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Nervous Tissue

Nervous tissue includes all cells that provide communication between other tissue types.  Think of nervous tissue as the communication network of the body, consisting of a master computer(the brain) linked to multiple sites via complex cabling and wires(the spinal cord and nerves).  Various sensing devices(receptors) provide input to the computer and when necessary the computer controls machine response(effectors such as muscles or glands).

Nervous System Basics

  • receptors monitor conditions
  • sensory neurons transmit to the CNS
  • motor neurons send output to effectors from the CNS
  • Nerves do not contain neuron cell bodies
  • Nerves can contain processes of both sensory and motor neurons
  • most neuron cell bodies are found in the brain or spinal cord.  Those outside the CNS are in ganglia.

Now, examine the diagram and its components.  Find the receptor on the muscle cell.  As the muscle cell stretches or contracts, the receptor provides information about its activity.  Linking the receptor to the Central Nervous System(CNS) is the sensory neuron.  A chain of two or three sensory neurons enable information to reach the brain.  The brain processes incoming sensory information and when necessary sends output along motor pathways to the muscle.  Motor pathways as you can see also consist of a chain of two or three neurons.  The muscle, due to control exerted by the brain, functions normally.  Finally, note where the colored circles(neuron cell bodies) are located.  As you can see, most neuron cell bodies are located within the brain or spinal cord.  Processes or extensions of these neuron cell bodies pass through nerves.  A nerve then, is like a cable with many small wires, some transmitting  information into the CNS(sensory) with others conducting information out to body structures(motor).

Now, look at this image of a nerve in cross section!  Does it remind you of a cable with many wires?

As you look at slides containing nervous or other tissues, keep these points in mind:

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