Source: https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-1-human-gas-exchange [Revision notes](https://senecalearning.com/en-gb/revision-notes.md) › [BTEC](https://senecalearning.com/en-gb/revision-notes/btec.md) › [Science](https://senecalearning.com/en-gb/revision-notes/btec/science.md) › [Applied Science: BTEC Level 3](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3.md) › Human Gas Exchange # Human Gas Exchange Applied Science: BTEC Level 3 National Extended Diploma, topic 1.5.1 ## Structure Human gas exchange takes place in specialised organs called the lungs. The lungs are specialised for the quick exchange of oxygen and carbon dioxide with the bloodstream. ### Structure ![Structure](https://image-v2.cdn.app.senecalearning.com/courseImages/biology/2.3.2%20-%20The%20heart%20and%20circulatory%20system/Lung%20Structure%20-%20Edited%20(1)-min.png) ### Trachea ![Trachea](https://image-v2.cdn.app.senecalearning.com/2018-09/31b5077c-be37-4429-abf2-8a0bdb1d5be5/lungs-trachea.png) - The trachea is the entrance to the human gas exchange system. - When you breathe in, air flows through the trachea. - Ridges of cartilage surround the front of the trachea to provide protection and structure. - There is no cartilage at the back of the trachea so that the oesophagus (the tube where food travels) is not constricted. ### Bronchi & bronchioles ![Bronchi & bronchioles](https://image-v2.cdn.app.senecalearning.com/2018-09/31b5077c-be37-4429-abf2-8a0bdb1d5be5/lungs-trachea.png) - The trachea divides into two bronchi. - Air flows along each bronchus to a lung. - The bronchi are made from cartilage and smooth muscle. - Each bronchus divides into many smaller bronchioles. - The many bronchioles branch throughout the the lungs into small air-sacs called alveoli. ### Alveoli ![Alveoli](https://image-v2.cdn.app.senecalearning.com/2018-09/31b5077c-be37-4429-abf2-8a0bdb1d5be5/lungs-trachea.png) - The alveoli are sacs that fill with air when you breathe in. - Oxygen in the alveoli diffuses into the bloodstream and carbon dioxide in the bloodstream diffuses into the alveoli. - There are millions of alveoli in the lungs - The alveoli provide a large surface area for gas exchange. ### Control of ventilation ![Control of ventilation](https://image-v2.cdn.app.senecalearning.com/courseImages/biology/2.3.2%20-%20The%20heart%20and%20circulatory%20system/lungs-min.jpg) - Ventilation is controlled by the ribcage, intercostal muscles and the diaphragm. - When you breathe in, these structures move to allow the lungs to fill with air. - When you breathe out, these structures move to allow air to leave the lungs. ### Columnar epithelium ![Columnar epithelium](https://image-v2.cdn.app.senecalearning.com/2018-10/79f407c9-84ce-407b-8705-d5b1dbdd1a11/mass.jpg) - The trachea, bronchi, and large bronchioles are lined with columnar ciliated epithelium. - Goblet cells are the mucus-secreting cells of ciliated epithelium. This mucus traps dust, particles, and pathogens. - Ciliated cells are columnar in shape. They have multiple, thin projections from their surface ('cilia"). - Cilia contract and "waft" the mucus produced by goblet cells up the trachea to the back of the throat, where it is swallowed. - Any swallowed pathogens are destroyed by stomach acid. ## Alveoli Alveoli are the millions of air sacs within the lungs where gases are exchanged with the bloodstream. They provide a large surface area for gas exchange. ### Capillaries ![Capillaries](https://image-v2.cdn.app.senecalearning.com/2018-09/6a902503-11bb-42a9-9a95-bbbdefaadc9f/Alveoli.jpg) - Each alveolus is surrounded by a network of capillaries. - The many capillaries provide a large surface area for gas exchange between the alveoli and the bloodstream. ### Alveolar epithelium ![Alveolar epithelium](https://image-v2.cdn.app.senecalearning.com/2018-09/6e9016b9-a854-4a7f-a50b-640ad495acde/Alveoli.jpg) - The alveolar epithelium is made up of a single layer of squamous epithelial cells that line the walls of the alveoli. - Squamous epithelial cells are generally round, flat, and have a small, centrally located nucleus. - In the alveoli, the squamous cells are arranged in a single layer to facilitate gas diffusion. - The squamous epithelium provides a very short diffusion distance from the alveoli to the capillaries which maximises the rate of gas exchange. ### Concentration gradient ![Concentration gradient](https://image-v2.cdn.app.senecalearning.com/2018-09/eb55149c-7afa-49f2-9d6e-82c07f0bf3f8/concentration-gradient.png) - The capillaries supply carbon dioxide to the alveoli and oxygen is rapidly carried away