IGCSE Biology - Gas exchange in humans (11.1)

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Cambridge IGCSE Biology (0610/0970)
Chapter 11 - Gas exchange in humans
Topic 11.1 - Gas exchange in humans
For exams in 2023, 2024 & 2025 (core and extended)

As always this video follows the Cambridge syllabus exactly and contains absolutely everything you need to know for your final exam!

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Timestamps:
0:00 Contents
0:43 Structures of the breathing system
1:29 Features of gas exchange surfaces
2:27 Limewater experiment
2:58 Composition of air
3:17 Breathing rate and depth
3:51 Breathing muscles (extended)
4:13 Mechanics of breathing (extended)
5:00 Composition of air (extended)
5:29 Breathing rate and depth (extended)
6:02 Defence mechanisms (extended)

Core content:
- Describe the features of gas exchange surfaces in humans, limited to: large surface area, thin surface, good blood supply and good ventilation with air
- Identify in diagrams and images the following parts of the breathing system: lungs, diaphragm, ribs, intercostal muscles, larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries
- Investigate the differences in composition between inspired and expired air using limewater as a test for carbon dioxide
- Describe the differences in composition between inspired and expired air, limited to: oxygen, carbon dioxide and water vapour
- Investigate and describe the effects of physical activity on the rate and depth of breathing using a spirometer trace

Extended content:
- Identify in diagrams and images the internal and external intercostal muscles
- State the function of cartilage in the trachea
- Explain the role of the ribs, the internal and external intercostal muscles and the diaphragm in producing volume and pressure changes in the thorax leading to the ventilation of the lungs
- Explain the differences in composition between inspired and expired air
- Explain the link between physical activity and the rate and depth of breathing in terms of: an increased carbon dioxide concentration in the blood, which is detected by the brain, leading to an increased rate and greater depth of breathing
- Explain the role of goblet cells, mucus and ciliated cells in protecting the breathing system from pathogens and particles

Context:
- The respiratory or breathing system works in tandem with the heart, blood vessels and blood.
- In chapter 9 we learned about the double circulation system of humans.
- Deoxygenated blood is ejected from the right ventricle and transported to the lungs through the pulmonary artery.
- In the lungs, oxygen diffuses into the bloodstream and carbon dioxide is removed. This is the focal point of this lesson.
- The now oxygenated blood returns to the left atrium in the pulmonary vein.
- The left ventricle then pumps the blood through the aorta to the body's tissues.
- The oxygen is used by cells to produce energy through respiration. Carbon dioxide is released as a byproduct of this process.