UNIT OVERVIEW

Your body has two main systems for sending messages: the nervous system (which you studied in Lesson 1) and the endocrine system. The nervous system sends fast electrical signals. The endocrine system sends slower chemical signals called hormones through your blood.

Think of it this way: the nervous system is like a phone call (fast and direct), while the endocrine system is like sending a letter (slower but the message lasts longer).

In this unit, you will learn:

• Where the endocrine glands are located and what they do
• Which hormones each gland produces
• How hormones control blood sugar, growth, and reproduction
• What happens when glands produce too much or too little hormone
• How negative feedback keeps hormone levels balanced

What you need to know already:

• Human Reproduction (Term 1) — sex hormones and the menstrual cycle
• Nervous System (Lesson 1) — how nerves send signals
• Grade 11: Effects of drugs on the body

Where this leads: This unit prepares you for Homeostasis in Humans (Lesson 3), where you will see how hormones help keep your internal environment stable.

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