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Nervous System: Organization & Reflex Arc

Nervous System: Organization & Reflex Arc

Author: Meg O'Mahony

To demonstrate an understanding of the Organization of the Nervous System as well as the purpose and mechanism of the Reflex Arc, you need to be able to:

  1. summarize the main roles of the nervous system in the body.
  2.  state the structural and functional relationships between
    •  the central and peripheral nervous systems.
    • the somatic and autonomic nervous systems.
    • the sympathetic and parasympathetic nervous systems.
  3. describe the location and function of the spinal cord.
  4. describe the structure and function of, and be able to label,  the parts of a neuron including: axon, dendrite, cell body, myelin sheath, Schwann cell and nodes of Ranvier.
  5. distinguish among motor, sensory and interneurons in terms of function and location.
  6. describe the structure and function of a reflex arc, both in words and diagrammatically
  7. carry out a practical examination of some human reflexes; communicate data collected effectively in a table, chart or graph
  8. state and apply the all or none principle to nerve transmission.
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Nervous System: Organization and the Reflex Arc

This introduction to the Nervous System identifies the roles and some keys terms then explains how the whole system is organized. The Central Nervous System is discussed, then the Peripheral Nervous System is broken into the Autonomic and Somatic Systems. Each of these systems can be further classified. The Sympathetic and Parasympathetic Systems make up the Autonomic System while the Sensory and Motor Systems make up the Somatic Nervous System. The Central Nervous System is described in more detail before the Reflex Arc is explained. Part of your in-class work will be an activity testing some of each other's reflexes.

Source: M. O'Mahony, open source images

The Reflex Arc

This tutorial shows how a stimulus-response action can happen without the Brain's involvement. These are simple actions, often used for protection. The follow-up to this tutorial will be your Reflex Arc activity in class.

Source: M. O'Mahony, open source images

Student Notes Template

Template that complements the tutorial for students to take notes. Also contains the diagrams in the tutorial.


Source: M. O'Mahony, open source images,

Spongelab videoclips and games :-)

Go to and log-in.  (If you haven't set up an account yet, do's free.)

Do a search for "neuron".  In the list of resources that come up, explore:


-how do we remember things?

-neuron signals

-human nervous system


-visualizing neurons in the brain


-your brain on drugs




There are also some excellent graphics available here as well!


The Reflex Arc

This is the lab that you will be performing to test reflex responses on yourself and your classmates.



Tutorial: Organization of the Nervous System

Another explanation of Nervous System organization accompanied by figures.

Source: Jim Bidlack, University of Central Oklahoma, based on an original activity by Melissa Pickering, Innerbody Direct, and Scott Sheffield, Get Body Smart from MERLOT (Multimedia Educational Resource for Learning and Online Teaching) CalTech

Interactive Nervous System

Examination of the Nervous System.  Allows for some interactivity in the 3D presentation.

Nice, but don't get bogged down in details - you don't need to know them.

Source: MERLOT (Multimedia Educational Resource for Learning and Online Teaching) CalTech Inner Body

Reflex Arc

Short (< 1 min) overview of the action of a Reflex Arc

Source: YouTube

What is Your Reaction Time?

This is a neat lab from Stanford University Museum of Technology that explores reaction time by catching a dropping ruler. Explanations for results are provided.


Source: Stanford University, Museum of Technology

Tour Your Neural Circuits

Check out some of the activities on this site...particularly "nervous system explorations" and "the basics".

Source: url above

Reflex Arc

Another short video but with more detailed information and terminology.

Source: EdukiteLearning, YouTube

Reflex Arc - detailed

A much more detailed video about the Reflex Arc. You will need to finish the next tutorial on the Action Potential before you will be able to understand some of the details.

Source: J. McFadden, YouTube

Fact Sheet on the Reflex Arc

An excellent Fact Sheet on the Reflex Arc can be found at

I have requested permission to post this directly.  Until then (or if), the above url will get you to the sheet.

It has a good explanation with many good examples - as well as some questions to check your understanding.

Source: Martin Griffin, Curriculum Press, ISSN 1351-5136