Introduction:
The kidneys are vital organs responsible for various functions in the body, including the excretion of waste products. However, their work in waste elimination is supplemented by other organs that also play a role in excretion.
Answer:
D: Skin
Explanation:
The kidneys are not the only organs involved in excretion. Other organs, such as the skin, also contribute to eliminating waste products from the body. Here's how each organ helps in the excretion process:
1. Kidneys:
- The kidneys filter waste products, excess water, and toxins from the blood to produce urine.
- They help maintain the body's fluid and electrolyte balance.
- The kidneys also regulate blood pressure and produce hormones involved in red blood cell production.
2. Skin:
- The skin plays a crucial role in excretion through the process of sweating.
- Sweat glands in the skin excrete waste products such as urea, salts, and water.
- Sweating helps regulate body temperature and removes toxins from the body.
3. Lungs:
- While the primary function of the lungs is respiration, they also contribute to excretion.
- During respiration, carbon dioxide, which is a waste product of metabolism, is eliminated from the body.
- Oxygen is taken in during inhalation, and carbon dioxide is expelled during exhalation.
4. Liver:
- The liver is involved in various metabolic processes, including the breakdown and elimination of waste products.
- It metabolizes toxins and drugs, converting them into less harmful substances that can be excreted.
- The liver also produces bile, which helps eliminate waste products from the digestive system.
5. Large Intestine:
- While the large intestine is primarily responsible for absorbing water and electrolytes from undigested food, it also eliminates waste.
- It collects and compacts solid waste material, forming feces that are eventually eliminated through the rectum and anus.
Conclusion:
The kidneys are essential organs of excretion, but their work is supplemented by other organs like the skin, lungs, liver, and large intestine. Each of these organs contributes to eliminating waste products and maintaining overall body homeostasis.

Kidney helps in the filtration of blood. Liver supplement the fiction of the kidney by the formation of urea by a cyclic process called as urea cycle of A Ornithine cycle Or knely Henseleit cycle. The amino acid that are not needed in the body are deminated by an enzyme oxidase producing ammonia NH3. Ammonia, Hung toxic , is quickly change to urea.