Communication in the nervous system Flashcards
What are neurons?
Neurons are individual cells in the nervous system that receive, integrate, and transmit information.
What is the soma or cell body?
The soma, or cell body, contains the cell nucleus and much of the chemical machinery common to most cells
What are dendrites?
Dendrites are the parts of a neuron that are specialized
to receive information.
What is the axon?
The axon is a long, thin fiber
that transmits signals away from the soma to other neurons or to muscles or glands.
What is the myelin sheath? What is its purpose?
The myelin sheath is insulating material that encases
some axons. Myelin wrapping functions to speed up the transmission of signals that
move along axons
What is the terminal buttons?
The axon ends in a cluster of terminal buttons, which are small knobs that secrete
chemicals called neurotransmitters.
What is a synapse?
A synapse is a junction where information is transmitted from one neuron to another
Summarize the structure of a neuron.
To summarize,
- information is received at thedendrites,
- is passed through the soma and along the axon,
- and is transmitted to the dendrites of other cells at meeting points called synapses.
What are glia?
Glia are cells found throughout the nervous system that provide various types of support
for neurons.
Is transmission and integration of information exclusive to neurons?
Until recently, it was thought that the
transmission and integration of informational
signals was the exclusive role of the
neurons. However, newer research has
demonstrated that glial cells also play an
important role in information processing.
Describe the environment around a neuron.
Both inside and outside the neuron are fluids containing electrically charged atoms and molecules called ions. Positively charged sodium and potassium ions and negatively charged chloride ions flow back and forth across the cell membrane, but they do not cross at the same rate. The difference in flow rates leads to a slightly higher concentration of negatively charged ions inside the cell. The resulting voltage means that the neuron at rest is a tiny battery, a store of potential energy.
What is the resting potential of a neuron?
The resting potential of a neuron is its stable, negative charge
when the cell is inactive.T his charge is about 270 millivolts,
roughly one-twentieth of the voltage of a flashlight battery.
What is an action potential?
An action potential
is a very brief shift in a neuron’s electrical charge
that travels along an axon.
How does an action potential occur?
When the neuron is stimulated, channels in its cell membrane open, briefly allowing
positively charged sodium ions to rush in. For an
instant, the neuron’s charge is less negative, but then
it gradually becomes positive, creating an action
potential
What is the absolute refractory period?
The absolute refractory
period is the minimum length of time after an
action potential, during which another action
potential cannot begin.
