Chapter 8 Transport in Humans Lesson 3 - Structure and function of the human heart

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Chapter 8 Transport in Humans Lesson 3 - Structure and function of the human heart

  1. 1. 3) Heart
  2. 2. Lesson Objectives: • Double & single circulation • Structure of heart • Mode of action of heart
  3. 3. Lung All other parts of the body The mammalianThe mammalian circulation plancirculation plan Double circulation in mammals Heart Blood Blood vessels Circulatory system pulmonary circulation systemic circulation As blood passes through heart twice, this also known as double circulation
  4. 4. The human circulatory systemThe human circulatory system The pulmonary circulationThe pulmonary circulation 2 The blood is pumped through pulmonary artery into lungs for gas exchange 3 The blood becomes oxygenated 4 The blood flows through pulmonary veins to left atrium 1 Deoxygenated blood in right ventricle
  5. 5. The human circulatory systemThe human circulatory system The systemic circulationThe systemic circulation 1 Oxygenated blood in left ventricle 2 The blood is pumped through aorta to all parts of the body except lungs 3 O2 and nutrients diffuse into cells while CO2 and wastes diffuse out 4 The blood flows through inferior/ superior vena cava to right atrium
  6. 6. Single circulation Systemic circulation
  7. 7. Heart Click me!
  8. 8. External Structure of heartExternal Structure of heart Heart consists of 4 chambers 2 atria (right atrium and left atrium) – smaller – on the upper part 2 ventricles – larger – below atria (plural) left atrium right atrium right ventricle left ventricle
  9. 9. Internal Structure of heartInternal Structure of heart Heart consists of 4 chambers 2 atriums – smaller – on the upper part 2 ventricles – larger – below atriums left atrium right atrium right ventricle left ventricle
  10. 10. Atriums and ventricles are separated by valves to prevent backflow of blood bicuspid valve Septum prevents mixing of blood in both sides of the heart chordae tendineae holds valves in position and avoids them to turn inside-out tricuspid valve semi-lunar valves
  11. 11. Blood flow and blood vessels aorta pulmonary artery superior vena cava inferior vena cava pulmonary veins from body from body to lung from lung deoxygenated blood oxygenated blood to body
  12. 12. Circulation of blood around the body Arterial supply Venous return
  13. 13. External Structure of heartExternal Structure of heart aorta pulmonary artery superior vena cava inferior vena cava pulmonary vein coronary artery coronary vein
  14. 14. Structure of heart bicuspid valve tricuspid valve Inferior vena cava Superior vena cava Pulmonary artery Pulmonary vein Right atrium Right ventricle Left atrium Left ventricle aortic valve Median septum aorta chordae tendineae Pulmonary valve
  15. 15. Activity: Label the following diagram of the heart in the worksheet provided
  16. 16. Names of important arteries & veins
  17. 17. quiz…
  18. 18. Label the external parts of the heart: 1. superior vena cava 2. aorta 3. pulmonary arteries 4. left atrium 5. right atrium 6. right ventricle 7. left ventricle 8. right coronary vein 9. right coronary artery 10. apex
  19. 19. Label the internal parts of the heart: 1. superior vena cava 2. right atrium 3. tricuspid valve 4. right ventricle 5. papillary muscle 6. aorta 7. pulmonary artery 8. left atrium 9. bicuspid valve 10. median septum
  20. 20. Mode of action of heart
  21. 21. Mode of action right atrium left atrium right ventricle contract simultaneously left ventricle pulmonary arch contract simultaneously aortic arch Backflow prevented by tricuspid valve Backflow prevented by bicuspid valve (atria contracts) (atria relaxes)
  22. 22. Mode of action • closing of tricuspid & bicuspid ‘ valves produce loud ‘lub’ sound (ventricular contraction/systole) • closure of semilunar valves produce ’dub’ sound (ventricular relaxation/diastole) • one systole + one diastole = one heartbeat • atria and ventricle work alternately
  23. 23. Blood pressure
