The human excretory system is a fascinating network of organs responsible for removing waste products and maintaining the body’s internal balance. Let’s delve into its structure and functions:

Organs of the Human Excretory System:

1. Kidneys:

   • These bean-shaped organs, located on either side of the vertebral column, filter blood and produce urine.
   • Each kidney contains around one million nephrons, which are the functional units responsible for waste removal.
   • The renal cortex and medulla house these nephrons.
   • The kidneys also play a role in regulating blood pressure and producing hormones.

2. Nephrons:

   • Nephrons are the microscopic structures within the kidneys.
   • Each nephron consists of two main parts:
     • Renal Corpuscle: Includes the glomerulus (a tuft of capillaries) and the glomerular capsule (Bowman’s capsule).
     • Renal Tubule System:
       • Proximal Tubule: Responsible for reabsorbing essential molecules (e.g., glucose, water).
       • Nephron Loop (Loop of Henle): Involved in concentrating urine by creating a hypertonic environment.
       • Distal Tubule: Further fine-tunes urine composition.
       • Collecting Ducts: Collect urine from multiple nephrons and transport it to the renal pelvis.

3. Urinary Bladder:

   • Temporarily stores urine until it is expelled from the body through the urethra.

4. Ureters:

   • Tubes that transfer liquid waste (urine) from the kidneys to the urinary bladder.
   • Ureterovesical valves prevent urine from flowing back into the kidneys.

5. Skin:

   • Excretes waste products through sweat glands.
   • Sweat contains salt, excess oils, and other unnecessary substances.

6. Lungs:

   • Expel carbon dioxide (a waste product) during exhalation.

7. Liver (Accessory Organ):

   • Detoxifies harmful substances and processes metabolic waste.
   • Converts ammonia (from protein breakdown) into less harmful urea, which is excreted by the kidneys.

8. Gallbladder (Accessory Organ):

   • Stores bile produced by the liver to aid in fat digestion.

Function of the Excretory System:

• Urine Production: Maintains fluid and electrolyte balance, acid-base balance, and blood pressure.
• Waste Removal: Eliminates nitrogenous wastes (e.g., urea) and excess water.
• Homeostasis: Ensures stability within the body despite changes in food intake and environmental conditions.