Imagine that you are casually strolling through the park on a warm spring day. As you pass underneath a tree, you notice a loud buzzing sound above you. You look up and are startled to see a large nest, swarming with hornets. How would you react to this situation? What role would your brain play in your reaction?

The human brain is locked in the skull, and cannot receive or send signals to the rest of the body on its own. Luckily, the brain is able to utilize the nervous system and the endocrine system, which help connect the brain to the body. Thanks to these systems, you would be able to react to the hornets' nest and escape safely.

Essential Questions

• What are the basic divisions of the nervous system?
• What are the subdivisions of the peripheral nervous system?
• How does the flight-or-flight response help us respond to stressful situations?
• What are the key components of the endocrine system, and how does this system communicate with the body and brain differently than the nervous system?