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Nervous System (synapse -tala (When an action potential reaches the end…
Nervous System
synapse -tala
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neurotransmitter is a chemical that dif- fuses across a synapse and binds to receptors on the dendrite of a neighboring neuron. This causes channels to open on the neighboring cell and creates a new action potential.
Once a neuro- transmitter has been released into a synapse, it does not remain there for long.
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Potential -Munirah
Resting
Proteins found in the plasma membrane work to counteract the diffusion of the sodium ions and potassium ions
Recall that ions tend to diffuse across the plasma membrane from an area of high concentration of ions to an area of low concentration of ions.
When a neuron is at restit is not conducting an impulse.,
These proteins, called the sodium-potassium pump, actively transport sodium ions out of the cell and potassium ions into the cell.
Action
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The speed of an action potential varies. Many axons have a covering of a lipid called myelin, which forms an insulating layer, called a sheath, around the axon.
Action potentials are described as being “all or nothing,” meaning that a nerve impulse is either strong enough to travel along the neuron or it is not strong enough.
For every two potassium ions pumped into a neuron, three sodium ions are pumped out. This maintains an unequal distribution of posi- tively charged ions, resulting in a positive charge outside the neuron and a negatively charged cytoplasm inside the neuron.
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