Neuron - ANS-an electrically excitable cell that processes and transmits information
through electrical and chemical signals.
Nerve impulse - ANS-a signal transmitted along a nerve fiber. It consists of a wave of
electrical depolarization that reverses the potential difference across the nerve cell
membranes. It is the same regardless of the stimulus. aka action potential
Functional Classes of Neurons - ANS-Grouped by direction in which nerve impulse
travels relative to CNS - Sensory Neurons, Interneurons, or Motor Neurons.
General Regions of Neurons - ANS-Dendrites, Cell Body, and Axon.
Dendrites - ANS-Receptive region of the neuron along with the cell body. Receive
stimuli from the environment or from other neurons. Highly branched. Typically covered
with ligand-gated ion channels. Convey incoming messages toward cell body as graded
potentials (short distance signals).
Cell Body (Perikaryon) - ANS-Contains the nucleus and other organelles. Biosynthetic
center of neuron that synthesizes proteins, membranes, and other chemicals. Part of
receptive region and can convey graded potentials to axon hillock due to presence of
ligand-gated channels.
Axon - ANS-Carries information away from the cell body and toward other cells. Can
convey action potentials due to the presence of voltage-gated channels.
Axon Hillock - ANS-Origin of the axon from the cell body.
Initial Segment - ANS-This segment of the axon lies distally adjacent to the axon hillock.
It is where an action potential is initiated due to the presence of voltage-gated channels.
Axon Terminals - ANS-The axon ends at this terminal, which is also known as synaptic
terminals, where the neuron communicates with other cells. Synaptic vesicles
containing neurotransmitter are present.
, Myelin - ANS-A membranous wrapping that coats axons and increases the speed of
nerve impulse transmission due to saltatory conduction. Produced by oligodendrocytes
in CNS and Schwann cells in PNS.
Nodes of Ranvier - ANS-The small unmyelinated gaps along the axon that contain
voltage-gated channels.
Basic principles of electricity - ANS-Opposite charges attract each other.
Energy is required to separate opposite charges across a membrane, e.g. Na+/K+
pump.
Energy is liberated when the charges move toward one another.
If opposite charges are separated, the system has potential energy.
Voltage - ANS-is a measure of potential energy generated by separated charge. Greater
charge difference between points = higher voltage.
Current - ANS-is flow of electrical charge (Ions) between two points that can be used to
do work.
Membrane Potential - ANS-The unequal charge distribution across the plasma
membrane. Measured in millivolts.
Polarization - ANS-Any state when the membrane potential is not 0mV.
Depolarization - ANS-Any shift from the resting potential toward a more positive value.
This applies to changes in potential from -70mV to smaller negative values (toward 0
mV) as well as to membrane potentials above 0 mV.
Repolarization - ANS-When the chemical stimulus is removed, the membrane returns to
its normal resting potential.
Hyperpolarization - ANS-A shift in the membrane potential past resting levels. Potential
becomes more polarized (more negative) than resting potential.
Resting Membrane Potential - ANS-The membrane potential of an undisturbed cell.
Typically, -70 mV in neurons. Due to sodium-potassium pump moving ions, many
potassium leak channels, and a few sodium leak channels.
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