A low oxygen concentration also causes the amount of mRNA in the specialised kidney cells to increase. Suggest and explain why this rise in the amount of mRNA occurs.
EPO is kept in secretory vesicles before it leaves the specialised kidney cells. Outline how EPO is released from the cells.
All body cells are bathed in circulating blood plasma containing EPO, yet only certain target cells respond. Suggest and explain how EPO acts on target cells and why other cells are not affected.
EPO cannot cross the cell surface membrane to enter the bone marrow cells. Suggest one reason why this occurs.
Red blood cells develop from undifferentiated cells in the bone marrow that can keep dividing by mitosis. State the name of this type of undifferentiated cell.
In an investigation of the body’s response to EPO, a group of healthy young men received EPO injections each day for four weeks. The haemoglobin (Hb) concentration for each subject was measured at the start of the investigation and then at one-week intervals for the next ten weeks. The first measurement was made two weeks before the first EPO injection was given. Fig. 3.1 shows the mean results for the subjects. Describe the results shown in Fig. 3.1 and suggest explanations for these results.
The concentration of EPO in the blood plasma of a person will rise when travelling from sea level to a high altitude. This is a response to the decrease in oxygen partial pressure in the atmosphere. Explain why an increase in EPO blood plasma concentration will be of benefit if the person remains at high altitude.