from the alveoli. - The quick transport of gases in the bloodstream maintains a steep concentration gradient of oxygen and carbon dioxide. - The steep concentration gradient allows quick diffusion of gases into and out of the bloodstream. ## Smoking and the Respiratory System Smoking can causes a range of very serious diseases. Cigarette smoke contains harmful chemical such as nicotine, carbon monoxide and carcinogens (cancer-causing chemicals). ### Bronchitis ![Bronchitis](https://image-v2.cdn.app.senecalearning.com/2018-03/970c6855-ebf7-4453-91d9-ebc0c4de5d67/shutterstock_1017449866.jpg) - When smoke is breathed in, it damages the cilia cells of the airways. - This means the cilia can't waft away the mucus produced by goblet cells, and the mucus builds up. - This can leads to bronchitis, where the airways are partly blocked with mucus. ### Emphysema ![Emphysema](https://image-v2.cdn.app.senecalearning.com/2018-03/e2b27933-3522-429b-9047-3d1f5132e18b/shutterstock_147525569.jpg) - Smoking damages the elastic fibres in the alveoli. This prevents elastic recoil and causes overinnflation of the lungs. - This can cause emphysema, where gas exchange can't happen efficiently, causing shortness of breath. - Together bronchitis and emphysema form a condition called chronic obtrusive pulmonary disease (COPD). - Symptoms include a cough, breathlessness, and wheezing. ### Cancers ![Cancers](https://image-v2.cdn.app.senecalearning.com/2018-03/7863deb6-4898-49f8-a664-5749b47da12f/shutterstock_198678062.jpg) - The carcinogens in the tar in cigarettes can cause tumours to form in the airways. - Smoking can cause mouth, throat and lung cancers. ### Heart disease and strokes ![Heart disease and strokes](https://image-v2.cdn.app.senecalearning.com/2018-03/904d8946-884f-493b-81ee-aeedebc8757e/shutterstock_363299582.jpg) - Nicotine is very addictive and puts strain on the heart. - Nicotine acts as a stimulant and causes the heart to beat faster at with greater force. This can increase blood pressure. - Carbon monoxide reduces the ability of red blood cells to carry oxygen, which can also put strain on the heart. Carbon monoxide binds to haemaglobin with 200x the affinity of oxygen. - Both of these substances can cause heart disease and strokes. ## Test yourself on Human Gas Exchange - Which of these is NOT a structure in the lungs? - Which of the following statements about the lungs are true? - Which of the following statements about alveoli are true? - What is the benefit of the single layer of epithelial cells in the alveoli for gas exchange? - Which disease is not caused by smoking? [Practise this topic for free](https://app.senecalearning.com/classroom/course/83e90d6d-8d3e-4e59-a2df-b5a5e1957f6c/section/943f2d91-0746-44ac-aa00-86022c0f9b43/session) - Previous topic: [1.4.4 Gametes](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-4-4-gametes.md) - Next topic: [1.5.2 Blood Vessels](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-2-blood-vessels.md) ## Applied Science: BTEC Level 3 National Extended Diploma contents ### 1 Principles of Science I - 1.1 Structure & Bonding - [1.1.1 Atomic Model](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-1-atomic-model.md) - [1.1.2 Electron Shells, Sub-Shells & Orbitals](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-2-electron-shells-sub-shells-and-orbitals.md) - [1.1.3 Ionic Bonding](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-3-ionic-bonding.md) - [1.1.4 Representing Ionic Bonds](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-4-representing-ionic-bonds.md) - [1.1.5 Covalent Bonding](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-5-covalent-bonding.md) - [1.1.6 Representing Covalent Bonds](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-6-representing-covalent-bonds.md) - [1.1.7 Metallic Bonding](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-7-metallic-bonding.md) - [1.1.8 Intermolecular Forces](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-8-intermolecular-forces.md) - [1.1.9 Intermolecular Forces 2](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-9-intermolecular-forces-2.md) - [1.1.10 End of Topic Test - Bonding](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-10-end-of-topic-test-bonding.md) - [1.1.11 Relative Masses](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-11-relative-masses.md) - [1.1.12 The Mole](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-12-the-mole.md) - [1.1.13 Molar Calculations](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-13-molar-calculations.md) - [1.1.14 Molar Calculations 