3. Exchange & Transport: Key Terms

• Alveoli: Tiny air sacs in the lungs located at the ends of bronchioles, providing a large surface area for gas exchange.

• Amylases: Enzymes that break down polysaccharides into simpler sugars.

• Antiporter: A membrane protein that transports molecules in opposite directions across a membrane.

• Aorta: The main artery that carries oxygenated blood from the heart at high pressure.

• Arteriole: A small blood vessel that connects arteries to capillaries.
• Artery: A blood vessel that transports blood away from the heart.
• Atrium: A heart chamber that receives blood from a vein and transfers it to a ventricle.
• Bile salts: Molecules in the small intestine that aid lipid emulsification, increasing the surface area for breakdown.
• Bronchi: Two airways branching from the trachea and leading to smaller bronchioles.

• Bronchioles: Small branches of the bronchi ending at the alveoli.
• Capillary: A tiny blood vessel with thin walls, facilitating substance exchange in tissues.
• Capillary bed: A network of capillaries supplying blood to tissues.
• Coronary artery: The main artery supplying blood to the heart muscle.
• Co-transport: Membrane transport involving the simultaneous movement of two molecules across the membrane.
• Diaphragm: A large muscle beneath the lungs that changes lung volume to facilitate breathing.
• Endopeptidase: Enzymes that break peptide bonds within polypeptides.
• Exopeptidases: Enzymes that hydrolyse peptide bonds at the ends of proteins.
• External intercostal muscles: Muscles located outside the ribs that aid in inhalation.

• Gill filaments: Structures in fish gills that extend from the gill arch, aiding in gas exchange.
• Gill lamellae: Small structures on gill filaments that increase the surface area for gas exchange.
• Haemoglobin: A protein in red blood cells with a quaternary structure, specialised for oxygen transport.
• Internal intercostal muscles: Muscles inside the ribs that facilitate forced exhalation.
• Left atrium: The heart chamber that receives oxygenated blood from the pulmonary vein and transfers it to the left ventricle.
• Left ventricle: The heart chamber that pumps oxygenated blood from the left atrium to the body.
• Lipase: Enzymes that break down lipids into glycerol and fatty acids.
• Membrane-bound dipeptidases: Enzymes embedded in membranes that break dipeptides into individual amino acids.
• Membrane-bound disaccharidases: Enzymes in membranes that hydrolyse disaccharides into monosaccharides.
• Micelles: Aggregates of lipid molecules that aid in lipid absorption by forming hydrophobic capsules.
• Phloem: Plant tissue responsible for transporting organic substances from their source to where they are needed.
• Positive cooperativity: A process where oxygen binding to haemoglobin increases its affinity for more oxygen.
• Pulmonary artery: The artery that carries deoxygenated blood from the heart to the lungs for oxygenation.
• Pulmonary vein: The vein that carries oxygenated blood from the lungs back to the heart.
• Renal artery: The artery that delivers oxygenated blood from the heart to the kidneys.
• Renal vein: The vein that returns deoxygenated blood from the kidneys to the heart.
• Right atrium: The heart chamber that receives deoxygenated blood from the vena cava and passes it to the right ventricle.
• Right ventricle: The heart chamber that pumps deoxygenated blood from the right atrium to the lungs.
• Spiracles: Openings on insect surfaces that enable gas exchange with the environment.
• Spongy mesophyll: Loosely packed plant tissue with air spaces, optimised for gas exchange.
• Stomata: Small pores on leaves controlled by guard cells to regulate water loss and gas exchange.
• Symporter: A membrane protein that transports molecules in the same direction across a membrane.
• The Bohr effect: A reduction in haemoglobin's oxygen affinity in regions with high carbon dioxide levels.
• Tissue fluid: Fluid that bathes cells, providing nutrients and gases for exchange.
• Trachea: The main airway for transporting air between the larynx and bronchi in mammals.
• Trachea (insects): Tubes leading from spiracles to tracheoles, forming part of the insect respiratory system.
• Tracheoles: Tiny tubes in insects that transport gases from tracheae to individual cells.
• Vein: A blood vessel that carries blood toward the heart.
• Vena cava: The vein that delivers deoxygenated blood to the right atrium of the heart.
• Ventricle: A heart chamber that pumps blood from the atrium out of the heart.
• Venule: A small blood vessel connecting capillaries to veins.
• Xerophyte: Plants adapted to survive in arid environments.
• Xylem: Plant tissue that transports water and dissolved minerals from roots to leaves.