Kidney

Definition

The kidney is a vital organ in vertebrates that plays a key role in filtering blood, removing waste products, and regulating fluid and electrolyte balance. It ensures homeostasis by maintaining osmotic balance, regulating blood pressure, and controlling the pH levels of the blood. The kidneys are essential for the process of osmoregulation, allowing organisms to adapt to varying environmental conditions.

5 Must Know Facts For Your Next Test

1. Each human kidney contains approximately one million nephrons that are responsible for filtering blood.
2. The kidneys help regulate the osmotic concentration of the body fluids by adjusting water reabsorption and electrolyte balance.
3. Hormones like aldosterone and antidiuretic hormone (ADH) influence kidney function by regulating sodium and water reabsorption.
4. Kidneys also play a role in acid-base balance by excreting hydrogen ions and reabsorbing bicarbonate from urine.
5. The renal cortex and renal medulla are two distinct regions of the kidney, each with specific functions related to filtration and concentration of urine.

Review Questions

• How do the kidneys contribute to osmoregulation in the body?
  • The kidneys contribute to osmoregulation by filtering blood to remove waste while selectively reabsorbing water and electrolytes. This filtration occurs within the nephron, where water reabsorption can be adjusted based on the body's hydration status. Hormones like ADH signal the kidneys to retain more water when dehydrated, thus helping maintain osmotic balance.
• Discuss the roles of hormones such as aldosterone and ADH in kidney function and their impact on fluid balance.
  • Aldosterone and ADH play crucial roles in kidney function by regulating sodium and water reabsorption. Aldosterone increases sodium reabsorption in the distal convoluted tubule, leading to increased water retention, while ADH promotes water reabsorption in the collecting ducts. Together, they help control blood volume and pressure, impacting overall fluid balance in the body.
• Evaluate how dysfunction of the kidneys can lead to systemic issues related to osmoregulation and homeostasis.
  • Dysfunction of the kidneys can severely disrupt osmoregulation and homeostasis, leading to conditions such as dehydration or fluid overload. When kidneys fail to filter waste properly or regulate electrolytes, it can result in imbalances that affect heart function, blood pressure, and acid-base status. Chronic kidney disease can also lead to complications like anemia and bone disease, highlighting the critical role kidneys play in maintaining overall health.

Related terms

Nephron: The basic structural and functional unit of the kidney, responsible for filtering blood and forming urine.

Osmoregulation: The process by which living organisms maintain the proper balance of water and electrolytes in their bodies.

Glomerulus: A network of capillaries in the nephron where blood filtration occurs, playing a critical role in urine formation.