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Higher Human Biology

This unit explores the critical role of transport systems in larger organisms, focusing on the necessity for efficient nutrient delivery and gas exchange. While diffusion suffices for small cells, larger organisms require specialized systems to transport essential substances quickly. Key concepts include understanding surface area-to-volume ratios, the mechanisms of arterial and venous blood flow, and the significance of capillaries in nutrient exchange. Additionally, it addresses common heart problems and preventative measures like managing cholesterol, weight, and lifestyle choices.

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Higher Human Biology

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  1. Higher Human Biology Unit 2 The Need for Transport

  2. Which has the largest surface area to volume ratio?

  3. side of cube side*side Area of Side side*side*6 Area of Cube's Surface side*side*side Volume Ratio of Surface Area to Volume 2 2*2 4 2*2*6 24 2*2*2 8 3 to 1 4 4*4 16 4*4*6 96 4*4*4 64 3 to 2 6 6*6 36 6*6*6 216 6*6*6 216 3 to 3 8 8*8 64 8*8*6 384 8*8*8 512 3 to 4 12 12*12 144 12*12*6 864 12*12*12 1728 3 to 6 20 20*20 400 20*20*6 2400 20*20*20 8000 3 to 10

  4. Why the need for a transport system? • Diffusion is to slow for larger organisms where absorbing organs are located at a distance from the cells in need of food and oxygen • Hence larger organisms need a specialised transport system to deliver essential nutrients to living cells at a sufficiently rapid rate

  5. Artery

  6. Vein

  7. Capillaries

  8. Tissue Fluid • Blood is forced into narrow capillaries and undergoes a form of pressure filtration and much of the plasma is squeezed out through the thin walls. This liquid is called tissue fluid (same as blood plasma except it contains little or no protein)

  9. The need to circulate blood To allow exchanges of materials between bloodstream and • external environment (e.g. absorption of oxygen and release of carbon dioxide at alveoli) • Internal environment (e.g. release of oxygen and removal of carbon dioxide at living cells)

  10. Double circulatory system

  11. The coronary artery • The first two branches of the aorta

  12. Heart Problems • Coronary heart disease • Atherosclereosis • Angina • How to avoid them – • Reduce cigarette smoking, stress, fat and cholesterol intake, ideal weight and regular exercise

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