Circulation and Exercise

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

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.

WORKSHEET

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.

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.