Summary
Antidiuretic hormone raises kidney water reabsorption when blood is too concentrated.
In depth
Osmoreceptors in the hypothalamus detect high plasma concentration; posterior pituitary releases ADH, making collecting ducts more permeable via aquaporins, so more water is reabsorbed. Alcohol inhibits ADH, causing dilute urine.
Thirst and ADH restore water balance. Dehydration raises plasma osmolarity. Overhydration dilutes it.
Key idea: ADH conserves water by concentrating urine.
ADH (vasopressin) is made in the hypothalamus and released from the posterior pituitary. It inserts aquaporin-2 channels into collecting duct cells, increasing water reabsorption and producing concentrated urine. Low ADH gives dilute urine. Alcohol and caffeine inhibit ADH release and have a diuretic effect. Thirst, controlled by the hypothalamus, drives drinking when osmolarity rises about 1 to 2 percent.
Diabetes insipidus results from lack of ADH (central) or kidney response (nephrogenic), causing large volumes of dilute urine, whereas SIADH causes excess water retention and low sodium. Dehydration raises plasma osmolarity, and overhydration can dilute sodium dangerously (hyponatraemia).
Example: after sweating heavily, ADH release increases, producing dark, small volumes of urine.
Frequently asked questions
What is Osmoregulation and ADH?
Antidiuretic hormone raises kidney water reabsorption when blood is too concentrated.
Which area of biology covers Osmoregulation and ADH, and how advanced is it?
Osmoregulation and ADH is one of the 51 topics in Human Physiology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Renin-Angiotensin-Aldosterone System, Nephron Function, Blood Glucose Regulation.
Can you give an example of Osmoregulation and ADH?
Diabetes insipidus is a lack of ADH action.
What should I learn before Osmoregulation and ADH?
Work through the Beginner topics in Human Physiology first, such as Homeostasis, Tissues and Organs, Skeletal System, then return to Osmoregulation and ADH. Intermediate topics assume the Beginner vocabulary.
What topics are related to Osmoregulation and ADH?
The closest topics to Osmoregulation and ADH are Renin-Angiotensin-Aldosterone System, Nephron Function, Blood Glucose Regulation, Countercurrent Multiplier. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Osmoregulation and ADH?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Osmoregulation and ADH. To practise the whole of Human Physiology, use the Human Physiology quiz.
How is Osmoregulation and ADH different from Renin-Angiotensin-Aldosterone System?
Osmoregulation and ADH: Antidiuretic hormone raises kidney water reabsorption when blood is too concentrated. Renin-Angiotensin-Aldosterone System: A hormone cascade that raises blood pressure by vasoconstriction and sodium retention. Read both side by side and note what each one explains.
How should I study Osmoregulation and ADH step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Renin-Angiotensin-Aldosterone System and explain the difference aloud. Finally, take the Human Physiology quiz and come back to this page for any question you miss.