Hormones are chemical signalling molecules that act as messengers in our body. They are secreted by endocrine glands such as pituitary, pineal, thymus, thyroid, adrenal glands, and pancreas. They travel along with the bloodstream and target every part of the body, affecting and regulating metabolism and many other processes including physiology, reproduction and behavior. A tiny amount of hormone is enough to bring a big change in our cells and tissues. Antidiuretic Hormone (ADH) and aldosterone are two hormones that target our kidney functions. Both hormones are responsible for maintaining water balance in our body. They act on the collecting duct of the kidneys and facilitate the re-absorption of water.
What is ADH?
Antidiuretic hormone or ADH is a peptide hormone made in the hypothalamus. It consists of nine amino acids. ADH travels to the posterior pituitary gland, and from there, it moves to the bloodstream. ADH is mainly responsible for maintaining the water balance in our body.
In response to an increase in blood osmolality or a decrease in blood volume, the pituitary gland releases ADH to the blood. It works on the collecting duct and increases the water permeability in order to control the amount of water reabsorbed by the kidney. Kidney reabsorbs and saves more water and makes urine more concentrated.
What is Aldosterone?
Aldosterone is a steroid hormone. In fact, it is the main mineralocorticoid hormone made in zona glomerulosa of the adrenal cortex in the adrenal gland. It works on distal tubules and collecting ducts of our kidneys. It is essential for the reabsorption of water and conservation of sodium ions. Aldosterone is released to the blood in response to increased K in serum, decreased Na in serum and low renal perfusion.
Aldosterone increases the activity of sodium and potassium pumps and influences the reabsorption of sodium and excretion of potassium. So, this, in turn, influences the water retention or loss, blood pressure and blood volume. Moreover, aldosterone is a part of the renin–angiotensin–aldosterone system.
What are the Similarities Between ADH and Aldosterone?
- ADH and aldosterone work mainly in the collecting duct of our kidneys.
- They are responsible for the water balance in our body.
- Both hormones increase the water reabsorption in the kidneys collecting ducts.
What is the Difference Between ADH and Aldosterone?
ADH is a peptide hormone made in hypothalamus while aldosterone is a steroid hormone made in the adrenal cortex. So, this is the key difference between ADH and aldosterone. Besides, the ADH is a peptide composed of nine amino acids, while the aldosterone is a steroid made of cholesterol. Therefore, this is the basic structural difference between ADH and aldosterone. Functionally, the main function of ADH is increasing water permeability of the collecting duct, while the main function of aldosterone is increasing of active reabsorption of Na+ in the collecting duct.
Moreover, ADH works via increasing the water permeability by opening pores in kidney epithelial cells, while aldosterone works via increasing the activity of sodium pumps. Also, another difference between ADH and aldosterone is the release of each hormone. ADH is released in response to increased blood osmolality or to a decrease in blood volume while aldosterone is released in response to increased serum K, decreased serum Na, or low renal perfusion.
Summary – ADH vs Aldosterone
ADH and aldosterone are two types of hormones that increase water reabsorption in kidneys. Both act on collecting ducts of nephrons. ADH is a peptide hormone made in the hypothalamus. In contrast, aldosterone is a steroid hormone made in adrenal glands. This is the key difference between ADH and aldosterone. Moreover, ADH is released into the blood in response to increased blood osmolality and decreased blood volume while aldosterone is released into the blood in response to increased serum K, decreased serum Na and low renal perfusion. ADH works on increasing the water permeability of the collecting ducts while aldosterone works on increasing the activity of sodium/potassium pumps.
1. “2709 ADH” By OpenStax College – Anatomy & Physiology, Connexions Web site, Jun 19, 2013 (CC BY 3.0) via Commons Wikimedia
2. “Aldosterone-2D-skeletal” By Image:Aldosterone-2D-skeletal.png by Ben Mills, vectorized by Fvasconcellos (talk · contribs) – Vector version of Image:Aldosterone-2D-skeletal.png. (Public Domain) via Commons Wikimedia