Urine Production and Regulation

Urine Production Process

• Filtration: Blood from renal arteries enters the kidneys, where it's filtered through the glomeruli, a cluster of capillaries, to remove waste and excess fluids.
• Reabsorption: The filtered fluid, now called tubular fluid, passes through the renal tubules, where necessary substances like glucose, amino acids, and ions are reabsorbed into the bloodstream.
• Secretion: The renal tubules also secrete waste products, such as urea, creatinine, and other ions, into the tubular fluid.

Regulation of Urine Production

• Antidiuretic hormone (ADH): Released by the hypothalamus, ADH stimulates the kidneys to reabsorb more water, decreasing urine production.
• Aldosterone: A hormone produced by the adrenal glands, aldosterone regulates the amount of water reabsorbed by the kidneys, influencing urine production.

Factors Affecting Urine Production

• Blood pressure: Increased blood pressure increases glomerular filtration rate, leading to increased urine production.
• Hydration level: Dehydration stimulates ADH release, reducing urine production, while overhydration decreases ADH release, increasing urine production.
• Hormonal changes: Hormonal fluctuations, such as those experienced during pregnancy, can affect urine production.

Urine Composition

• Urea: The primary waste product in urine, produced from protein breakdown.
• Water: The majority of urine composition, with a normal range of 1-2 liters per day.
• Electrolytes: Urine contains varying amounts of electrolytes, such as sodium, potassium, and chloride.
• Pigments: Urobilin and urochromes give urine its yellow color.