Tests & Procedures Index



Digestive and Liver Disorders Overview

What is digestion?

Food and drink must be changed into smaller molecules of nutrients to be absorbed into the blood and carried to cells throughout the body. Digestion is the process by which food and drink are broken down into smaller parts so that the body can use them to build and nourish cells, and to provide energy.

Illustration of the anatomy of the digestive system, adult
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How does the digestive process work?

Digestion involves:

  • The mixing of food with digestive juices.
  • The movement of food through the digestive tract.
  • A chemical breakdown of large molecules of food into smaller molecules so the body can use them to nourish cells and provide energy.

Digestion begins in the mouth, where food and drink is taken in, and is completed in the small intestine.

What is included in the digestive system?

The digestive tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus, consisting of the following:

  • Mouth
  • Esophagus
  • Stomach
  • Small intestine
  • Large intestine
  • Rectum
  • Anus

Organs that help with digestion, but are not part of the digestive tract, include the following:

  • Tongue
  • Glands in the mouth that make saliva
  • Pancreas
  • Liver
  • Gallbladder

Parts of other organ systems, like nerves and blood, also play a major role in the digestive process.

How does food move through the digestive system?

In a wave-like movement, called peristalsis, muscles propel food and liquid along the digestive tract.

What changes occur in the digestive system during pregnancy?

Hormones of pregnancy can affect the digestive system. The hormone progesterone, which causes smooth muscle relaxation, often causes relaxation and slowing of digestion in the stomach and the small and large intestines. The gallbladder is also affected with delayed emptying that can increase the chances of gallstone formation. Many of the digestive discomforts of pregnancy, such as morning sickness (nausea or vomiting), constipation, and heartburn are all related to the relaxed tone and slowed action of the digestive system.

The growing uterus itself can affect the digestive system. As the uterus grows, it can compress or even obstruct some of the parts of the digestive tract. This can lead to slowed movement of food and constipation. Increasing fluids, regular exercise, and increasing the fiber in your diet are some of the ways to prevent constipation. Always consult your health care provider before taking any medication for this condition.

Many women have appetite changes in pregnancy, including increased hunger, decreased appetite, cravings, aversions, nausea, and vomiting. A few women develop pica, a rare craving to eat substances other than food, such as dirt, clay, or coal. The craving may indicate a nutritional deficiency.

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Last reviewed: 4/11/2012