If you're seeing this message, it means we're having trouble loading external resources for Khan Academy.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Endocrine system

7 videos
3A: Glands are special organs that secrete chemical messages called hormones, which seep into the blood - it’s like putting a tea bag in hot water. As the heart pumps, this blood carries these chemical messages throughout the body, allowing the hormones to interact with specific target cells and organs. Endocrine glands help us to maintain our appetites, grow up, metabolize molecules, concentrate urine,- and oh, so much more! We will examine how these variegated hormones play a role in homeostasis as the body responds to a changing environment.

Endocrine gland hormone review

VIDEO 11:39 minutes
Welcome to the Endocrine System. Get ready to learn about one of the most important ways that our body parts communicate! By Ryan Patton.

The hypothalamus and pituitary gland

VIDEO 6:35 minutes
What makes the endocrine organs tick? Find out in this video about the hypothalamus and pituitary glands!  By Ryan Patton.

Hormone concentration metabolism and negative feedback

VIDEO 4:47 minutes
In this video we're going to learn about how the concentration of hormones in our blood is regulated. By Ryan Patton.

Types of hormones

VIDEO 10:02 minutes
There are three major types of hormones, based on structure, in our body. Lets find out a little more about them. By Ryan Patton.

Cellular mechanism of hormone action

VIDEO 8:23 minutes
Learn about the interaction between chemical messages and their target cells in this video about hormone action. By Ryan Patton.

From terpenes to steroids part 1: Terpenes

VIDEO 7:49 minutes
Steroids have to come from somewhere, right? Let's learn about the carbon building blocks with which steroids are made. By Ryan Patton.

From terpenes to steroids part 2: Squalene, cholesterol, and steroids

VIDEO 4:29 minutes
After learning about terpenes, lets see how are body uses them to eventually make all the steroid hormones of our body. By Ryan Patton.