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leaves the cell
The number and
layout of the
dendrites are key
different types of
neurons. A = axon; D = dendrites, S = soma 38 Functional Classification of Neurons
Sensory (afferent) neurons are triggered by
stimuli in the physical environment and transmit
this information to the brain.
Interneurons process the signals locally or
transmit the information to other brain sites. This
is the largest class and accounts for all of the
neuronal processing in the cerebral cortex.
Motor (efferent) neurons carry signals to the
various muscles in the body. 39 The Other Cells of the Brain - Glia
Not usually directly involved in signal processing
Provide structural support for neurons, and also
are key players in transferring energy from the
vasculature to neurons
Provide electrical insulation to axons (called
myelin) that increases the speed of neural
Peripheral nerve (crosssectional view) insulated by
myelin from Schwann cell 40 Astrocytes
A major type of glial cell
that provides much of
the brain’s structural
support and firmness Astrocyte Maintains an adequate
Forms the blood-brain
that grow around
them with myelin Blood vessel Astrocytes
barrier 41 Oligodendrocytes and Schwann Cells
Both are glial cells that provide insulation to
neurons by forming myelin sheaths:
Insulating material in the CNS
Insulating material in the peripheral nervous
system 42 Electrical activity in neurons
The membrane potential:
The fluids inside the neuron (intracellular fluid) and outside the
neuron (extracellular fluid) are full of ions that have positive or
negative charges. Channels and ion pumps in the nerve cell
membrane determine which ions can move freely between the
inside and outside of the cell.
The balance of these ions determines the membrane
potential across (between the inside and outside)...
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This document was uploaded on 02/16/2014.
- Winter '13