Show an image of the circulatory and respiratory systems.
e.g. https://www.pinterest.ca/pin/843439836446359943/
The respiratory and circulatory systems bring O2 to cells of your body and takes away CO2 waste.
Respiratory system = lungs, mouth and throat. Brings oxygen into the body, and exhales CO2.
Circulatory system = blood vessels, heart which pumps the blood. Brings O2 to cells, removes CO2.
Show a beating heart gif: https://en.wikipedia.org/wiki/Heart#/media/File:CG_Heart.gif
Point out the valves closing one after the other, the 'lub dub' of the beating heart.
Students use stethoscopes to listen to the valves closing in their hearts.
I do not have one stethoscope per student, so they pair up, and one listens to their heart (in the silent classroom), while the other runs around the school/field once (makes the beats stronger and louder, so easier to hear). Switch after 2 mins. Switch a couple of times.
Your heart beats your whole life, pushing blood around your body to bring oxygen to every cell.
Your heart is a piece of muscle (meat). Optionally show images of cow heart.
Students feel their pulse, which is the push of blood in blood vessels with each heartbeat.
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.
The lungs bring oxygen into your body, and exhale carbon dioxide.
Lung model to show how air is drawn into the lungs as the diaphragm muscle contracts.
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.
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.]
