Science & Economics

Healthcare and medicine

The medical world can be a confusing place. Patients and their families might feel overwhelmed by the large vocabularies and complicated explanations they get from their health care providers. Students entering health care also struggle to grasp the complexity of health sciences, and are forced to memorize huge amounts of information. We hope to make understanding the medical world a bit easier. Look around! These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video.
Community Questions
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MCAT Video Competition

Make videos for our MCAT Video Competition! More details at: https://www.khanacademy.org/about/med-competition
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The Heart

Your heart sits in the middle of your chest and pumps blood from about 4 weeks after conception until the day that you die. It never stops, and over your lifetime it will pump ~175 million liters of blood. To visualize that, imagine the amount of water that falls over Niagara falls in a few minutes. Remarkable! This little pump is the size of your clenched fist and in an adult can weigh about 300 grams. Watch these videos to learn more about how the heart works, blood flow in arteries and veins, and blood pressure.
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The Lungs

Get a better understanding of how your lungs help you to sing and survive!
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Influenza

Most people have had the flu virus at least once in their lives, and it’s usually not a pleasant experience… Fight back with some good information! Learn about typical flu symptoms (and how tell it apart from the cold), and how the flu virus invades your cells to cause disease. Finally, learn how flu vaccines may help prevent you from getting sick, and how we can test and treat the flu just in case you get really ill. Stay healthy, my friends!
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Blood

Find out what's inside of blood
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Blood Vessel Diseases

Learn about how arteries differ from veins and how arteries can get damaged over time.
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Fetal Circulation

Find out how the heart and circulatory system work in the fetus!
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Arterial Stiffness

Find out why having "stiff arteries" can increase blood pressure and cause uneven blood flow. It all comes back to the idea of "total energy"!
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Healthy Lifestyle

Learn some of the fundamentals behind staying healthy: Reducing your salt, keeping your weight in a healthy range, and exercising regularly.
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Endocrinology and Diabetes

Learn about hormones and diabetes, as well as some important information on glucose control.
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Health Care System

Learn some basics about the Health Care system in the US
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Colon Disease

Get a ring-side seat as a pathologist talks about colon cells under the microscope.
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Cervical Spine

Learn about the cervical (neck) spine through an Xray!
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Hypertension

Learn all about hypertension: symptoms, diagnosis, and how lifestyle changes can make a difference!
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Lab Values and Concentrations

Ever wonder about your lab values and what they mean? Lab values measure amounts of electrolytes or cells in your blood and occasionally tell you about how hormones and enzymes are working! Dive deeper and get a good understanding of concentrations as well!
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Heart Disease and Stroke

Find out what can cause a heart disease and stroke, and how the two are related!
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Heart Muscle Contraction

Find out more about heart muscles and what happens when they contract.
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Heart Depolarization

Check out the flow of positive charge through the heart that happens every time your heart beats! Learn how the heart is able to keep a regular rate and rhythm throughout your life.
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Nerve Regulation of the Heart

Learn how the sympathetic and parasympathetic nerves regulate your heart in so many different ways!
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Pressure Volume Loops

Watch as the pressure and amount of blood inside the left ventricle go up and down within fractions of a second!
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Changing the PV Loop

Find out how preload, afterload, and contractility work together to change your PV Loop (and affect stroke volume and cardiac output)!
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Preload and Afterload

Find out exactly what preload and afterload mean, and why most of us use a handy shortcut to guess-timating what they are!
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Miscellaneous

Enjoy!