2](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-14-molar-calculations-2.md) - [1.1.15 Empirical & Molecular Formulae](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-15-empirical-and-molecular-formulae.md) - [1.1.16 Balanced Equations](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-16-balanced-equations.md) - [1.1.17 Percentage Yield](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-17-percentage-yield.md) - [1.1.18 End of Topic Test - Amount of Substance](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-1-18-end-of-topic-test-amount-of-substance.md) - 1.2 Properties of Substances - [1.2.1 The Periodic Table](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-2-1-the-periodic-table.md) - [1.2.2 Ionisation Energy](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-2-2-ionisation-energy.md) - [1.2.3 Factors Affecting Ionisation Energies](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-2-3-factors-affecting-ionisation-energies.md) - [1.2.4 Trends of Ionisation](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-2-4-trends-of-ionisation.md) - [1.2.5 Trends in the Periodic Table](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-2-5-trends-in-the-periodic-table.md) - [1.2.6 Polarity](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-2-6-polarity.md) - [1.2.7 Metals & Non-Metals](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-2-7-metals-and-non-metals.md) - [1.2.8 Alkali Metals](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-2-8-alkali-metals.md) - [1.2.9 Alkaline Earth Metals](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-2-9-alkaline-earth-metals.md) - [1.2.10 Reactivity of Alkaline Earth Metals](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-2-10-reactivity-of-alkaline-earth-metals.md) - [1.2.11 Redox](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-2-11-redox.md) - [1.2.12 Transition Metals](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-2-12-transition-metals.md) - [1.2.13 Redox Reactions of Transition Metals](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-2-13-redox-reactions-of-transition-metals.md) - 1.3 Cell Structure & Function - [1.3.1 Introduction to Cells](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-3-1-introduction-to-cells.md) - [1.3.2 Prokaryotes](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-3-2-prokaryotes.md) - [1.3.3 Organelles of Eukaryotic Cells](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-3-3-organelles-of-eukaryotic-cells.md) - [1.3.4 Organelles of Eukaryotic Cells 2](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-3-4-organelles-of-eukaryotic-cells-2.md) - [1.3.5 Organelles in Plant Cells](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-3-5-organelles-in-plant-cells.md) - [1.3.6 Microscopy](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-3-6-microscopy.md) - [1.3.7 End of Topic Test - Cell Structure](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-3-7-end-of-topic-test-cell-structure.md) - 1.4 Cell Specialisation - [1.4.1 Cell Specialisation](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-4-1-cell-specialisation.md) - [1.4.2 Blood Cells](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-4-2-blood-cells.md) - [1.4.3 Plant Cells](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-4-3-plant-cells.md) - [1.4.4 Gametes](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-4-4-gametes.md) - 1.5 Tissue Structure & Function - [1.5.1 Human Gas Exchange](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-1-human-gas-exchange.md) - [1.5.2 Blood Vessels](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-2-blood-vessels.md) - [1.5.3 Atherosclerosis](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-3-atherosclerosis.md) - [1.5.4 Skeletal Muscle](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-4-skeletal-muscle.md) - [1.5.5 Slow & Fast Twitch Fibres](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-5-slow-and-fast-twitch-fibres.md) - [1.5.6 Neurones](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-6-neurones.md) - [1.5.7 Speed of Transmission](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-7-speed-of-transmission.md) - [1.5.8 Action Potentials](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-8-action-potentials.md) - [1.5.9 End of Topic Test - Neurones & Action Potentials](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-9-end-of-topic-test-neurones-and-action-potentials.md) - [1.5.10 Synapses](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-10-synapses.md) - [1.5.11 Types of