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  1. 1. Transport in Humans<br />The Blood Circulatory System<br />
  2. 2. Learning Outcomes<br /><ul><li>Explain the importance of the circulatory system in linking all systems of the organism together.
  3. 3. Describe the structure and function of the heart in moving blood around the body.
  4. 4. Describe the structure and function of the blood vessels.
  5. 5. Describe the structure and function of the blood in supporting life.</li></li></ul><li>Characteristics of a Circulatory System<br /><ul><li>Open circulatory system:
  6. 6. Blood pumped by the heart leaves the open-ended vessels for a series of blood spaces surrounding the tissues.
  7. 7. When the heart relaxes, the blood flows back into the vessels through pores.
  8. 8. Insects have an open circulatory system.</li></li></ul><li>Characteristics of a Circulatory System<br /><ul><li>Closed circulatory system:
  9. 9. The circulating fluid does not leave the blood vessels or come in direct contact with the blood tissues at any time.
  10. 10. Fish possesses a closed circulatory system.</li></li></ul><li>The Double Circulation<br /><ul><li>Presence of two distinct circuits of blood flow:</li></li></ul><li>The Double Circulation<br /><ul><li>One circuit pumps blood to the lungs where exchange of gases take place – pulmonary circuit.
  11. 11. The systemic circulation connects the heart and all the body tissues except the lungs. It is responsible for transporting:
  12. 12. Nutrients from the digestive system to the tissues that need the food.
  13. 13. Regulatory substances from various organs and glands to the sites where the hormone will take effect.
  14. 14. Wastes from the tissues to the relevant excretory organs.</li></li></ul><li>9.1 The Circulatory Fluid: Blood<br /><ul><li>Our blood transports:
  15. 15. Nutrients from the digestive system,
  16. 16. Oxygen from the lungs,
  17. 17. Carbon dioxide and other wastes from tissue cells,
  18. 18. Hormones from various organs such as the pancreas, as well as cells which provide protection for the body.</li></li></ul><li>9.1 The Circulatory Fluid: Blood<br /><ul><li>Our blood transports:</li></li></ul><li>9.2 The Pump: The Heart<br />
  19. 19. 9.2 The Pump: The Heart<br />
  20. 20. 9.2 The Pump: The Heart<br />Heart Tissue<br /><ul><li>The whole heart is a mass of branching interconnecting cardiac muscle fibres.
  21. 21. The membranes of the muscle tissue enable ions to diffuse rapidly across them.
  22. 22. The rapid spread of electrical impulses that results, enables the whole mass of heart muscle to behave as one unit when contracting or relaxing.</li></li></ul><li>9.2 The Pump: The Heart<br />Control of the Heartbeat<br /><ul><li>Four chambers of the heart must coordinate to function as a pump.
  23. 23. The group of specialised cells to pump is called the pacemaker.</li></li></ul><li>9.2 The Pump: The Heart<br />Control of the Heartbeat<br /><ul><li>Electrical signals generated by the pacemaker pass along the muscle fibres of both atria to another specialised set of muscle cells.
  24. 24. These signals stimulate the atria causing them to contract.</li></li></ul><li>9.2 The Pump: The Heart<br />Control of the Heartbeat<br /><ul><li>Transmission of the electrical impulse by the second set of specialised cells.
  25. 25. Blood in the atria transferred to the ventricles.</li></li></ul><li>9.2 The Pump: The Heart<br />Control of the Heartbeat<br /><ul><li>Signal spreads to the base of the two ventricles, causing simultaneous contraction of the ventricles.
  26. 26. Cardiac muscle relaxes after a series of contractions.</li></li></ul><li>9.2 The Pump: The Heart<br />Cardiovascular Disease<br />Angina:<br /><ul><li>Feeling of pressure, tightness, discomfort or heaviness in the chest beneath the beneath the breastbone.
  27. 27. May also be felt in left arm or shoulder, the neck or the lower jaw.</li></li></ul><li>9.2 The Pump: The Heart<br />Cardiovascular Disease<br />Heart attack (myocardial infarction):<br /><ul><li>Build-up of fatty deposits of cholesterol in the inner wall of the artery.
  28. 28. If fibrous tissue is deposited along with the cholesterol, the plaques calcify and harden – arteriosclerosis.</li></li></ul><li>9.2 The Pump: The Heart<br />Cardiovascular Disease<br /><ul><li>Factors which increase the risk of getting a heart attack:
  29. 29. Family history of heart disease;
  30. 30. Being a male;
  31. 31. Age;
  32. 32. Smoker;
  33. 33. High intake of saturated fats and salt;
  34. 34. Lack of exercise;
  35. 35. High blood pressure;
  36. 36. Intake of excessive sugars;
  37. 37. High intake of alcohol.</li></li></ul><li><ul><li>The human heart is made up of two pumps: one pumps blood to the lungs; the other pumps blood to the rest of the body.
  38. 38. The presence of valves between the atria and ventricles, and at the entrance of the pulmonary artery and aorta ensures that the flow of blood in the heart is in one direction.
  39. 39. Both atria contract at the same time, pushing blood into the ventricles.
  40. 40. Both ventricles contract at the same time, pushing blood out of the heart.</li></li></ul><li><ul><li>The coordinated rhythmic pumping of the heart is possible because of the pacemaker and the electrical signals it transmits to the heart tissue.
  41. 41. The beating of the heart forcing the blood out into the arteries gives rise to the pulse.
  42. 42. The heart tissue gets its blood from coronary arteries. These branch from the aorta just as it leaves the heart. Blockage of any part of these arteries could cause the heart tissue they supply, to die.</li></li></ul><li><ul><li>The risk of getting a heart attack can be reduced by leading a healthy lifestyle that involves proper diet and exercise.</li>