1. Urea: Produced by the liver, urea is a nitrogenous waste product formed from the breakdown of proteins. It is filtered out of the blood by the kidneys and excreted in urine.

2. Carbon Dioxide (CO2): This is a waste product of cellular respiration and is produced by all cells in the body. It is transported in the blood to the lungs where it is exhaled.

3. Sweat: Produced by the sweat glands in the skin, sweat is primarily composed of water, but also contains salts, urea, and other waste products. Sweating helps to regulate body temperature.

4. Feces: While primarily undigested food matter, feces also contain waste products from the digestive system, including bile pigments from the liver and bacteria. It is formed in the large intestine and excreted through the anus.