Kidneys

Definition

Kidneys are vital organs in the body that play a critical role in filtering waste products from the blood and regulating fluid balance, electrolyte levels, and blood pressure. These bean-shaped organs are part of the excretory system and contribute to maintaining homeostasis by producing urine, which removes toxins and excess substances from the bloodstream.

5 Must Know Facts For Your Next Test

1. The kidneys filter approximately 50 gallons of blood daily, producing about 1 to 2 quarts of urine to eliminate waste.
2. Each kidney contains around a million nephrons, which are essential for filtering blood and maintaining fluid balance.
3. The kidneys also help regulate blood pressure through the renin-angiotensin-aldosterone system by adjusting blood volume and vascular resistance.
4. Kidneys produce hormones like erythropoietin, which stimulates red blood cell production in the bone marrow, and calcitriol, which helps regulate calcium levels.
5. The kidneys can adapt to changes in hydration and electrolyte levels, ensuring that homeostasis is maintained even when dietary intake fluctuates.

Review Questions

• Explain how nephrons function within the kidneys to maintain homeostasis in the body.
  • Nephrons are the functional units of the kidneys that filter blood and regulate its composition to maintain homeostasis. Each nephron consists of a glomerulus for filtration and a tubule for reabsorption and secretion. Through these processes, nephrons remove waste products and excess substances from the bloodstream while reclaiming essential nutrients and water. This balance is crucial for regulating fluid levels, electrolytes, and overall blood pressure in the body.
• Discuss the role of hormones produced by the kidneys in regulating bodily functions.
  • The kidneys produce several important hormones that play key roles in bodily regulation. Erythropoietin stimulates red blood cell production in response to low oxygen levels, enhancing oxygen transport throughout the body. Calcitriol, the active form of vitamin D produced by the kidneys, helps regulate calcium and phosphate levels essential for bone health. Additionally, through the renin-angiotensin-aldosterone system, the kidneys influence blood pressure by adjusting blood volume and vascular resistance.
• Analyze how kidney dysfunction can affect homeostasis and overall health.
  • Kidney dysfunction can significantly disrupt homeostasis and impact overall health by impairing waste removal and fluid regulation. When kidneys fail to filter effectively, toxins accumulate in the bloodstream, leading to uremia, which can cause nausea, fatigue, and other severe symptoms. Fluid imbalance may lead to hypertension or edema due to excessive water retention. Additionally, disrupted hormone production can result in anemia from decreased erythropoietin or weakened bones from poor calcium regulation. Overall, kidney health is crucial for maintaining systemic balance and preventing serious health complications.

Related terms

nephrons:

Nephrons are the functional units of the kidneys, responsible for filtering blood and forming urine through processes of filtration, reabsorption, and secretion.

ureters: Ureters are tubes that carry urine from the kidneys to the bladder, playing an essential role in the excretory system.

renal cortex:

The renal cortex is the outer region of the kidney where the nephrons are located, involved in filtering blood and beginning urine formation.