  24. 24. Blood pressure • Force of blood exerted on blood vessel walls • Highest during ventricular systole, when blood is forced into arteries • Decreases during ventricular diastole • Varies in different parts of the body (arteries near heart → high; veins (far from heart → low) • Varies with individuals Normal person: systolic pressure = 120-140mm of mercury diastolic pressure = 75-90mm of mercury • Blood pressure is given as the systolic pressure being the first number than diastolic pressure being the second number e.g. 120/80 (120 over 80) • High blood pressure when blood pressure is 140/90 or higher
  25. 25. High blood pressure • High blood pressure when blood pressure is 140/90 or higher • May occur temporarily after heavy exercise or when a person is angry • Persistent high blood pressure (in middle- aged or elderly people) is a dangerous medical condition • Can be easily controlled if they see a doctor in time and follow the medical advice given
  26. 26. ***Pressure changes in the heart (Refer to pg 161 Biology Textbook) Recall • one systole + one diastole = one heartbeat • atria and ventricle work alternately (ventricular systole + atrial diastole occur simultaneously and atrial systole + ventricular diastole occur simultaneously)
  27. 27. Increase in pressure due to blood flowing into the ventricle when the atrium contracts Increase in pressure due to blood flowing into the aorta when the ventricle contracts Pressure in the aorta follows that of the pressure in the ventricle (pressure is slightly lower) Pressure in the aorta rises due to backflow of blood in the aorta
  28. 28. ‘O’ Level Bio P1 Nov 2008 ( D ) For bicuspid valve to open, pressure in the left atrium must be high and vice versa
  29. 29. ‘O’ Level Bio P1 Nov 2006 ( B ) Atrio-ventricular valve = bicuspid or tricupid valves Semi-lunar valve = valve in aorta Between W and X, ventricular pressure is increasing hence atrio ventricular valves would be closed and semi lunar valve would open as blood is pushed through the aorta
  30. 30. ‘O’ Level Bio P1 Nov 2006 ( C ) 0.6 s = one heartbeat 60/0.6 = 100 heartbeats per min
  31. 31. Pulse
  32. 32. Pulse (produced after every ventricular contraction) ventricular contraction aortic arch blood is pumped into arteries blood is pumped into arteries dilate increased pressure causes walls of arteries recoil Blood forced along in series of waves [Imagine a fireman’s hose]
  33. 33. Experiment to demonstrate the presence of valves in veins
  34. 34. Demonstrating the presence of valves Procedure: • Bandage the upper arm (valves in veins appear as small swellings) [see above] • Place 2 fingers at point Y • Using one finger push blood to point X • Blood flowed back to from X to b and no further
  35. 35. Heart diseases
  36. 36. Coronary Heart Disease
  37. 37. Coronary Heart Disease • Coronary arteries lie on the outside of the heart and carry blood to the muscles in the walls of the heart • Blood supply to the heart can be greatly reduced if the coronary arteries become blocked or narrowed Narrowing/ blocking of coronary arteries 1) Angina (chest pains) 2) Heart attack
  38. 38. Transverse sections of 2 arteries (cholesterol + polysaturated fats)
  39. 39. 1) Angina
  40. 40. 2) Heart Attack!!! • Fatty substances (cholesterol and polysaturated fats) may be deposited on the inner surfaces of the coronary arteries (atherosclerosis); • This narrows the lumen of these arteries + increases blood pressure; • Such an affected artery develops rough inner surfaces, which increases the risk of a blood clot being trapped in the artery (thrombosis); • If it occurs in the coronary arteries, the supply of blood and oxygen to the heart muscles may be completely cut off. The heart muscle cells may be damaged and die, triggering a heart attack.
  41. 41. Atherosclerosis
  42. 42. Atheroma formation A thrombus is an aggregate of a network of fibrin, platelets, and blood elements trapped by the fibrin net
  43. 43. Factors that increase the risk of atherosclerosis and coronary heart disease 1. A diet rich in cholesterol and saturated animal fats 2. Emotional stress 3. Smoking
  44. 44. Preventive measures against coronary heart disease • Proper diet – rich in dietary fibres; substitute animal fats with polyunsaturated plant fats • Proper stress management • Avoid smoking - Nicotine increases blood pressure - CO increases risk of fatty deposits on inner surfaces of arteries • Regular physical exercise - strengthens the heart and maintains elasticity of arterial walls
  45. 45. Ballooning & Stent Insertion

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