Red blood cells and plasma proteins, such as albumin, stay inside the capillaries and are not present in tissue fluid. Explain why red blood cells and albumin do not leave the capillary.
Name the chemical reagent or reagents used to test a blood plasma sample for protein, and state the colour change that appears if protein is present.
If a person leaves sea level and spends a few months at high altitude, the number of red blood cells per $\text{mm}^3$ of blood increases. Explain why this increase occurs.
A reduced blood albumin concentration may cause oedema. Oedema is a tissue swelling caused by tissue fluid collecting around body cells in the capillary network. Suggest and explain how a low blood albumin concentration can lead to oedema.
Albumin carries some cell signalling molecules from the cells in which they are made to their target cells. These signalling molecules bind to specific cell surface membrane proteins on the target cells. Name the type of membrane protein that the cell signalling molecules bind to.