Synapse](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-11-types-of-synapse.md) - [1.5.12 Medical Application](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-12-medical-application.md) - [1.5.13 End of Topic Test - Synapses](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-13-end-of-topic-test-synapses.md) - [1.5.14 Chemical Brain Imbalances](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-14-chemical-brain-imbalances.md) - [1.5.15 Effect of Drugs on the Brain](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-5-15-effect-of-drugs-on-the-brain.md) - 1.6 Working with Waves - [1.6.1 Progressive Waves](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-6-1-progressive-waves.md) - [1.6.2 Wave Speed & Phase Difference](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-6-2-wave-speed-and-phase-difference.md) - [1.6.3 Longitudinal & Transverse Waves](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-6-3-longitudinal-and-transverse-waves.md) - [1.6.4 Stationary Waves](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-6-4-stationary-waves.md) - [1.6.5 Stationary Waves 2](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-6-5-stationary-waves-2.md) - [1.6.6 Applications of Stationary Waves](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-6-6-applications-of-stationary-waves.md) - [1.6.7 Interference](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-6-7-interference.md) - [1.6.8 Diffraction](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-6-8-diffraction.md) - [1.6.9 Diffraction Gratings](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-6-9-diffraction-gratings.md) - [1.6.10 Application of Diffraction Gratings](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-6-10-application-of-diffraction-gratings.md) - 1.7 Waves in Communication - [1.7.1 Refraction at a Plane Surface](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-7-1-refraction-at-a-plane-surface.md) - [1.7.2 Internal Reflection & Fibre Optics](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-7-2-internal-reflection-and-fibre-optics.md) - [1.7.3 Applications of Total Internal Reflection](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-7-3-applications-of-total-internal-reflection.md) - [1.7.4 Properties](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-7-4-properties.md) - [1.7.5 Gamma, X-Ray & UV Light](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-7-5-gamma-x-ray-and-uv-light.md) - [1.7.6 Visible Light](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-7-6-visible-light.md) - [1.7.7 Infrared, Microwave & Radio Waves](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-7-7-infrared-microwave-and-radio-waves.md) - [1.7.8 Intensity](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-7-8-intensity.md) - [1.7.9 Digital & Analogue Signals](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-7-9-digital-and-analogue-signals.md) - [1.7.10 Communication Channels](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/1-7-10-communication-channels.md) ### 2 Practical Scientific Procedures and Techniques - 2.1 Titration - [2.1.1 pH Curves & Titrations](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/2-1-1-ph-curves-and-titrations.md) - [2.1.2 pH Curves & Titrations 2](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/2-1-2-ph-curves-and-titrations-2.md) - [2.1.3 Buffer Solutions](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/2-1-3-buffer-solutions.md) - 2.2 Colorimetry - [2.2.1 Measuring Rates](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/2-2-1-measuring-rates.md) - [2.2.2 Beer-Lambert Law](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/2-2-2-beer-lambert-law.md) - 2.3 Chromatography - [2.3.1 Overview of Chromatography](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/2-3-1-overview-of-chromatography.md) - [2.3.2 Thin-Layer Chromatography](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/2-3-2-thin-layer-chromatography.md) - [2.3.3 Column Chromatography](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/2-3-3-column-chromatography.md) - [2.3.4 Gas Chromatography](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/2-3-4-gas-chromatography.md) ### 3 Science Investigation Skills - 3.1 Scientific Processes - [3.1.1 Aims, Hypotheses & Sampling](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-1-1-aims-hypotheses-and-sampling.md) - [3.1.2 Pilot Studies & Design](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-1-2-pilot-studies-and-design.md) - [3.1.3 Ethics](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-1-3-ethics.md) - [3.1.4 Variables & Control](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-1-4-variables-and-control.md) - [3.1.5 Demand Characteristics & Investigator Effects](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-1-5-demand-characteristics-and-investigator-effects.md) - [3.1.6 Features of Science](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-1-6-features-of-science.md) - [3.1.7 Scientific Report](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-1-7-scientific-report.md) - [3.1.8 Scientific Report 2](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-1-8-scientific-report-2.md) - 3.2 Data Handling & Analysis - [3.2.1 Types of Data](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-2-1-types-of-data.md) - [3.2.2 Descriptive Statistics](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-2-2-descriptive-statistics.md) - [3.2.3 Presentation & Display of Data](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-2-3-presentation-and-display-of-data.md) - 3.3 Enzymes in Action - [3.3.1 Overview of Protein Structure](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-3-1-overview-of-protein-structure.md) - [3.3.2 Enzymes](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-3-2-enzymes.md) - [3.3.3 Factors Affecting Enzyme Activity](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-3-3-factors-affecting-enzyme-activity.md) - [3.3.4 Enzyme-Controlled Reactions](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-3-4-enzyme-controlled-reactions.md) - 3.4 Diffusion - [3.4.1 Diffusion](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-4-1-diffusion.md) - 3.5 Plants & Their Environment - [3.5.1 Factors Affecting Plant Growth](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-5-1-factors-affecting-plant-growth.md) - [3.5.2 Measuring Number & Distribution of Species](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-5-2-measuring-number-and-distribution-of-species.md) - 3.6 Energy Content in Fuels - [3.6.1 Fractions](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-6-1-fractions.md) - [3.6.2 Burning Hydrocarbons](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-6-2-burning-hydrocarbons.md) - [3.6.3 Combustion](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-6-3-combustion.md) - [3.6.4 Energy](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-6-4-energy.md) - [3.6.5 Energy at Home](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-6-5-energy-at-home.md) - [3.6.6 Calorimetry](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-6-6-calorimetry.md) - 3.7 Electrical Circuits - [3.7.1 Circuit Diagrams & Components](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-7-1-circuit-diagrams-and-components.md) - [3.7.2 Diodes, LDRs & Thermistors](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-7-2-diodes-ldrs-and-thermistors.md) - [3.7.3 Resistance](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-7-3-resistance.md) - [3.7.4 Electrical Work](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-7-4-electrical-work.md) - [3.7.5 Ohm's Law](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-7-5-ohms-law.md) - [3.7.6 Domestic Uses of Electricity](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-7-6-domestic-uses-of-electricity.md) - [3.7.7 Fuses](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/3-7-7-fuses.md) ### 4 Principles of Science II - 4.1 Extracting Elements - [4.1.1 Atom Economy](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-1-1-atom-economy.md) - 4.2 Relating Properties to use of Substances - [4.2.1 Group 2 Chemistry](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-2-1-group-2-chemistry.md) - [4.2.2 End of Topic Test - Group 2](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-2-2-end-of-topic-test-group-2.md) - [4.2.3 Electrolysis](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-2-3-electrolysis.md) - [4.2.4 Electrolysis Examples](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-2-4-electrolysis-examples.md) - [4.2.5 Extracting Metals](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-2-5-extracting-metals.md) - [4.2.6 Transition Metals](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-2-6-transition-metals.md) - [4.2.7 Variable Oxidation States](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-2-7-variable-oxidation-states.md) - [4.2.8 Heterogeneous Catalysts](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-2-8-heterogeneous-catalysts.md) - [4.2.9 Homogeneous Catalysts](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-2-9-homogeneous-catalysts.md) - 4.3 Organic Chemistry - [4.3.1 Naming Compounds](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-3-1-naming-compounds.md) - [4.3.2 