AQA Biology 4.4.2.2

Response to exercise

Run, stop, recover. Watch heart and breathing rates change, and find out why you keep panting after you stop.

Triple Science · Higher tier

Start here

Running for the bus.

You sprint for a bus and just make it. You sit down.

If you had to guess, does your breathing go back to normal straight away, or do you keep breathing hard for a while?

Rest, exercise, recovery

During exercise the human body reacts to the increased demand for energy. Step through the run.

At rest, heart rate and breathing rate are low and steady.

When oxygen runs short

Compare the oxygen your muscles need with the oxygen your blood can deliver.

The heart and lungs keep up: enough oxygen reaches the muscles for aerobic respiration.

During long periods of vigorous activity, muscles become fatigued and stop contracting efficiently.

Higher

Oxygen debt and the liver

Blood flowing through the muscles transports the lactic acid to the liver, where it is converted back into glucose.

Oxygen debt is the amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells.

Anaerobic respiration itself: in Anaerobic respiration.

Think again · what changes?

“Breathing faster is all that changes.”

Your call

Choose

During exercise, which of these increase?

Sort

Place each change.

Tap a card, then tap the box it belongs in. Tap a placed card to take it back.

Command words in this lesson

Key fact

Exercise raises heart rate, breathing rate and breath volume. Short of oxygen, muscles make lactic acid, creating an oxygen debt.

Key note · AQA 4.4.2.2

During exercise, heart rate, breathing rate and breath volume increase to supply the muscles with more oxygenated blood.
If insufficient oxygen is supplied, muscles respire anaerobically. Incomplete oxidation of glucose causes a build-up of lactic acid and creates an oxygen debt.
During long periods of vigorous activity muscles become fatigued and stop contracting efficiently.
Higher: blood carries lactic acid to the liver, where it is converted back into glucose. Oxygen debt is the extra oxygen needed after exercise to react with the lactic acid and remove it from the cells.

Photograph this card. Tomorrow, cover it and say each line first.

Not sure what the oxygen debt is?

Heart-rate and breathing-rate curves are made-up teaching data.