Gas Exchange, Respiration and blood

• Gas exchange system is necessary for respiration, which involves chemical reactions in cells breaking down nutrient molecules to release energy for metabolism
• In humans, the nutrient molecule used during respiration is glucose, which is broken down completely in the presence of oxygen through aerobic respiration
• Anaerobic respiration occurs without oxygen, leading to the partial breakdown of glucose and less energy released from one glucose molecule
• During aerobic respiration, carbon dioxide is produced and must be removed from the body to prevent toxic build-up in the cells
• An efficient gas exchange system features a thin surface, good blood supply, good ventilation, and moisture
• Structures in the human gas exchange system include the nasal and oral cavities, trachea (windpipe), bronchi, bronchioles, alveoli, lungs, diaphragm, and thorax (chest cavity)
• Alveoli are important adaptations of the lungs, providing a larger surface area for gaseous exchange, surrounded by a heavy network of capillaries, with walls that are only one-cell thick for efficient gas exchange
• Oxygen diffuses from the alveoli into the blood in the capillaries, binds with haemoglobin in red blood cells, while carbon dioxide in the blood diffuses out of the capillary into the alveoli for removal
• Blood arriving at the capillaries surrounding the alveoli has a low concentration of oxygen and a high concentration of carbon dioxide
• Diffusion is the process where a substance spreads out from a region of higher concentration to a region of lower concentration
• Respiration involves chemical reactions breaking down nutrient molecules in cells to release energy, necessary for various functions in the body
• Aerobic respiration occurs in the mitochondria, gradually releasing energy from glucose based on the cell's needs, with oxygen being chemically combined with glucose to release energy
• Blood is the liquid that transports substances around the body within blood vessels, delivering nutrients, gases, and removing waste products from cells
• Blood consists of red blood cells, white blood cells (including lymphocytes and phagocytes), plasma, and platelets, each with specific functions in the body
• Red blood cells transport oxygen, have haemoglobin, lack a nucleus and mitochondria, and are crucial for oxygen delivery to tissues
• White blood cells, including lymphocytes and phagocytes, protect the body from infections and pathogens through various immune responses
• Plasma is the liquid part of blood, transporting dissolved substances like nutrients, gases, hormones, enzymes, and waste products, while also aiding in heat distribution
• Platelets are tiny cell fragments that help in blood clotting by forming temporary plugs at sites of injury and releasing molecules and enzymes to aid in the clotting process