Functional Groups](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-3-2-functional-groups.md) - [4.3.3 Isomerism](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-3-3-isomerism.md) - [4.3.4 Hydrocarbons](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-3-4-hydrocarbons.md) - [4.3.5 Structure of Alkanes](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-3-5-structure-of-alkanes.md) - [4.3.6 Boiling Points of Alkanes](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-3-6-boiling-points-of-alkanes.md) - [4.3.7 Alkenes](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-3-7-alkenes.md) - [4.3.8 Curly Arrows & Mechanisms](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-3-8-curly-arrows-and-mechanisms.md) - [4.3.9 Cracking](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-3-9-cracking.md) - [4.3.10 Combustion](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-3-10-combustion.md) - [4.3.11 Free Radical Substitution of Alkanes](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-3-11-free-radical-substitution-of-alkanes.md) - [4.3.12 Electrophilic Addition of Alkenes](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-3-12-electrophilic-addition-of-alkenes.md) - 4.4 Energy Changes in Industry - [4.4.1 The Kelvin Scale](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-4-1-the-kelvin-scale.md) - [4.4.2 Enthalpy Changes](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-4-2-enthalpy-changes.md) - [4.4.3 Calorimetry](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-4-3-calorimetry.md) - [4.4.4 Bond Enthalpies](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-4-4-bond-enthalpies.md) - [4.4.5 Hess' Law](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-4-5-hess-law.md) - 4.5 The Circulatory System - [4.5.1 The Circulatory System](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-5-1-the-circulatory-system.md) - [4.5.2 Blood Vessels](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-5-2-blood-vessels.md) - [4.5.3 Blood Transfusion & the ABO Rhesus System](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-5-3-blood-transfusion-and-the-abo-rhesus-system.md) - [4.5.4 The Heart](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-5-4-the-heart.md) - [4.5.5 The Cardiac Cycle](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-5-5-the-cardiac-cycle.md) - [4.5.6 Cardiac Output](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-5-6-cardiac-output.md) - [4.5.7 Coordination of Heart Action](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-5-7-coordination-of-heart-action.md) - [4.5.8 Heart Dissection](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-5-8-heart-dissection.md) - [4.5.9 Controlling Heart Rate](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-5-9-controlling-heart-rate.md) - [4.5.10 Electrocardiograms](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-5-10-electrocardiograms.md) - [4.5.11 Cardiovascular Disease](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-5-11-cardiovascular-disease.md) - [4.5.12 Investigating Heart Rates](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-5-12-investigating-heart-rates.md) - 4.6 Ventilation & Gas Exchange - [4.6.1 Human Gas Exchange](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-6-1-human-gas-exchange.md) - [4.6.2 Ventilation](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-6-2-ventilation.md) - [4.6.3 Measuring Gas Exchange](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-6-3-measuring-gas-exchange.md) - [4.6.4 Controlling Ventilation Rate](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-6-4-controlling-ventilation-rate.md) - [4.6.5 Lung Disease](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-6-5-lung-disease.md) - [4.6.6 Lung Disease Data](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-6-6-lung-disease-data.md) - 4.7 Urinary System - [4.7.1 Kidneys & Control of Water Balance](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-7-1-kidneys-and-control-of-water-balance.md) - [4.7.2 Kidneys & Osmoregulation](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-7-2-kidneys-and-osmoregulation.md) - [4.7.3 Kidneys & Blood Pressure](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-7-3-kidneys-and-blood-pressure.md) - [4.7.4 Urine](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-7-4-urine.md) - [4.7.5 Kidney Failure & Urinalysis](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-7-5-kidney-failure-and-urinalysis.md) - [4.7.6 Dialysis](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-7-6-dialysis.md) - [4.7.7 