Introduction

How long can you hold your breath under water?

We breathe because our cells need oxygen and need to get rid of carbon dioxide. When people hold their breath, they are unable to inhale oxygen or exhale the carbon dioxide. This is not a problem for short periods of time. Most people can hold their breath for 30-40 seconds, but the record holder is 24 minutes by a trained free diver, and this is recorded in the Guinness World Records.

As you hold your breath, oxygen levels decrease and carbon dioxide levels increase. This can cause the body's acid-base balance to teeter towards a lower pH (homeostatic level is 7.35-7.45). Cellular activities do not function well when the pH gets below 7.35.

But, don't worry! If you hold your breath too long, you would pass out, and then begin breathing again. Let's take a look at the respiratory structures involved in maintaining this homeostasis.

 

Lesson Objectives

Following successful completion of this lesson, students will be able to...

  • List the general function of the respiratory system.

Enduring Understandings

  • The organs of the respiratory system move air in and out for gas exchange.
  • The respiratory system maintains homeostatic levels of gases and blood pH within the body.

The above objectives correspond with the Alabama Course of Study: Anatomy and Physiology standards: 9

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