Section 2 h) Key Words

Antibodies: Produced by lymphocytes, they latch onto pathogens and mark them as a target for other white blood cells to engulf or destroy.

Antigens: Chemical markers on pathogens that make them identifiable.

Aorta: The largest artery, that carries oxygenated blood away from the heart. Connected to the left ventricle.

Artery: A vessel carrying blood away from the heart. Thick walls, small lumen and high pressure.

Atrium: The two smaller chambers of the heart are the atria. They take in blood from the vena cava and the pulmonary vein.

Blood: The fluid found in the circulatory system that carries nutrients and waste to and from cells. Most importantly, it carries oxygen and glucose.

Capillary: The smallest type of blood vessel. Walls are one cell thick, and the lumen are very tiny.

Circulatory system: The system in the body that transports blood (containing nutrients etc.) around the body.

Haemoglobin: A red, iron-containing protein found in red blood cells. Bonds with oxygen to allow it to be carried around the body.

Hepatic: To do with the liver.

Lumen: The hollow inside blood vessels.

Lymphocytes: White blood cells that detect antigens and produce antibodies. Responsible for immune responses.

Mesenteric: To do with the gut.

Oxyhaemoglobin: The compound formed when oxygen bonds with haemoglobin.

Pathogens: Microorganisms or viruses that cause illness or disease.

Phagocytes: White blood cells that engulf foreign materials in the blood.

Phloem: The vessel in a plant that transports mineral glucose and amino acids to all of the cells.

Plasma: Makes up 55% of the blood, and is mostly water. Contains salts and mineral ions, and is pale yellow.

Platelets: Small fragments of cells that aid with clotting.

Pulmonary: To do with the lungs.

Red blood cells: Biconcave, red cells with no nucleus. Make up 45% of the blood, and contain haemoglobin to carry oxygen.

Renal: To do with the kidneys.

Sieve plate: The plate of cellulose containing holes in the phloem vessels.

Translocation: The process by which glucose and amino acids are moved through the phloem.

Transpiration: The process of evaporation and diffusion of water from the leaf. Cohesion between molecules mean more water is pulled up, creating a transpiration stream.

Vein: Vessels in the circulatory system that carry blood towards the heart. Large lumen and thin walls.

Vena cava: The largest vein. It carries deoxygenated blood back into the heart, connected to the right atrium.

Ventricle: The two larger chambers of the heart. Pump blood out of the heart, connected to the pulmonary artery and the aorta.

White blood cells: Lymphocytes and phagocytes are both white blood cells. They are responsible for the immune response.

Xylem: The tube in plants that is responsible for transporting water and mineral ions throughout the plant.