How is the amount of urine produced regulated

About 180 litres of fluid is collected in human nephrons daily after filtration. But most of this water is reabsorbed by the tubule. The amount of urine produced is regulated by the process of re-absorption. If input of water is more, then there is less re-absorption of water. When water is to be conserved in the body, reabsorption increases. This is called Osmoregulation.

Several hormones have specific, important roles in regulating kidney function. They act to stimulate or inhibit blood flow. Some of these are endocrine, acting from a distance, whereas others are paracrine, acting locally. • Water levels in the body are controlled by antidiuretic hormone (ADH), which is produced in the hypothalamus and triggers the reabsorption of water by the kidneys. Underproduction of ADH can cause diabetes insipidus. • Aldosterone, a hormone produced by the adrenal cortex of the kidneys, enhances Na reabsorption from the extracellular fluids and subsequent water reabsorption by diffusion. • The renin-angiotensin-aldosterone system is one way that aldosterone release is controlled. Antidiuretic hormone (ADH) ADH, a 9-amino acid peptide released by the posterior pituitary – in brain, works to do the exact opposite. It promotes the recovery of water, decreases urine volume, and maintains plasma osmolarity and blood pressure. It does so by stimulating the movement of aquaporin proteins into the apical cell membrane of principal cells of the collecting ducts to form water channels. A proper water balance in the body is important to avoid dehydration or over-hydration. The water concentration of the body is monitored by osmoreceptors in the hypothalamus, which detect the concentration of electrolytes in the extracellular fluid. The concentration of electrolytes in the blood rises when there is water loss caused by excessive perspiration, inadequate water int...

ADH is also called arginine vasopressin. It’s a hormone made by the ADH constantly regulates and balances the amount of water in your blood. Higher water concentration increases the volume and pressure of your blood. Osmotic sensors and baroreceptors work with ADH to maintain water metabolism. Osmotic sensors in the hypothalamus react to the concentration of particles in your blood. These particles include molecules of The normal range for ADH is 1-5 picograms per milliliter (pg/mL). Normal ranges can vary slightly among different laboratories. ADH levels that are too low or too high can be caused by a number of different problems . ADH deficiency Too little ADH in your blood may be caused by compulsive water drinking or A rare water Common symptoms include excessive urination, which is called People with central diabetes insipidus are often extremely tired because their sleep is frequently interrupted by the need to urinate. Their urine is clear, odorless, and has an abnormally low concentration of particles. Central diabetes insipidus can lead to severe This disorder is not related to the more common Excess ADH When there’s too much ADH in your blood, syndrome of inappropriate ADH (SIADH) may be the cause. If the condition is acute, you may have a Increased ADH is associated with: • • • • • • • systemic cancers that produce ADH • • • • acute intermittent • • • • • Dehydration, brain trauma, and surgery can also cause excess ADH. Nephrogenic diabetes insipidus is not rela...

The amount of urine largely depends on the amount of water reabsorbed. The amount of water reabsorbed by the nephron tubule depends on. (i) The amount of water in the body . When water is abundant in the body tissues, large quantities of dilute urine is excreted out. When water is less in quantities in the body tissues, a small quantity of concentrated, with less water content, is excreted. (ii) The amount of dissolved wastes, especially nitrogenous wastes, like urea and uric acid and salts in the body. When there is more quantity of dissolved wastes in the body, more quantity of water is required to excrete them. So, the amount of urine produced increases. When the amount of these substances in the body is less then less urine is produced. (iii) The amount of urine produced is also regulated by certain hormones which control the movement of water and Na +ions into and out of the nephrons.

Water Balance On a typical day, the average adult will take in about 2500 mL (almost 3 quarts) of aqueous fluids. Although most of the intake comes through the digestive tract, about 230 mL (8 ounces) per day is generated metabolically, in the last steps of aerobic respiration. Additionally, each day about the same volume (2500 mL) of water leaves the body by different routes; most of this lost water is removed as urine. The kidneys also can adjust blood volume though mechanisms that draw water out of the filtrate and urine. The kidneys can regulate water levels in the body; they conserve water if you are dehydrated, and they can make urine more dilute to expel excess water if necessary. Water is lost through the skin through evaporation from the skin surface without overt sweating and from air expelled from the lungs. This type of water loss is called insensible water loss because a person is usually unaware of it. Regulation of Water Intake: Osmolality is the ratio of solutes in a solution to a volume of solvent in a solution. Plasma osmolality is thus the ratio of solutes to water in blood plasma. A person’s plasma osmolality value reflects his or her state of hydration. A healthy body maintains plasma osmolality within a narrow range, by employing several mechanisms that regulate both water intake and output. Figure 1. Click to view a larger image. The thirst response begins when osmoreceptors detect a decrease in water levels in the blood. Drinking water is considered...