‘Hitting the Wall’

• What is it?

• Why do you think it happens?

carbondioxideglucose oxygen water

carbondioxide

wateroxygenglucose

energy

energy

Aerobic Respiratio

n Reminder

During anaerobic respiration, glucose breaks down into a substance called lactic acid and some energy is released.

lacticacid energyglucose

anaerobic = ‘without oxygen’

Anaerobic respiration involves the incomplete breakdown of glucose and so releases less energy than aerobic respiration.

Anaerobic respiration is useful to the body when energy is needed in a hurry.

There are two problems with anaerobic respiration:

Anaerobic respiration releases much less energy from glucose compared to aerobic respiration.

Lactic acid is a poisonous waste product.

Why is anaerobic respiration not the best way to get energy from glucose?

lacticacidglucose energy

During aerobic respiration, muscles get energy from glucose by ‘paying’ for it with oxygen.

During anaerobic respiration, muscles get energy from glucose but do not ‘pay’ for it with oxygen.

carbondioxideglucose oxygen water energy

lacticacidglucose energy

When and how is this EPOC ‘paid off’?

This means that an oxygen debt or Excess post-exercise oxygen consumption (EPOC)is created.

Advantages of Anaerobic Respiration

• Anaerobic respiration is useful for muscle cells because it can release energy to allow muscles to contract when the heart and lungs cannot deliver oxygen and glucose fast enough.

Disadvantages of Anaerobic Respiration

• Anaerobic respiration releases much less energy from each molecule of glucose than anaerobic respiration.

• Lactic acid is not removed from the body. It builds up in muscle and blood, and must be broken down after exercise.

The amount of blood circulated by the heart depends on the

heart rate and volume of blood pumped in each beat (stroke

volume)

cardiac output = stroke volume x heart rate

The cardiac output - volume of blood circulated by the

heart in a given time

Cardiac Output Stroke Volume Heart Rate52 6745 7232 7674 5425 5837 7812 92

Calculate the Cardiac Output...

Questions- Progress checkQuestions- Progress check1. When someone is jogging they respire .................... (D)2. But when someone starts to sprint they start to

respire .................... (C)3. Why do they have to respire anaerobically? (C)4. Respiring anaerobically means .................... is made. This can

cause the person to get cramp (C)5. When they stop exercising their breathing does not return to

normal because they need .................... from the air to combine with the lactic acid to get rid of it. (B)

6. Aerobic is more beneficial as it produces ________ energy than anaerobic respiration. (B)

7. What is the term used to describe the process where your body is “owed” oxygen? (A)

Answers

1. Aerobically2. Anaerobically3. Not receiving enough oxygen, so have to use

glucose directly to make energy (respire) without oxygen.

4. Lactic Acid 5. Oxygen6. More7. Excess post-exercise oxygen consumption