The liver is a large organ in the right upper part of the abdomen. It performs a range of complex and important functions that affect all body systems. Some of the specific functions of the liver include:

• Controlling the amounts of sugar (glucose), protein, and fat entering the bloodstream.
• Removing bilirubin, ammonia, and other toxins from the blood. Bilirubin is a by-product of the breakdown of hemoglobin from red blood cells.
• Processing most of the nutrients absorbed by the intestines during digestion and converting those nutrients into forms that can be used by the body. The liver also stores some nutrients, such as vitamin A, iron, and other minerals.
• Producing cholesterol, substances that help blood clot, bile, and certain important proteins, such as albumin.
• Breaking down (metabolizing) alcohol and many drugs.

The intestine (bowel) is the long, winding, tube that is part of the digestive tract. The intestine helps to process food, extract and absorb nutrients and water, and eliminate waste.

The intestine is divided into two main parts:

• The small intestine (small bowel) receives food from the lower end of the stomach and continues to digest it before passing it into the large intestine. The small intestine is about 6 m (20 ft) long.
• The large intestine (large bowel) absorbs chemicals (such as sodium and chloride), nutrients, and water from the digested food. It also prepares waste (stool) to be expelled from the body. The large intestine is also called the colon. It is about 1.5 m (5 ft) long.

The kidneys are two bean-shaped organs located on either side of the spine, at the small of the back. The kidneys filter wastes from the blood and help balance water, salt, and mineral levels in the blood.

Wastes filtered out of the blood are carried out of the body as urine. Urine flows through tubes (ureters) to the bladder, where it is stored until a person is ready to urinate. The waste and urine then leave the bladder and exit the body through a tube called the urethra.