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11 videos
Your heart relies on the flow of electricity to maintain a steady, consistent beat - like an automatic pump that maintains a regular rate and rhythm throughout your life! There are specialized heart cells that allow positive current to travel quickly throughout the heart muscle. In these videos, we’ll check out the flow of this positive charge on a macroscopic and microscopic level.

Membrane potentials - part 1

VIDEO 8:22 minutes
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.

Membrane potentials - part 2

VIDEO 8:45 minutes
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.

Permeability and membrane potentials

VIDEO 12:42 minutes
Find out why a cell that is permeable to multiple ions has a membrane potential that is influenced by the ion with the highest permeability. Rishi is a pediatric infectious disease physician and works at Khan Academy.

Action potentials in pacemaker cells

VIDEO 15:40 minutes
Find out how the pacemaker cells use the movement of sodium, calcium, and potassium to get your heart beating! Rishi is a pediatric infectious disease physician and works at Khan Academy.

Action potentials in cardiac myocytes

VIDEO 12:11 minutes
See how muscle cells in the heart contract by allowing Calcium to flow inside and bringing along some positive charge with it! Rishi is a pediatric infectious disease physician and works at Khan Academy.

Resetting cardiac concentration gradients

VIDEO 14:58 minutes
Watch as the heart cells use energy to reset the concentration gradients for all of the ions after the action potential has gone through. Rishi is a pediatric infectious disease physician and works at Khan Academy.

Electrical system of the heart

VIDEO 9:43 minutes
See where the pacemaker cells start the electrical wave of depolarization, and how it gets all the way to the ventricles of the heart. Rishi is a pediatric infectious disease physician and works at Khan Academy.

Depolarization waves flowing through the heart

VIDEO 11:44 minutes
Get a clearer idea of what a "Depolarization Wave" means and how it goes from cell to cell through the entire heart! Rishi is a pediatric infectious disease physician and works at Khan Academy.

A race to keep pace!

VIDEO 13:25 minutes
Find out how the various pacemaker cells in the heart actually race against the clock to try to keep pace for the heart, and how the heart has not one but two back up systems! Rishi is a pediatric infectious disease physician and works at ...

Thinking about heartbeats

VIDEO 9:30 minutes
Find out what happens when things move very slowly through the AV Node! Rishi is a pediatric infectious disease physician and works at Khan Academy.

New perspective on the heart

VIDEO 8:52 minutes
Take a look at the heart in cross section, looking down at it from the top! Rishi is a pediatric infectious disease physician and works at Khan Academy.