B6 Respiration 6.2 Gas Exchange

Identify and label the parts of the respiratory system

Identify and label the parts of the respiratory system nose mouth pharynx larynx Bronchus (bronchi) trachea plural membrane rib lung intercostal muscle Alveolus (alveoli) bronchiole diaphragm

Gas exchange Occurs at alveoli Oxygen diffuses into capillaries Carbon dioxide diffuses out of capillaries Occurs at cells Oxygen diffuses into cells Carbon dioxide diffuses into capillaries Copy into your books the diagram on p121

Red blood cells in an alvelous Alveolar circulation

Features of gas exchange surfaces Gas exchange surfaces in animals have features that make them more efficient: Large surface area Moist surface so gases will dissolve Walls that are only 1 cell thick to reduce diffusion distance A good blood supply to maintain concentration gradient.

Click on the “Passage of air” buttons

The mechanics of breathing Inhalation Exhalation Intercostal muscles contract relax Diaphragm contracts relaxes Volume of thorax increases decreases Pressure in thorax Effect air is pulled in air is pushed out Respiratory system

Comparing inhaled and exhaled air What are the differences between inhaled and exhaled air? inhaled air nitrogen (78%) oxygen (21%) carbon dioxide (0.04%) other exhaled air nitrogen (78%) oxygen (17%) carbon dioxide (4%) other Copy in the table on p120 to show the different compositions.

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Mucous and cilia The cells lining the nose and trachea are designed to trap dust and bacteria.   trachea ciliated epithelial cells

Ciliated epithelial cells The cells that line the wall of the trachea show two special adaptations. produce a sticky liquid - mucous tiny hairs called cilia Ciliated epithelial cells We say the cells show specialisation. These specialised cells have a particular job to do.

The presence of mucus and cilia on the lining of the trachea ensures that the air we breathe is clean and free from disease. ciliated cells mucus being made by the ciliated cells microbes travelling down the trachea within inhaled air microbes become stuck within the mucus Mucus cells and cilia

Tobacco Tobacco comes from the Americas and was introduced to the rest of the world by traders. Can be taken in the form of cigarettes, cigars, pipes and chewing tobacco. The tobacco plant is called Nicotiana tobacca

Tobacco The plant makes an insecticide called nicotine Nicotine acts as an addictive drug in our body in the blood stream, nicotine acts as a stimulant to make the heart beat faster and the small arteries narrow – thus increasing blood pressure. nicotine increases the stickiness of blood platelets Use p164-165 to describe the effects of the other components of smoke on our bodies: Tar Carbon monoxide Smoke particles

Effects of smoking Second hand smoke Effects of smoking The chemicals in tobacco smoke have effects on the heart, circulatory system and the respiratory system. Hot tobacco smoke can irritate the mucus-producing cells and cause cilia to stop beating: Chronic bronchitis is caused when bacteria-filled phlegm (mucus) blocks the bronchi, making it harder to breathe. “smoker’s cough” to help move the phlegm out Emphysema is when the walls of the alveoli break down, reducing the surface area for gas exchange making people gasp for breath Nicotine causes platelets to become stickier, trapping fatty deposits in blood vessels. This narrows the vessel walls and can cause heart disease. Tar in tobacco smoke is carcinogenic, causing cancer. The most common cancer in smokers is lung cancer. Cancer is when body cells begin to grow out of control.