Biology: Circulation, Respiration, and Excretion

This week we did the heart and circulation in one class and respiration and excretion in the other.  For my students who took anatomy and physiology two years ago, it was a quick review, and for the rest, it was a quick intro.

The fun thing about biology as a general course is that it's a wild ride across all aspects of biology: dipping your toes into the great stream of life!

One thing the kids found very interesting was comparing their heart rates to the heart rates of a gerbil. Yes, Leena's gerbils are now very tame: stranger with a stethoscope? No problem!

They had guessed that larger animals would have faster heart rates because thy have to push their blood so much farther.  Actually, the opposite is true: because of the law of cubes, larger hearts push much more blood, and therefore don't need to beat as often.

 We also had fun with the blood pressure monitor.  You know how you're supposed to take your blood pressure only after you are resting and still?  What happens when you take your blood pressure while you are trying to pick up something heavy?  After jumping jacks?  When you stand up quickly?

We also had a good time with respiration.  I think I've shown how to do this lung model before, but it's a great way to show how our lungs work on air pressure.

We also used a finger gauge to look at how oxygenated our blood was when we held our breath.  They were surprised: our bodies really don't want to let our oxygen levels drop very much at all!

Of course we've been using Just Bob (our anatomical model) to look at all these body systems.

We also talked kidneys, and our secondary excretory system, the skin.  I used a little hand sanitizer (alcohol) to illustrate evaporative cooling.  Cool!