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Science

Health 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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Circulatory system

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, blood pressure, and lymphatics.
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Circulatory system diseases

Learn about some important diseases that affect your heart, blood vessels, and lymphatics.
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Respiratory system

Get a better understanding of how your lungs help you to sing and survive!
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Respiratory system diseases

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Nervous system and sensory information

Learn all about how your nervous system works to help your body communicate and respond to the environment.
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Executive systems of the brain

Learn all about the higher-order executive functions of the brain that help you remember your friend's name, learn a new language, and even fall asleep at night.
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Endocrine system

Our endocrine system allows the body to maintain a carefully balanced system that controls everything from fluid/electrolytes to how tall you grow!
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Hematologic system

Find out what's inside of blood!
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Musculoskeletal system

Our muscles and bones keep us moving and form the basic physical structure for the rest of our organ systems.
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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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Endocrinology and diabetes

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

Learn some basics about the Health Care system in the US
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Miscellaneous

Enjoy!
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!