Transplants](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-7-7-transplants.md) - 4.8 Cell Transport - [4.8.1 Cell Membrane Structure](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-8-1-cell-membrane-structure.md) - [4.8.2 Diffusion](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-8-2-diffusion.md) - [4.8.3 Osmosis](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-8-3-osmosis.md) - [4.8.4 Active Transport](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-8-4-active-transport.md) - 4.9 Thermal Physics - [4.9.1 Power & Efficiency](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-9-1-power-and-efficiency.md) - [4.9.2 Work & Energy](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-9-2-work-and-energy.md) - [4.9.3 Conservation of Energy](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-9-3-conservation-of-energy.md) - [4.9.4 Pressure](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-9-4-pressure.md) - [4.9.5 First Law of Thermodynamics](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-9-5-first-law-of-thermodynamics.md) - [4.9.6 Second Law of Thermodynamics](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-9-6-second-law-of-thermodynamics.md) - [4.9.7 Heat Engines, Heat Pumps & Refrigerators](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-9-7-heat-engines-heat-pumps-and-refrigerators.md) - [4.9.8 Non-Flow Processes](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-9-8-non-flow-processes.md) - [4.9.9 p-V Diagrams](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-9-9-p-v-diagrams.md) - [4.9.10 Ideal Gases](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-9-10-ideal-gases.md) - [4.9.11 Ideal Gases 2](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-9-11-ideal-gases-2.md) - [4.9.12 Thermal Energy Transfer](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-9-12-thermal-energy-transfer.md) - [4.9.13 Thermal Energy Transfer Experiments](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-9-13-thermal-energy-transfer-experiments.md) - 4.10 Materials - [4.10.1 Density](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-10-1-density.md) - [4.10.2 Stress & Strain](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-10-2-stress-and-strain.md) - [4.10.3 Properties of Materials](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-10-3-properties-of-materials.md) - [4.10.4 Elasticity](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-10-4-elasticity.md) - [4.10.5 Plasticity](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-10-5-plasticity.md) - [4.10.6 Energy in Materials](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-10-6-energy-in-materials.md) - [4.10.7 Young Modulus](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-10-7-young-modulus.md) - 4.11 Fluids - [4.11.1 Fluid Flow](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-11-1-fluid-flow.md) - [4.11.2 Viscosity](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-11-2-viscosity.md) - [4.11.3 Density](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-11-3-density.md) - [4.11.4 Continuity Equation](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-11-4-continuity-equation.md) - [4.11.5 Bernoulli's Equation](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-11-5-bernoullis-equation.md) - [4.11.6 Non-Newtonian Fluids](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/4-11-6-non-newtonian-fluids.md) ### 5 Contemporary Issues in Science - 5.1 Contemporary Issues in Science - [5.1.1 Sustainability](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/5-1-1-sustainability.md) - [5.1.2 Genetic Engineering](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/5-1-2-genetic-engineering.md) - [5.1.3 Uses of Genetic Modification](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/5-1-3-uses-of-genetic-modification.md) - [5.1.4 Stem Cell Therapy](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/5-1-4-stem-cell-therapy.md) - [5.1.5 Cloning](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/5-1-5-cloning.md) - [5.1.6 Cloning 2](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/5-1-6-cloning-2.md) - [5.1.7 Nanotechnology](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/5-1-7-nanotechnology.md) - [5.1.8 Ecosystems](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/5-1-8-ecosystems.md) - 5.2 Analysing Scientific Information - [5.2.1 Validity](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/5-2-1-validity.md) - [5.2.2 Peer Review](https://senecalearning.com/en-gb/revision-notes/btec/science/applied-science-btec-level-3/5-2-2-peer-review.md)