12.2.2

Oxygen Use & Debt

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Anaerobic Respiration

If muscles are not supplied with enough oxygen during long periods of activity (like exercise), then muscle cells may start to respire anaerobically. This can lead to oxygen debt:

Lactic acid

Lactic acid

  • Lactic acid is a by-product of anaerobic respiration.
  • Lactic acid is toxic and can build up in muscles, leading to muscular pain and fatigue.
  • Lactic acid also stops muscles contracting efficiently.
Oxygen debt

Oxygen debt

  • Oxygen debt refers to the extra oxygen required after exercise to oxidise (combine with oxygen) lactic acid and remove it from cells.
Repaying the debt

Repaying the debt

  • Blood transports the lactic acid to the liver, where it reacts with oxygen to produce carbon dioxide and water.
  • Heavy breathing after exercise helps to repay the oxygen debt by taking more oxygen into the lungs for the break-down of lactic acid.
  • A fast heart rate helps transport lactic acid from muscles to the liver.
Jump to other topics
1

Classification of Living Organisms

2

Organisation of the Organism

3

Movement Into & Out of Cells

4

Biological Molecules

5

Enzymes

6

Plant Nutrition

7

Human Nutrition

8

Transport in Plants

9

Transport in Animals

10

Diseases & Immunity

11

Gas Exchange in Humans

12

Respiration

13

Excretion in Humans

14

Coordination & Response

15

Drugs

16

Reproduction

17

Inheritance

18

Variation & Selection

19

Organisms & Their Environment

20

Human Influence on Ecosystems

21

Biotechnology & Genetic Modification

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