Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now: https://www.khanacademy.org/science/ap-biology/cell-communication-and-cell-cycle/cell-communication/v/intro-to-the-endocrine-system

Basic overview of hormones and the endocrine system. Created by Sal Khan.

Watch the next lesson: https://www.khanacademy.org/science/health-and-medicine/advanced-endocrine-system/endocrine-system-introduction/v/endocrine-gland-hormone-review?utm_source=YT&utm_medium=Desc&utm_campaign=healthandmedicine

Missed the previous lesson? https://www.khanacademy.org/science/health-and-medicine/hematologic-system-diseases-2/myeloproliferative-disorders/v/what-is-primary-myelofibrosis?utm_source=YT&utm_medium=Desc&utm_campaign=healthandmedicine

Health & Medicine on Khan Academy: No organ quite symbolizes love like the heart. One reason may be that your heart helps you live, by moving ~5 liters (1.3 gallons) of blood through almost 100,000 kilometers (62,000 miles) of blood vessels every single minute! It has to do this all day, everyday, without ever taking a vacation! Now that is true love. Learn about how the heart works, how blood flows through the heart, where the blood goes after it leaves the heart, and what your heart is doing when it makes the sound “Lub Dub.”

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