Kidney

Definition

The kidney is a vital organ in the urinary system responsible for filtering blood, removing waste products, and regulating fluid balance and electrolytes. It plays a crucial role in maintaining homeostasis, as it not only filters toxins but also controls blood pressure and red blood cell production through the secretion of hormones like erythropoietin. Each kidney contains approximately one million functional units called nephrons, which are essential for performing the organ's complex functions.

5 Must Know Facts For Your Next Test

1. Kidneys filter approximately 50 gallons (around 200 liters) of blood daily to produce about 1 to 2 quarts of urine.
2. The kidneys help regulate blood pressure through the renin-angiotensin-aldosterone system, which adjusts blood volume and vascular resistance.
3. Kidneys also maintain acid-base balance by excreting hydrogen ions and reabsorbing bicarbonate from urine.
4. Each kidney contains about one million nephrons that play a crucial role in filtering blood and forming urine.
5. Kidney function can be affected by diseases such as diabetes and hypertension, leading to chronic kidney disease.

Review Questions

• How do the structural features of the nephron contribute to its function in the kidney?
  • The nephron's structure is specifically designed to efficiently filter blood and form urine. It consists of a glomerulus for initial filtration and a renal tubule where reabsorption and secretion take place. The tubule's various segments (proximal tubule, loop of Henle, distal tubule) have specialized cells that allow for selective transport of water, ions, and nutrients, ensuring that essential substances are reabsorbed into the bloodstream while waste products are excreted.
• Discuss the role of kidneys in maintaining homeostasis within the body.
  • Kidneys play a critical role in homeostasis by regulating fluid balance, electrolyte levels, and blood pressure. They filter waste from the blood while reabsorbing vital nutrients and ions like sodium, potassium, and calcium. Additionally, they help maintain acid-base balance by controlling hydrogen ion secretion and bicarbonate reabsorption. By adjusting urine output based on hydration status, kidneys ensure that the internal environment remains stable despite external changes.
• Evaluate the impact of chronic kidney disease on overall health and body systems.
  • Chronic kidney disease (CKD) leads to a gradual loss of kidney function over time, which can have widespread effects on overall health. As kidneys fail to filter waste effectively, toxins build up in the bloodstream, resulting in symptoms such as fatigue, swelling, and anemia. Furthermore, CKD disrupts fluid balance and electrolyte levels, potentially leading to complications like cardiovascular disease and bone disorders. The systemic impact highlights the importance of early detection and management to preserve kidney function and maintain overall health.

Related terms

nephron: The nephron is the functional unit of the kidney, consisting of a glomerulus and a renal tubule, where filtration, reabsorption, and secretion occur.

glomerulus:

The glomerulus is a network of capillaries located at the beginning of each nephron where blood filtration begins.

ureter: The ureter is a tube that carries urine from the kidney to the bladder for storage before excretion.