Nephron Structure and Function

Nephron Structure

• Definition: Nephrons are the functional units of the kidney responsible for filtering blood and producing urine.

• Components of Nephron:

  1. Renal Corpuscle:

     • Glomerulus: A network of capillaries where filtration occurs. Blood pressure forces water and solutes out of the blood.
     • Bowman's Capsule: A cup-like structure that encases the glomerulus and collects the filtrate.

  2. Renal Tubule:

     • Proximal Convoluted Tubule (PCT):
       • First segment after Bowman's capsule.
       • Reabsorbs nutrients (glucose, amino acids), ions (Na+, Cl-), and water from the filtrate.
     • Loop of Henle:
       • Has a descending limb (permeable to water) and an ascending limb (permeable to salts).
       • Establishes concentration gradient in the kidney.
     • Distal Convoluted Tubule (DCT):
       • Further modifies filtrate, reabsorbing ions and water based on body needs.
       • Site of secretion for certain ions and substances (e.g., potassium, hydrogen ions).

  3. Collecting Duct:

     • Receives filtrate from multiple nephrons.
     • Final site for water reabsorption, influenced by hormones (e.g., ADH).

• Types of Nephrons:

  1. Cortical Nephrons:
     • Located primarily in the kidney cortex.
     • Shorter loops of Henle.
  2. Juxtamedullary Nephrons:
     • Located near the medulla.
     • Longer loops of Henle, essential for concentrating urine.

• Juxtaglomerular Apparatus:

  • A specialized structure formed by the distal convoluted tubule and afferent arterioles.
  • Regulates blood pressure and filtration rate through the secretion of renin.

• Functionality:

  • Each nephron filters blood, reabsorbs essential substances, and secretes wastes into urine.
  • Approximately 1 million nephrons per kidney, ensuring efficient waste removal and homeostasis.

Nephron Structure

• Nephrons are the kidney's functional units, critical for blood filtration and urine production.

Components of Nephron

• Renal Corpuscle

  • Glomerulus: A capillary network where blood filtration occurs, facilitated by blood pressure that pushes water and solutes out.
  • Bowman's Capsule: A cup-like structure surrounding the glomerulus, responsible for collecting the filtrate.

• Renal Tubule

  • Proximal Convoluted Tubule (PCT):
    • First segment post-Bowman's capsule.
    • Reabsorbs vital nutrients (such as glucose and amino acids), ions (Na+, Cl-), and water.
  • Loop of Henle:
    • Comprises a descending limb (water-permeable) and an ascending limb (salt-permeable).
    • Establishes an osmotic gradient critical for urine concentration.
  • Distal Convoluted Tubule (DCT):
    • Further adjusts filtrate composition, reabsorbing ions and water based on physiological demands.
    • Secretes specific ions and substances like potassium and hydrogen ions.

• Collecting Duct

  • Receives filtrate from multiple nephrons.
  • Serves as the final site for water reabsorption, influenced by hormones like antidiuretic hormone (ADH).

Types of Nephrons

• Cortical Nephrons:
  • Predominantly located in the kidney cortex.
  • Feature shorter loops of Henle.
• Juxtamedullary Nephrons:
  • Positioned near the medulla.
  • Contain longer loops of Henle, crucial for urine concentration.

Juxtaglomerular Apparatus

• A structure formed by the distal convoluted tubule and afferent arterioles.
• Plays a key role in regulating blood pressure and filtration rate by secreting renin.

Functionality

• Each nephron filters blood, reabsorbs essential substances, and secretes waste into urine.
• The human kidney contains approximately 1 million nephrons, ensuring effective waste management and homeostasis.

This quiz covers the structure and components of nephrons, the functional units of the kidney. You will explore the renal corpuscle, including glomerulus and Bowman's capsule, and the renal tubule's various parts like the PCT, Loop of Henle, and DCT. Test your understanding of how these structures contribute to kidney function.