Biology › Animal transport and cardiovascular biology

Animal transport and cardiovascular biology

Unit B09 · 3 lessons.

Pressure links the three lessons. Pressure differences between the chambers of the heart open and close every valve, so the cardiac cycle is read from a pressure-time graph. Blood pressure falls with distance from the heart, and that fall explains the structure of each vessel wall and how tissue fluid forms at the arteriole end of a capillary. For haemoglobin the pressure is the partial pressure of oxygen, which is the axis of the dissociation curve.

Read surface area to volume ratio first, which explains why a large animal needs a circulation. Diffusion and osmosis gives the water potential behind tissue fluid. AQA (3.3.4.1), OCR A (3.1.2), Cambridge International (topic 8) and Pearson Edexcel Biology B (Topic 4) examine the unit as AS content, and Pearson Edexcel Biology A places the heart and vessels in Topic 1. The control of heart rate is A-level content for AQA, OCR A and both Pearson specifications.

Notes

Illustrated notes for each topic in this unit, with worked examples and a checklist of objectives.

• The heart and cardiac cycle
  Why large active animals need a mass transport system, how double circulation differs from single, the structure of the mammalian heart including the…
• Blood vessels, tissue fluid and lymph
  The structure of arteries, arterioles, capillaries, venules and veins related to function and to the pressure each carries; why capillary walls are…
• Haemoglobin and oxygen dissociation curves
  Haemoglobin as a conjugated globular protein, cooperative binding and the sigmoid dissociation curve, reading loading and unloading from the curve…

Practical work

The practical capabilities this unit's work belongs to, each with its techniques, its calculations and the errors that cost marks.

• Dissection and biological drawing