Science

• The human respiratory system includes the Nose, Trachea, Lungs, Bronchi, Bronchioles, Alveolus, Intercostal muscles, and Diaphragm.
• Air normally enters the air passages through the nose.
• Fine hairs in the nose trap some of the dust particles in the air.
• The chemical equation for cellular respiration is: Glucose + oxygen  energy + carbon dioxide + water.
• Cell respiration occurs in both plant cells and animal cells.
• Some organisms such as yeast and some bacteria do not use oxygen for respiration and carry out anaerobic respiration.
• Cell respiration that uses oxygen is classified as aerobic respiration.
• The nose is moistened by mucus, a watery liquid, to make the air moist as it passes inwards.
• Mucus traps bacteria that are carried on the air currents.
• The air is warmed by the body temperature.
• The Trachea, or windpipe, is made from rings of cartilage, each ring in the shape of a “C”.
• The inner lining of the windpipe has two types of cells: Mucus-secreting cells to trap the dust particles and bacteria in the form of mucus, and Ciliated epithelial cells, whose cilia move the mucus to the top of the windpipe where it enters the back of the mouth and is swallowed.
• The lungs contain the bronchi and bronchioles, which divide into many smaller tubes called bronchioles.
• After travelling into the many bronchioles, air finally passes into some of the millions of tiny sacs called alveoli, which have the specialised surfaces for gas exchange.
• An alveolus has adaptations to allow it to exchange gases effectively: a large surface area, thin and elastic walls, surrounded by a network of blood capillaries, and a moist surface.
• The chest wall is made by the ribs and intercostal muscles, each rib is attached to the backbone by a joint that allows only a small amount of movement, and the internal and external intercostal muscles make the ribs move.
• The diaphragm is a large sheet of muscle attached to the edges of the tenth pair of ribs and the backbone, it separates the chest cavity (lungs & heart) from the lower body cavity.
• Inhalation is the process of taking air into the lungs.
• Exhalation is the process of expelling air from the lungs.
• Model to show the action of the diaphragm: Plastic Y tube represents trachea and bronchi, Bell jar represents thoracic cavity, Thin rubber sheet represents diaphragm, Balloons represent lungs.
• Carbon dioxide in the body cells diffuses into the blood capillaries during inhalation.
• The blood capillaries now carry deoxygenated blood which is dark/dull red in colour during inhalation.
• Cell Respiration: The process in which food is oxidised in the cells to get energy.