Rachel
About

Khan Academy on a Stick

Healthcare and medicine
  • Three Types of Muscle

    Find out what makes smooth muscle, cardiac muscle, and skeletal muscle similar and different from one another. Rishi is a pediatric infectious disease physician and works at Khan Academy.

  • Heart Cells Up Close!

    Get a close-up view of the cardiac cells and see what makes them different from the other (skeletal and smooth) muscle cells. Rishi is a pediatric infectious disease physician and works at Khan Academy.

  • Myosin and Actin
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    How myosin and actin interact to produce mechanical force.

  • Tropomyosin and troponin and their role in regulating muscle contraction
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    Tropomyosin and troponin and their role in regulating muscle contraction. How calcium ion concentration dictates whether a muscle is contracting or not.

  • Calcium Puts Myosin to Work

    See exactly how Calcium binds Troponin-C and allows Myosin to do some work. Rishi is a pediatric infectious disease physician and works at Khan Academy.

  • Sympathetic Nerves Affect Myosin Activity

    Check out how the amount of Myosin that is tugging on your heart can change depending on your activity level! Rishi is a pediatric infectious disease physician and works at Khan Academy.

  • Why Doesn't the Heart Rip?

    Understand LaPlace's law to see the effect that pressure, radius, and wall thickness each have on the "wall stress" in the left ventricle. Rishi is a pediatric infectious disease physician and works at Khan Academy.

Heart Muscle Contraction

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