Functioning organisms - 03 Circulatory system


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A closer look at the circulatory system of humans for Year 8 Science students.

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Functioning organisms - 03 Circulatory system

  1. 1. FUNCTIONING ORGANISMS. 03. Circulatory system. Ian Anderson Saint Ignatius College Geelong
  2. 2. CIRCULATORY SYSTEM.  Responsible for  Transporting oxygen and nutrients to our cells.  Collecting wastes from our cells.  Consists of  Heart.  Blood vessels.  Blood. Source:
  3. 3. CIRCULATORY SYSTEM.  Double circuit.  Oxygenated and deoxygenated blood is kept separate from each other.  One circuit pumps oxygenated blood to body.  Other circuit pumps deoxygenated blood to lungs. Source: Russell et al. (2011)
  4. 4. THE HEART.  Muscular pump (actually two pumps in one!).  The left side of the heart receives oxygenated blood from the lungs and then pumps it around the body.  The right side of the heart receives deoxygenated blood from the body and then pumps it to the lungs.  Made up of four chambers.  Left and right atria.  Collect blood from either the body or lungs.  Left and right ventricles.  Pump blood to either the body or lungs.  Valves between atrium & ventricle prevent backflow of blood.
  5. 5. THE HEART. Systemic circuit (LHS).  Pumps oxygenated blood to body. Lungs Left atrium Left ventricleBody Source: Sharwood (2005)
  6. 6. THE HEART. Source: Sharwood (2005) Systemic circuit (LHS).  Oxygenated blood to body.  Wall of left ventricle thicker than right ventricle.  Pumps blood to whole body under high pressure.
  7. 7. THE HEART. Source: Sharwood (2005) Pulmonary circuit (RHS).  Deoxygenated blood to lungs. Body Right atrium Right ventricleLungs
  8. 8. THE HEART. Source: Sharwood (2005) Pulmonary circuit.  Deoxygenated blood to lungs.  Wall of left ventricle thinner than left ventricle.  Pumps blood to lungs under lower pressure.
  9. 9. BLOOD VESSELS. Blood is transported around the body in three different kinds of blood vessels:  Arteries.  Veins.  Capillaries.
  10. 10. BLOOD VESSELS. Arteries.  Carry blood away from the heart to the body.  Carry oxygenated blood except for the pulmonary artery.  Have thick, muscular walls with elastic fibres.  In order to withstand the increased pressure of the blood as it is pumped from the heart. Source:
  11. 11. BLOOD VESSELS. Veins.  Carry blood towards the heart from the body.  Have valves in order to prevent backflow of blood.  Have relatively thin walls.  Blood is under lower pressure than in arteries. Source: Source:
  12. 12. BLOOD VESSELS. Capillaries. As arteries move away from the heart they divide, eventually forming arterioles, before finally forming capillaries.  Carry blood to and from body cells.  Most cells are very close to a capillary.  Blood under very low pressure.  Very narrow.  Thin, permeable walls.  Site of exchange of O2, CO2, nutrients & wastes. Source:
  13. 13. BLOOD. Made up of  Plasma.  Red blood cells (erythrocytes).  White blood cells (leukocytes).  Platelets. Total blood volume is ~4-5L. Source: Russell et al. (2011)
  14. 14. BLOOD. Plasma.  The liquid component (clear, straw coloured).  Makes up ~55-58% of blood.  Contains ions, dissolved gases, proteins, hormones and wastes.  Main role is to transport all the components of blood.
  15. 15. BLOOD. Red blood cells (erythrocytes).  Makes up ~45% of blood.  Transport O2 and CO2.  Lack a nucleus.  Contain haemoglobin (iron containing protein that carries oxygen). Source:
  16. 16. BLOOD. White blood cells (leucocytes).  Makes up <1% of blood.  Have a nucleus.  Play an active role in the defence against infection and in the immune system.  Able to move out of bloodstream into surrounding tissues. Source:
  17. 17. BLOOD. Platelets.  Specialised fragments of larger cells.  Play an important role in the clotting of blood. Source:
  18. 18. BIBLIOGRAPHY. Russell, P.J., Hertz, P.E., & McMillan, B. (2011). Biology: The Dynamic Science. Canada: Thomson Brooks/Cole. Sharwood, J. (Ed.). (2005). Science Edge 2. Melbourne: Thomson Learning.
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