2.74 ADH

2.74 Describe the role of ADH in regulating the water content of blood,

- ADH = Anti-Diuretic Hormone. Is produced in a region of the brain called the Hypothalamus, and its target is the kidney.

- The affect of ADH is to control and alter the composition or quantity of water in blood.

- So ADH has the ability to make the blood more or less concentrated. And we previously established that it is very important for the tissue fluid to be isotonic with the cytoplasm of the cells. This is the role of ADH

- ADH targets the collecting duct. The affect of ADH is that it allows more water to go into the collecting duct increasing the amount of water in the blood. So we have already learned that the collecting duct is where water is selectively reabsorbed into the blood. So applying more of the hormone ADH would make the collecting duct walls more porous so more water can escape from the glomerule filtrate into the collecting duct.

- The consequences of ADH secretion is that the urine coming from the bladder would be more concentrated and have a lower volume. So with ADH secretion more water goes back into the blood, the urine becomes more concentrated, and the volume decreases.

- Our brain releases different amount of the hormone ADH depending on things like the weather - hot or cold day? so that our blood has enough water in it to keep us hydrated.