The formation of tissue fluid relies on the balance of hydrostatic and oncotic pressures. A student studied a capillary bed and recorded the pressures at both ends of the capillary, as shown in the table below:
| Location | Hydrostatic pressure (kPa\text{kPa}kPa) in Blood | Hydrostatic pressure (kPa\text{kPa}kPa) in Tissue Fluid | Oncotic pressure (kPa\text{kPa}kPa) in Blood | Oncotic pressure (kPa\text{kPa}kPa) in Tissue Fluid |
|---|---|---|---|---|
| Arteriole end | 4.8 | 1.2 | -3.5 | -1.1 |
| Venule end | 2.0 | 1.2 | -3.5 | -1.1 |
Given that the net pressure at the arteriole end is +1.2 kPa+1.2\text{ kPa}+1.2 kPa, calculate the net pressure at the venule end. Be sure to include the correct sign (+++ or −-−) with your answer.
Using the data in the table, explain why tissue fluid forms at the arteriole end but is reabsorbed back into the blood at the venule end.
15 exam-style questions on OCR A A Level Biology Transport in animals. Each one has a worked solution and a mark scheme showing where the marks go.