Learn about electrical conduction in heart cells. [7:45]

This lesson will explain and identify the components of the cardiac conduction system. It is 1 of 2 in the series titled "Cardiac Conduction System Overview."

Go through the similarities and differences between the sarcomere and a slingshot! This video explores a contraction in terms of what happens to the interaction between actin and myosin and the length of the sarcomere. Then the video...

Find out how a cell that is permeable to one ion can become charged (either positive or negative) if there is permeability and a concentration gradient. Rishi is a pediatric infectious disease physician and works at Khan Academy. [8:21]

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. [12:02]

Visit us (http://www.khanacademy.org/science/healthcare-and-medicine) for health and medicine content or (http://www.khanacademy.org/test-prep/mcat) for MCAT related content. These videos do not provide medical advice and are for...

Watch as fetal blood goes through umbilical vessels and takes a shortcut through the Ductus Venosus to make it back to the heart. Rishi is a pediatric infectious disease physician and works at Khan Academy.

This video describes how calcium ion concentration dictates whether a muscle contracts or not. [9:22]

Sports physiologists understand the body's anatomy and the biomechanics of how bones and muscles work together. These scientists can help improve athletes' performance and help keep them healthy. But many young athletes are unaware of...

This video will help you 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...

Figure out how all of those physiology terms: end-systolic, end-diastolic, pulse pressure, stroke volume, and ejection fraction, can be easily figured out using the pressure-volume loop. [9:18]

Paul Andersen introduces Anatomy and Physiology in this podcast. He starts by describing how the form of an object fits the function. He then explains the themes of homeostasis and hierarchy. He describes the four major types of tissues;...

This lesson will describe how the differences in concentrations of ions across a plasma membrane set the stage for a nerve impulse. It is 1 of 2 in the series titled "Membrane Potential."