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2.1: Planning

Difficulty Level: At Grade Created by: CK-12
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Key Ideas

  • The nervous system is made up of the brain, the spinal cord, and a network of nerves connecting to all parts of your body.
  • Your brain acts as “mission control” to coordinate nerve messages throughout the body.
  • The skull, cerebrospinal fluid, and blood-brain barrier protect the brain's delicate nerve tissue.


The nervous system is introduced by inviting students to think about the brain. The brain is compared to a “super computer” and a “mission control.” It receives and transmits information from the environment through the sensory organs in order to maintain internal balance-homeostasis. Students investigate how the brain is protected by its own structure, by the skull, by the surrounding cerebrospinal fluid, and by the blood-brain barrier.



\begin{align*}\checkmark\end{align*} identify the components of the nervous system.

\begin{align*}\checkmark\end{align*} describe how the brain is the center for information transfer.

\begin{align*}\checkmark\end{align*} explain the relationship between the brain and sensory organs.

\begin{align*}\checkmark\end{align*} identify and evaluate the effectiveness of the structures that protect the brain.

\begin{align*}\checkmark\end{align*} explain the concept of homeostasis.


blood-brain barrier, brain, capillaries, central nervous system (CNS), cerebral cortex, cerebrospinal fluid, concussion, glial cells, homeostasis, meninges, nerve fibers, neuron, peripheral nervous system (PNS), spinal cord

Student Materials

Activity 1-1: The Blood-Brain Barrier (BBB)

  • Activity Report
  • Safety goggles
  • 6 test tubes with stoppers and a test-tube rack
  • Marking pen
  • Masking tape
  • Clear cooking oil to represent the membranes of the BBB
  • Sesame or motor oil to represent a fat soluble substance
  • Water with a little red food coloring to represent blood
  • Blue food coloring to represent a water-soluble substance
  • Alcohol
  • 3 eyedroppers
  • Paper towels
  • Colored pencils (red and blue)

Teacher Materials

Activity 1-1: The Blood-Brain Barrier (BBB)

  • Activity Report Answer Key
  • Diagram of brain in skull
  • Diagram/model of the Blood-Brain Barrier

Advance Preparation

See Activity 1-1 in the Student Edition

You may want to begin Activity 2-1: Big Brain on a Stick so that the completed models will be available when discussing Section 2.

Arrange to have some examples of protective headgear such as bicycle helmets and hard hats for students to refer to throughout this section.

Interdisciplinary Connections

Physical Education Compare a variety of sports safety helmets and discuss how their design helps protect the skull and brain.

Health Investigate which drugs cross the blood-brain barrier

Language Arts Write a persuasive essay about the laws regulating the wearing of protective helmets.

Social Studies Debate laws that regulate the wearing of protective helmets.

Visual Arts Create a drawing that shows how the blood-brain barrier protects the brain.

Math and Social Studies Investigate insurance, hospitalization, and rehabilitation costs for accidents related to head injuries due to not wearing head protection.

Background Information

The complexity of the human brain is greater than any other known matter. The brain constantly receives, integrates, and interprets information from the environment and then sends information to the muscles and major organs of the body. Some of the actions controlled by the brain are voluntary, while others are involuntary. Examples of involuntary responses are the functions of the heart, the lungs, and the digestive system. The brain is the central part of a much larger nervous system, which provides communication among cells in the body.

The nervous system uses sensors, such as the eyes and the ears, to convert the information it receives from them into messages it can process and then send to other parts of the body, such as the muscles, which respond. The brain and the spinal cord make up the central nervous system. The network of nerve cells that carry the messages to and from the central nervous system form the peripheral nervous system.

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