Excretion in Human Beings
Excretion is the process by which metabolic waste products and harmful substances are eliminated from the body. In human beings, the excretory system plays a crucial role in maintaining homeostasis by removing waste products while regulating the body's water and electrolyte balance.

Organs Involved in Excretion
1. Kidneys: The kidneys are the main excretory organs in humans. They filter waste products from the blood to form urine.
2. Ureters: These tubes transport urine from the kidneys to the urinary bladder.
3. Urinary Bladder: The bladder stores urine until it is expelled from the body.
4. Urethra: The urethra is the tube through which urine is expelled from the body.

Process of Excretion
1. Filtration: Blood is filtered in the kidneys to remove waste products and excess substances.
2. Reabsorption: Essential substances like water, glucose, and ions are reabsorbed back into the blood.
3. Secretion: Additional waste products are actively secreted into the urine.
4. Excretion: The urine is then excreted from the body through the urethra.

Neat Labelled Diagram of Excretory System
[Please refer to the diagram below]
The diagram should include labels for the kidneys, ureters, urinary bladder, and urethra. It should clearly show the flow of urine from the kidneys to the bladder and out of the body through the urethra. The diagram should be neat, well-labelled, and easy to understand.