The Gastrointestinal System

The Gastrointestinal System

Also referred to as the digestive system. It basically is a long tube beginning at the mouth and ending at the anus with many different cell types and accessory organs that remove the nutrients needed by the body from foods and liquids leaving waste products to eventually be eliminated.

What does the Upper GI Tract contain

Oral Cavity, Pharynx, Esophagus, and Stomach.

Oral Cavity

This includes the lips, soft and hard palate, uvula, tongue, soft tissues, dental arches, teeth primary and permanent dentition and salivary glands secreting saliva.

Pharynx

The passageway for respiration and digestion. It plays a role in deglutition, or swallowing.

Esophagus

A long muscular tube that serves as a passageway from the pharynx to the stomach.

Stomach

This sac-like organ receives food from the esophagus for digestion.

What does the Lower GI Tract contain?

Small intestine and large intestine.

Small Intestine

This long tube extends from the pyloric sphincter of the stomach to the large intestine. It is divided into the duodenum, the jejunum, and ileum.

Large Intestine

This tube extends from the end of the small intestine to the anus. The major divisions are the cecum, colon, rectum, and anus.

What are the three accessory organs?

Liver, Gallbladder, and Pancreas.

Liver

This large organ removes toxins from the blood and helps turn food into fuel and nutrients.

Gallbladder

This pear-shaped organ is located under the liver and connects via small ducts. It stores bile formed by the liver.

Pancreas

This soft, oblong gland is located behind the stomach. It secrets pancreatic juices to aid digestion which it secretes into the pancreatic duct, into the bile duct, and into the duodenum.

Digestion

The process by which complex foods are broken down into nutrients in forms the body can use.

Metabolism

Refers to all of the processes involved in the body’s use of nutrients.

Anabolism

The building up of body cells and substances from nutrients.

Catabolism

The breaking down of body cells or substances, releasing energy and carbon dioxide.

Absorption

This is the process by which completely digested nutrients are transported to the cells throughout the body.

Mastication

This the technical term for chewing, breaking food down into smaller pieces and mixing it with saliva. It prepares to be swallowed.

Deglutition

Technical term for swallowing.

Peristalsis

This is the series of wave-like contractions of the smooth muscles in a single direction that moves the food forward into the digestive system.

What is the role of the stomach?

Secretes gastric juices that contain hydrochloric acid and digestive enzymes to break down food. The nutrients resulting in this breakdown enter the blood stream through the walls of the stomach.

What is the role of the small intestine

Breaks down food, absorbs over 90% of the body's nutrients and water, and moves remaining waste into the large intestine.

Large Intestine

Their role is to receive waste products of digestion and store them until they can be eliminated.

Defecation

Refers to the evacuation or emptying of the large intestine through the rectum and anus.

What is the role of the liver?

Secretes bile to help emulsify (breakdown) fats.

What is the role of the pancreas?

Secretes digestive juices to help break down proteins and carbohydrates.

Nutrients

Substances necessary for normal functioning of the body and include: Carbohydrates, Fats, Proteins, Vitamins, Minerals, and Water