period and how is it explained?
The voltage gated Na+ channels are inactivated for a short while after being depolarised, and cannot reopen.
What is the relative refractory period and how is it explained?
APs can still be stimulated, though a larger extent of depolarisation is needed.
Voltage gated K+ ion channels are still open that repolarises the neuron, so more Na+ needs to rush out to counteract it.