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Blood Pressure

8 videos
Using the stethoscope to check blood pressure is a technique that’s been used for >100 years! Blood pressure is one of the major vital signs frequently measured by health care workers, and it tells us a lot about our blood circulation. Learn what blood pressure is, how it relates to resistance in a tube, why it is necessary to get oxygen to your cells, and how it can change as you age. We’ll finally put it all together by relating pressure, flow, and resistance in one awesome equation!

What is blood pressure?

VIDEO 6:21 minutes
Find out what a systolic and diastolic blood pressure mean. Rishi is a pediatric infectious disease physician and works at Khan Academy.

Learn how a stethoscope can help determine blood pressure

VIDEO 5:27 minutes
Learn how Dr. Korotkoff cleverly used a stethoscope to determine blood pressure, and that we still use his trick today! Rishi is a pediatric infectious disease physician and works at Khan Academy.

Resistance in a tube

VIDEO 8:54 minutes
Learn how the size of a tube (it's radius) is related to its resistance to something flowing through. Rishi is a pediatric infectious disease physician and works at Khan Academy.

Adding up resistance in series and in parallel

VIDEO 10:33 minutes
Learn about how resistance can be added up in series and in parallel (similar to electrical circuits!). Rishi is a pediatric infectious disease physician and works at Khan Academy.

Adding up resistance problem

VIDEO 3:23 minutes
Here's a chance to see if you can combine what you know to add up resistance in series AND in parallel. Rishi is a pediatric infectious disease physician and works at Khan Academy.

Flow and perfusion

VIDEO 10:31 minutes
Learn the difference between blood flow (Volume/time) and perfusion (Volume/time/amount of tissue). Rishi is a pediatric infectious disease physician and works at Khan Academy.

Putting it all together: Pressure, flow, and resistance

VIDEO 11:50 minutes
See how pressure, flow, and resistance relate to one another and how they each affect the human body. Rishi is a pediatric infectious disease physician and works at Khan Academy.

Blood pressure changes over time

VIDEO 11:25 minutes
See how increasing resistance in the blood vessels can cause blood pressure to rise over time. Rishi is a pediatric infectious disease physician and works at Khan Academy.