PY 105 Chapter Notes - Chapter 2: Resting Potential, Cell Membrane, Membrane Potential
Neuronal Structure and Function
• Neurons are specialized cells that transmit and process information from one part of the body to
another
• Takes the form of an action potential - localized area of depolarization of the plasma membrane
that travels in a wave-like manner along an axon
• When an action potential reaches the end of a synapse, the signal is transformed into a chemical
signal with the release of a neurotransmitter, process called synaptic transmission
Structure of the Neuron
• Basic functional and structural unit of nervous system is the neuron
• Structure of these cells is highly specialized to transmit and process action potentials
• Neurons have a central body, the soma, which contains the nucleus and is where most of the
biosynthetic activity takes place
• Slender projections, called axons and dendrites, extend from the cell
• Neurons have 1 axon and many dendrites
o 1 dendrite = bipolar
o Many dendrites = multipolar
• Neurons generally carry action potentials in one direction, with dendrites receiving signals and
axons carrying action potentials away from cells body
• Axons can branch multiple times and terminate in synaptic knobs
o Chemical messengers are released and travel across a very small gap called the synaptic
cleft to the target cells
The Action Potential
• Resting membrane potential
o An electric potential across the plasma membrane of approximately -70 millivolts (mV)
o The interior of the cell is negatively charged with respect to the exterior
• Na+/K+ ATPase
o Pumps 3 Na+ out
o 2 K+ in
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