Video 37 Notes
Nerve Impulse
โ Neurons conduct and transmit electrochemical signals throughout the body. These signals
relay information about a personโs surroundings from sensory organs to the brain. Then
from the brain, back to the body to tell it how to respond.
โ The most important concept to understand when learning about how neurons work would
be the notion of membrane potential.
โ Electric potential describes the amount of work that must be done to separate oppositely
charged particles that are attracted to one another.
โ Gravitational potential describes the amount of work that must be done to move a
massive object away from the source of a gravitational field.
โ Electric potential describes the work that can be produced by the spontaneous motion of
charged particles along their concentration gradients.
โ When looking at a resting neuron, the permeability of sodium is very low, because
sodium ion channels are typically closes, while potassium has a higher permeability since
potassium ion channels are open.
โ When a neurotransmitter arrives at a neuron and binds to an ionotropic receptor in the
cell membrane, this will cause a conformational change in the receptor such that ions can
pass through.
โ Depolarization excites the neuron, making it more likely to fire, while hyperpolarization
inhibits the neuron, making it less likely to fire.
โ The molecular world operates on the order of picoseconds, which are trillionths of a
second, meaning that billions of chemical events can happen quickly enough on this tiny
scale to produce a macroscopic effect, such as the motion of your body parts.
โ When neurotransmitters are received by a neuron, if the effect is a depolarization, this is
called an excitatory postsynaptic potential, or EPSP.
โ If the effect is hyperpolarization, we know this results in inhibition called inhibitory
postsynaptic potential or IPSP.
โ Multiple IPSPs produce a single IPSP of greater magnitude.
โ One EPSP and IPSP will cancel each other out.
