digestion

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References & Edit History Quick Facts & Related Topics

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human digestive system

The chemistry of digestion: How food is broken down

Why do people feel full after a big meal?

Digestive vacuole

Why can coffee act as a laxative?

Why does your stomach make noise?

The small and large intestines animated

Major organs of the human digestive system. Food taken in by the mouth is guided by the tongue as it is sheared and ground by the teeth. The bolus of chewed food is moistened and lubricated with saliva secreted by the salivary glands. Enzymes in the saliva begin the breakdown of starches. The epiglottis, a flap of tissue, prevents food from the pharynx from entering the larynx during swallowing. Muscles in the esophagus wall contract in waves to move the food to the stomach. Gastric juices secreted by the stomach contain a mixture of substances (including enzymes and hydrochloric acid) that break down the food into a semiliquid mass called chyme. The chyme passes into the small intestine, where food molecules are broken down into sugars, amino acids, and fatty acids. These useful substances are absorbed into the bloodstream as the food passes through the duodenum, jejunum, and ileum. The pancreas secretes digestive enzymes into the duodenum. The liver secretes bile salts that make insoluble fats entering the small intestine water-soluble and vulnerable to enzymatic action. Excess bile salts are stored in the gallbladder. The large intestine (colon) serves to remove water and electrolytes from the digested chyme and to compact and store undigestible material, called feces. Fecal matter is moved by muscular contractions into the rectum and expelled from the anus.

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digestion: Media

biology

Videos

The chemistry of digestion: How food is broken down

The chemistry of digestion: How food is broken down

Using chemistry to explain how humans digest carbohydrates, proteins, and fats.

Video: © American Chemical Society (A Britannica Publishing Partner)

Why do people feel full after a big meal?

Why do people feel full after a big meal?

Learn why eating large meals can cause bloating, heartburn, and discomfort.

Video: © American Chemical Society (A Britannica Publishing Partner)

Why can coffee act as a laxative?

Why can coffee act as a laxative?

Understanding the potential laxative effects of coffee.

Video: © American Chemical Society (A Britannica Publishing Partner)

Why does your stomach make noise?

Why does your stomach make noise?

Learn why the human stomach rumbles.

Video: Contunico © ZDF Studios GmbH, Mainz

The small and large intestines animated

The small and large intestines animated

Most of the digestive process occurs in the small intestine, which channels water...

Video: Created and produced by QA International. © QA International, 2010. All rights reserved. www.qa-international.com

Images

human digestive system

human digestive system

The human digestive system as seen from the front.

Encyclopædia Britannica, Inc.

Digestive vacuole

Digestive vacuole

The role of lysosomes in intracellular digestionDigestion...

Encyclopædia Britannica, Inc.

Major organs of the human digestive system. Food taken in by the mouth is guided by the tongue as it is sheared and ground by the teeth. The bolus of chewed food is moistened and lubricated with saliva secreted by the salivary glands. Enzymes in the saliva begin the breakdown of starches. The epiglottis, a flap of tissue, prevents food from the pharynx from entering the larynx during swallowing. Muscles in the esophagus wall contract in waves to move the food to the stomach. Gastric juices secreted by the stomach contain a mixture of substances (including enzymes and hydrochloric acid) that break down the food into a semiliquid mass called chyme. The chyme passes into the small intestine, where food molecules are broken down into sugars, amino acids, and fatty acids. These useful substances are absorbed into the bloodstream as the food passes through the duodenum, jejunum, and ileum. The pancreas secretes digestive enzymes into the duodenum. The liver secretes bile salts that make insoluble fats entering the small intestine water-soluble and vulnerable to enzymatic action. Excess bile salts are stored in the gallbladder. The large intestine (colon) serves to remove water and electrolytes from the digested chyme and to compact and store undigestible material, called feces. Fecal matter is moved by muscular contractions into the rectum and expelled from the anus.

Major organs of the human digestive system. Food taken in by the mouth is guided...

© Merriam-Webster Inc.

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