The document summarizes key concepts about the circulatory system and gas exchange. It describes the heart's chambers and valves that direct blood flow, as well as the vessels that supply the heart. The lungs and alveoli are identified as the sites of gas exchange, where oxygen passes into the blood and carbon dioxide passes out. Red blood cells are described as carrying oxygen in the blood using the protein hemoglobin.

3. Chambers of the Heart Right atrium Right ventricle Left atrium Left ventricle Internal wall Cardiac muscle

4. Valves of the Heart Atrioventricular valves Semi lunar valves Semi lunar valves Atrioventricular valves Direction of blood flow

5. Coronary Arteries Artery carrying O 2 rich blood to cardiac cells Damaged artery clogging with fatty deposits

7. Vena cava: Carries deoxygenated blood from body to heart. Pulmonary Artery: Carries deoxygenated blood from heart to lungs. Pulmonary Vein: Carries oxygenated blood from lungs to heart. Aorta: Carries oxygenated blood from heart to all body parts.

8. Blood Vessels Artery: carries blood away from the heart. Vein – carries blood to the heart Thick muscular wall Thinner walls than arteries. Contain valves to prevent back flow.

9. The capillary wall is one cell thick O 2 and food CO 2 and waste Capillaries

12. Lungs Trachea Lung Ribs Diaphragm Pleural cavity Intercostal muscles Alveoli

13. Bronchioles Rings of cartilage Bronchus

15. Structures and Functions of the Alveoli To allow the carbon dioxide to be brought to the alveoli and for the oxygen to be taken away Network of blood capillaries surrounded by alveoli Allows efficient diffusion of gases The wall of the alveoli and capillary is one cell thick Allows gases to dissolve in water for diffusion Alveolar surface is moist Large surface area far gas exchange Bronchioles split to form an abundance of alveoli Function Feature

21. Haemoglobin Protein chains (blue) Haem groups (pink) -Each haem group contains an atom of iron which allows an oxygen molecule to attach. -One haem group binds with one oxygen molecule, so each molecule of haemoglobon can carry four oxygen molecules.

22. When there is a high O 2 concentration (e.g in lungs) haemoglobin associates with O 2. When there is a low O 2 concentration (e.g in tissue) haemoglobin dissociates with O 2. oxyhaemoglobin haemoglobin + oxygen haemoglobin + oxygen oxyhaemoglobin

24. A pathogen is an organism that can cause disease in the body. The body’s first line defences prevent the entry of these harmful organisms. First line defences can act as a barrier: skin, mucus First line defences can act to discourage pathogens: saliva, tears, acid, harmless bacteria First Line Defences

25. Second Line Defences These deal with pathogens that have made it past the first line defence. A macrophage is a special type of large white blood cell which can engulf and digest bacteria. Macrophages engulf and digest bacteria, dead cells, small particles and unwanted matter. This is a very general response and not specific against any one pathogen.

26. Phagocytosis Phagocytosis is the process by which white blood cells engulf and breakdown bacteria etc. http:// highered . mcgraw -hill.com/sites/0072495855/student_view0/chapter2/animation__phagocytosis.html

28. General Immunity: -Non- specific. -Protects against a wide variety of microorganisms. - Phagocytosis by macrophages is an example. Specific Immunity: - Antibodies are produced by white blood cells. -The antibodies recognise and destroy specific microorganisms.

29. Producing Antibodies The surface of all cells and viruses have substances known as antigens . These antigens are specific to the cell and act as an identity tag. A persons own cells have self-antigens which are not recognised as harmful. Bacteria and viruses carry non-self antigens and are then recognised as potentially harmful.

30. There are millions of different lymphocytes (type of white blood cell). Each lymphocyte will recognise one specific non-self antigen. The lymphocyte will then produce an antibody which will specifically attack that antigen. Antibodies (Y-shape structure) produced by a specific lymphocyte attack the antigens. Bacteria or virus with non-self antigens

31. Passive Immunity: The antibody is passed on ready made into the body e.g. from a mother to a new born via breast milk. This form of immunity is temporary. Active Immunity: Antibodies are produced in the body as a response to disease antigens or vaccines. Vaccines use altered pathogens that stimulate the immune system without causing disease!