Introduction The kidney is a vital organ responsible for maintaining homeostasis in the body. It plays a crucial role in filtering waste products and excess fluids from the blood. The kidney also helps regulate blood pressure and electrolyte balance.
Filtration The primary function of the kidney is to filter waste products and toxins from the blood. It does this through a complex process called glomerular filtration in the nephrons. Small molecules like water, electrolytes, and waste products are filtered into the renal tubules.
Reabsorption After filtration, the kidneys selectively reabsorb essential substances back into the bloodstream. This includes reabsorption of glucose, amino acids, and electrolytes like sodium and potassium. Reabsorption occurs primarily in the renal tubules, where the concentration of substances is regulated.
Secretion In addition to filtration and reabsorption, the kidney also secretes waste products into the urine. Substances like hydrogen ions and certain drugs are actively secreted from the blood into the tubules. Secretion helps eliminate additional waste and maintain the body's acid-base balance.
Hormone Production The kidney produces and releases hormones that regulate various functions in the body. One important hormone produced by the kidney is erythropoietin, which stimulates red blood cell production. The kidney also plays a role in converting vitamin D into its active form, promoting calcium absorption.
Regulation of Fluid Balance The kidney helps maintain the body's fluid balance by regulating urine concentration. It adjusts the amount of water reabsorbed and excreted based on the body's hydration needs. This process ensures that the body maintains proper hydration levels and prevents dehydration.
References "The Kidney: Structure and Function." National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), U.S. Department of Health and Human Services, 2017, www.niddk.nih.gov/health-information/kidney-disease/kidneys-how-they-work. Your second bullet Your third bullet