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Biology_A-level_Cie

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  1. 1-1-the-microscope-in-cell-studies
    5 主题
  2. 1-2-cells-as-the-basic-units-of-living-organisms
    5 主题
  3. 2-1-testing-for-biological-molecules
    3 主题
  4. 2-2-carbohydrates-and-lipids
    8 主题
  5. 2-3-proteins
    6 主题
  6. 2-4-water
    2 主题
  7. 3-1-mode-of-action-of-enzymes
    5 主题
  8. 3-2-factors-that-affect-enzyme-action
    8 主题
  9. 4-1-fluid-mosaic-membranes
    4 主题
  10. 4-2-movement-into-and-out-of-cells
    12 主题
  11. 5-1-replication-and-division-of-nuclei-and-cells
    6 主题
  12. 5-2-chromosome-behaviour-in-mitosis
    2 主题
  13. 6-1-structure-of-nucleic-acids-and-replication-of-dna
    4 主题
  14. 6-2-protein-synthesis
    5 主题
  15. 7-1-structure-of-transport-tissues
    4 主题
  16. 7-2-transport-mechanisms
    7 主题
  17. 8-1-the-circulatory-system
    7 主题
  18. 8-2-transport-of-oxygen-and-carbon-dioxide
    5 主题
  19. 8-3-the-heart
    4 主题
  20. 9-1-the-gas-exchange-system
    6 主题
  21. 10-1-infectious-diseases
    3 主题
  22. 10-2-antibiotics
    3 主题
  23. 11-1-the-immune-system
    4 主题
  24. 11-2-antibodies-and-vaccination
    6 主题
  25. 12-1-energy
    5 主题
  26. 12-2-respiration
    11 主题
  27. 13-1-photosynthesis-as-an-energy-transfer-process
    8 主题
  28. 13-2-investigation-of-limiting-factors
    2 主题
  29. 14-1-homeostasis-in-mammals
    8 主题
  30. 14-2-homeostasis-in-plants
    3 主题
  31. 15-1-control-and-coordination-in-mammals
    12 主题
  32. 15-2-control-and-coordination-in-plants
    3 主题
  33. 16-1-passage-of-information-from-parents-to-offspring
    5 主题
  34. 16-2-the-roles-of-genes-in-determining-the-phenotype
    7 主题
  35. 16-3-gene-control
    3 主题
  36. 17-1-variation
    4 主题
  37. 17-2-natural-and-artificial-selection
    7 主题
  38. 17-3-evolution
    2 主题
  39. 18-1-classification
    5 主题
  40. 18-2-biodiversity
    7 主题
  41. 18-3-conservation
    6 主题
  42. 19-1-principles-of-genetic-technology
    11 主题
  43. 19-2-genetic-technology-applied-to-medicine
    4 主题
  44. 19-3-genetically-modified-organisms-in-agriculture
    2 主题
  45. 1-1-the-microscope-in-cell-studies
  46. 1-2-cells-as-the-basic-units-of-living-organisms
  47. 2-1-testing-for-biological-molecules
  48. 2-2-carbohydrates-and-lipids
  49. 2-3-proteins
  50. 2-4-water
  51. 3-1-mode-of-action-of-enzymes
  52. 3-2-factors-that-affect-enzyme-action
  53. 4-1-fluid-mosaic-membranes
  54. 4-2-movement-into-and-out-of-cells
  55. 5-1-replication-and-division-of-nuclei-and-cells
  56. 5-2-chromosome-behaviour-in-mitosis
  57. 6-1-structure-of-nucleic-acids-and-replication-of-dna
  58. 6-2-protein-synthesis
  59. 7-1-structure-of-transport-tissues
  60. 7-2-transport-mechanisms
  61. 8-1-the-circulatory-system
  62. 8-2-transport-of-oxygen-and-carbon-dioxide
  63. 8-3-the-heart
  64. 9-1-the-gas-exchange-system
  65. 10-1-infectious-diseases
  66. 10-2-antibiotics
  67. 11-1-the-immune-system
  68. 11-2-antibodies-and-vaccination
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Mammalian heart structure

Heart structure

  • The human heart has a mass of around 300g and is roughly the size of a closed fist

  • The heart is a hollow, muscular organ located in the chest cavity

Diagram of a human heart showing blood flow. Red arrows indicate oxygenated blood; blue arrows indicate deoxygenated blood. Labels identify heart parts.
The human heart has four chambers and is separated into two halves by the septum

  • The heart is divided into four chambers

    • The two top chambers are atria and the bottom two chambers are ventricles

  • The left and right sides of the heart are separated by a wall of muscular tissue, called the septum

    • The septum is very important for ensuring blood doesn’t mix between the left and right sides of the heart

Valves in the heart

  • Valves in the heart:

    • Open when the pressure of blood behind them is greater than the pressure in front of them

    • Close when the pressure of blood in front of them is greater than the pressure behind them

  • Valves are important for keeping blood flowing forward in the right direction and stopping it flowing backwards

    • They are also important for maintaining the correct pressure in the chambers of the heart

  • The right atrium and right ventricle are separated by the atrioventricular valve

    • This is also known as the tricuspid valve

  • The right ventricle and the pulmonary artery are separated by the pulmonary valve

  • The left atrium and left ventricle are separated by the mitral valve

    • This is also known as the bicuspid valve

  • The left ventricle and aorta are separated by the aortic valve

  • There are two blood vessels bringing blood to the heart:

    • Vena cava

    • Pulmonary vein

  • There are two blood vessels taking blood away from the heart:

    • Pulmonary artery

    • Aorta

Coronary arteries

  • The heart is a muscle and so requires its own blood supply for aerobic respiration

  • The heart receives blood through arteries on its surface, called coronary arteries

  • It’s important that these arteries remain clear of plaques, as this could lead to angina or a heart attack (myocardial infarction)

Diagram of the heart showing right and left coronary arteries, with text explaining coronary arteries supply nutrients and remove waste products.
The coronary arteries cover the outside of the heart, supplying it with oxygenated blood

Examiner Tips and Tricks

When looking at the heart, remember the right side of the heart will appear on the page as being on the left. This is because the heart is labelled as if it were in your body and flipped around.