Neural tissue is specialized for TRANSMISSION OF ELECTRICAL IMPULSES… this
is the way that messages are transmitted and received in your body.
In a very general sense, the job of the nervous system is to receive SENSORY IN (could
be from outside, or inside your body); and transmit MOTOR OUT (response to sensory).
In between, there is much coordination and integration… but moving information in and
out is the basic job.
Neurons – generate electrical impulses and thus communicate
Neuroglia – support cells for neurons – separate and protect, supportive framework,
regulate composition of interstitial fluid.
(Many more neuroglia than neurons)
Many ways to divide the nervous system:
1. Central vs. peripheral
Central nervous system – spinal cord and brain.
Integrating, processing, coordinating
sensory data and motor commands.
Sensory – information in; motor – response out.
Peripheral nervous system - neural tissue outside CNS – delivers sensory info and carries
motor commands to peripheral tissues.
What we think of as “nerves” are bundles of
axons carrying information into and out of CNS.
Sensory vs. motor
Sensory is moving information into the CNS (afferent)
Motor is moving information out of the CNS (efferent)
Sensory can also be divided into:
pain, temperature, touch, pressure, vibration, proprioception
Some of this is relayed to CNS and we are conscious of it (perception), some is
General sensory information is relayed to the general sensory area of the
olfaction, vision, taste, equilibrium, hearing.
Receptors for these
are located in sensory organs, and info is provided to specific sensory cortexes…
thus they are special, in that they have their own special place to be sensed.
Somatic (voluntary) vs. autonomic (involuntary)
Different parts of your body are run by different divisions of the nervous system…
anything voluntary (skeletal muscle) is somatic; involuntary (heart, breathing, gland
secretion, etc) is autonomic.
Autonomic can also be divided into:
increase HR, breathing, dilate pupils… “fight or flight”
decrease HR, breathing, increase digestion and urine
production… “rest and digest”
Structure of a neuron:
Cell body: Large round nucleus.
slender processes out from cell body – highly branched – information comes
into cell body from here.
Axon – long process that propagates electrical impulses known as action potentials.