Circulatory system

• Pulse: the expansion and contraction of the arteries due to the pumping action of the heart
• Blood pressure: the force of blood as it passes through an artery
• Lymph: a pale yellow-coloured fluid containing water, white blood cells, proteins and lipids
• Lymph vessels: blind-ending tubes that carry lymph. Many lymph vessels have valves
• Lymph nodes: small swellings along the length of many lymph vessels. They filter bacteria and produce and store white blood cells
• Active immunity: antibodies are made by the organism itself
• passive immunity: antibodies are received that have been made in another organism
• Antigen: a chemical that stimulates the production of antibodies