Respiratory and Circulatory Systems

I do two stations as I do not have one stethoscope per student.
Show gifs of both lung breathing and heart beating when briefing each station.
Station 1:
Lung model to show how air is drawn into our lungs as the diaphragm muscle contracts.
gif: https://upload.wikimedia.org/wikipedia/commons/9/9c/Diaphragmatic_breat… (although the same molecules are not breathed in and out)
Station2:
Stethoscope to listen to the valves closing in your heart.
gif: https://en.wikipedia.org/wiki/Heart#/media/File:CG_Heart.gif

Review the stations, then show how the lungs and heart are connected with a respiratory and circulatory system diagram
e.g. https://www.pinterest.ca/pin/843439836446359943/

Breathing and heart rate before/after exercise activity:
Standing up, quiet in class, close eyes - listen to your own breathing. Feel your heartbeat if you can.
Exercise hard for 30 seconds (start clock when every student has started up). Go hard running on the spot.
Count down to standing still again. Close eyes.
What do you notice about changes in your breathing and heart? (see students' list in photo)
Breathing is deeper and faster. Might also notice your heart beating harder and faster.
When you exercise, your breathing rate and depth increases, and your heart beat gets stronger and speeds up. It is all automatic (you don’t think about it to make it happen).
When you work hard, your cells work hard - they use up more oxygen and release more CO2.
Your brainstem detects the increased CO2 in your blood, and signals your heart rate to increase and your breathing to become deeper.

Optional: activity to show what happens to the blood when CO2 increases: carbon dioxide acidifies water [blood] - the brainstem measures the acidity of the blood and so can sense when CO2 in the blood rises.

When the brainstem detects increased CO2 in the blood, it signals the heart to pump harder and faster, and the breathing to become deeper. This is an automatic response which happens unconsciously. We do not have to think about it.
Deeper breathing means extra oxygen is brought into the body and taken up by the blood. And also more CO2 is exhaled from the body.
Harder and faster heart beats mean more blood is brought to the lungs, to pick up more oxygen, and get it to the cells. And more CO2 is removed.
Refer to the respiratory and circulatory system diagram, working as a system of parts (heart, lungs and blood vessels).

(You can use the cortex of your brain to override and slow down breathing by thinking about it.)

Find your blood
Now that you have looked at models of blood, let's look at the real thing that transports oxygen from your lungs to all fo your cells.
Find places that you can see your own blood.
Distribute flashlight to students, so that they can shine it through their skin and find the red of blood.
[Wrist, under tongue, eyeballs the blood is easily visible. Flashlight through closed fingers.]

If time:
Pulse
Use two flat fingers to feel for it.
Radial pulse - on the wrist just below the thumb (pulse in the radial artery).
Carotid pulse - on the side of the neck under the jaw bone. (One of the strongest pulses as it is close to the heart. The carotid artery supplies blood to the brain.

Calculate how many times your heart beats in your lifetime. Count 15 seconds.
(mine: 64 beats/minute = 30 thousand/year (more when I exercise) = 3 billion (^9) in a lifetime to 90).
This is an underestimate as it beats faster when you exercise.