1. Circulation and Exercise

2. How well does your heart pump?
Heart Rate (HR) – number of times the heart beats per minute (bpm)
Stroke Volume (SV) – the amount of blood that leaves a ventricle each time the heart beats.
Cardiac Output (CO) – the amount of blood that leaves the left ventricle in one minute, to be pumped around the body.
CO = SV X HR

3. How to measure heart rate
Carotid artery – in your neck. It is in the groove in your neck beside your windpipe.
Radial artery – in your wrist, below your thumb.

4. WORKSHEET

5. How the body changes during exercise
1 – Cell respiration increases so more CO2 is produced.
2 – Brain detects this and tells your lungs to breathe faster and deeper.
3 – Gas exchange in the capillaries speeds up.
4 – You heart is told to beat faster.
5 – Muscles squeeze on veins, sending more blood back to the heart. Stroke volume increases.
6 – More blood gets pumped out by the heart. Cardiac output increases.

6. 7 – This means more O2 reaches the muscles and more CO2 is carried away per minute.
8 – Arterioles widen to reduce blood pressure.
9 – Blood gets moved to where it is needed.
10 – You get hot. Blood is shunted nearer the skin to cool you down. This is why you o red.
11 – You sweat, which cools you down by evaporation.