Exchange of substances

• Alveoli: Small air sacs found in the lungs at the end of bronchioles which provide a large surface area for gas exchange.
• Antiporter: A membrane protein involved in the cotransport of molecules in opposite directions.
• Atrium: A type of chamber in the heart which receives blood directly from a vein and passes it on to a ventricle.
• Bile salts: Molecules found in the small intestine that assist in the coagulation of lipids, increasing the lipid surface area for breakdown.
• Capillary: A very small blood vessel with thin walls and a small diameter used for substance exchange in tissues.
• Co-transport - A type of membrane transport mechanism involving two different molecules moving across a cell membrane.
• Diaphragm: A large sheet of muscle below the lungs used to reduce and increase the lung capacity to create pressure changes necessary for ventilation.
• Endopeptidase: A class of enzymes that hydrolyze peptide bonds within polypeptides.
• Exopeptidases: A class of enzymes that hydrolyze peptide bonds at the end of proteins (e.g. between the penultimate and last amino acid in the polypeptide).
• External intercostal muscles - A set of muscles found between the ribs on the outside that are involved in forced and quiet inhalation.
• Gill filaments: Small divisions of the gills in fish that extend off the gill arch.
• Gill lamellae: Small protrusions on the gill filaments designed to increase the surface area available for gas exchange.
• Haemoglobin: A protein found in red blood cells that has a quaternary structure and is specialised to carry oxygen to the tissues.
• Internal intercostal muscles - A set of muscles found between the ribs on the inside that are involved in forced exhalation.
• Left atrium: The chamber in the heart that receives oxygenated blood from the pulmonary vein and passes it on to the left ventricle.
• Left ventricle: The chamber in the heart that receives oxygenated blood from the left atrium and pumps it out of the heart to the rest of the body.
• Membrane-bound disaccharidases: A class of enzymes found within membranes that hydrolyze disaccharides into monosaccharides.
• Micelles: An organised group of lipid molecules that aggregate together to provide a hydrophobic capsule for the uptake of lipids.
• Positive cooperativity: Conformational changes caused by the binding of oxygen to haemoglobin that increase the ability of haemoglobin to bind more oxygen.
• Pulmonary vein: The main vein that carries oxygenated blood away from the lungs and back to the heart.
• Renal artery: The main artery that carries oxygenated blood to the kidneys from the heart.
• Renal vein: The main vein that carries deoxygenated blood away from the kidneys back to the heart.
• Right atrium: The chamber in the heart that receives deoxygenated blood directly from the vena cava and passes it on to the right ventricle.
• Right ventricle: The chamber in the heart that receives deoxygenated blood from the right atrium and pumps it out of the heart to the lungs for reoxygenation.
• Spiracles: Small openings on the surface of insects that allow for the exchange of gases with their environment.
• Spongy mesophyll: A type of loosely packed mesophyll tissue with air pockets found in plant leaves which is specialised for gas exchange.
• Stomata: Small holes found on leaves that can be opened or closed by guard cells to control the amount of water loss and gas exchange.
• The Bohr effect: A decrease in the affinity of haemoglobin for oxygen in areas with a high carbon dioxide concentration.
• Tissue fluid: Fluid filtered out from the blood that bathes tissues and provides the cells with substances like food and dissolved gases for exchange.
• Trachea (mammals): A tube reinforced with cartilage that allows for the movement of air between the larynx and bronchi.
• Tracheae (insects): Tubes leading from the spiracles to the tracheoles that are part of the gaseous exchange system.
• Tracheoles: Very small tubes that make up the respiratory system of insects and carry gases from the tracheae to the cells.
• Vein: A type of blood vessel that carries blood into the heart from other parts of the body.
• Ventricle: A type of chamber in the heart which receives blood from the atrium above it and pumps it out of the heart.
• Venule: A smaller type of blood vessel that connects capillaries with veins.
• Arteriole: A smaller type of blood vessel that connects arteries with capillaries.
• Xerophyte: A type of plant that is adapted to survive in places with very little water.
• Xylem: The tissue that transports water in the stem and leaves of plants.
• Vena cava: The main vein that carries deoxygenated blood into the right atrium of the heart.