Name the structures A, B and C.
When the water potential of the blood falls, the posterior pituitary gland secretes ADH. Suggest reasons why the water potential of the blood may decrease.
Diabetes insipidus is a condition that affects kidney osmoregulation. One form of diabetes insipidus is due to a tumour in the pituitary gland, causing decreased secretion of ADH. Suggest the symptoms that would occur in a person with diabetes insipidus.
Neurogenic diabetes insipidus (NDI) is another form of diabetes insipidus. In NDI, ADH molecules cannot bind to the receptor proteins found in the cell-surface membranes of the collecting duct cells. With reference to Fig. 1.1, explain the effect on the cell surface membrane labelled P if ADH cannot bind to the receptor proteins.
NDI is caused by a recessive allele of the gene that codes for the receptor protein. The gene is on the X chromosome. Explain why a man with NDI could not have inherited the condition from his father.