Final answer:
The incorrect statement regarding ADH is that it causes the renal excretion of sodium, potassium, and water, whereas it actually reduces water excretion and promotes reabsorption in the kidneys to conserve water and regulate fluid balance.
Step-by-step explanation:
The statement that is not true of antidiuretic hormone (ADH) is: "3) Causes the renal excretion of sodium, potassium, and water." ADH, also known as vasopressin, is secreted by the posterior pituitary gland and is responsible for reducing water excretion in the kidneys. This is in response to signals from the hypothalamus when the blood volume is low or when the plasma is concentrated, for instance during dehydration. Instead of promoting excretion, ADH causes the kidneys to reabsorb water, thereby concentrating the urine and conserving water in the body. Deficiency in ADH secretion or action can lead to a condition known as diabetes insipidus, characterized by increased urine output and thirst due to the inability of the body to reabsorb water in the kidneys. ADH's role is crucial for maintaining fluid balance and pressure in the cardiovascular system.