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Nerve Impulses (Sensory Receptors (Neurons have very specialised cell…
Nerve Impulses
Sensory Receptors
Neurons have very specialised cell-surface membranes filled with many channel proteins. These are specialised to sodium and potassium channel proteins.
A receptor converts an external or internal stimulus into an electrical signal. Sensory receptors detect changes in their surroundings.
Voltage-gated channels are channel proteins which have a gate which, when open, allows a certain type of ion through.
Sensory neurons are energy transducers. They convert anything from pressure, to heat, and convert this into electrical energy.
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Resting Potential
The sodium potassium pump pumps out three sodium ions for every two potassium ions which it pumps in.
The neural membrane is often described as leaky as potassium ions will diffuse back out of the cell.
In this state there are more potassium ions inside of the cell and sodium ions outside of the cell. Using ATP, both ions can be actively transported, against their concentration gradient, across the membrane.
The inside of the cell has a negative overall charge compared to the exterior, as there are many different negative ions in the cytoplasm.
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