Overview of the Digestive System and Its Functions

Mouth

Main organ of the digestive system where ingestion occurs.

Pharynx

Passage that connects the mouth to the esophagus.

Esophagus

Tube that carries food from the pharynx to the stomach.

Stomach

Organ that mixes food with gastric juices for digestion.

Small intestine

Organ where most chemical digestion and nutrient absorption occurs; consists of duodenum, jejunum, and ileum.

Large intestine

Organ that absorbs water and forms feces; includes cecum, colon, rectum, and anal canal.

Anus

Opening at the end of the digestive tract for excretion.

Teeth & tongue

Accessory organs that aid in mechanical digestion.

Salivary glands

Accessory organs that produce saliva to aid in digestion.

Liver

Accessory organ that produces bile and processes nutrients.

Gallbladder

Accessory organ that stores and concentrates bile.

Pancreas

Accessory organ that produces digestive enzymes and hormones.

Mucosa

Inner layer of the digestive tract wall responsible for secretion, absorption, and protection.

Submucosa

Layer of connective tissue that supports the mucosa and contains blood vessels, lymphatics, and nerves.

Muscularis externa

Layer of smooth muscle responsible for peristalsis and segmentation.

Serosa

Outermost protective layer of the digestive tract.

Ingestion

Taking food into the mouth.

Secretion

Release of water, acid, buffers, and enzymes into the GI tract.

Digestion

Breakdown of food into smaller molecules (mechanical & chemical).

Absorption

Transport of nutrients into the blood or lymph.

Excretion (defecation)

Elimination of indigestible substances and waste as feces.

Salivary Amylase

Enzyme produced by salivary glands that begins the chemical digestion of carbohydrates.

Segmentation

Local mixing contractions in the small intestine with no net movement.

Peristalsis

Wave-like muscle contractions that move food along the GI tract.

Mastication

Chewing, a form of mechanical digestion.

Deglutition

Swallowing process.

Defecation

Elimination of feces through the anus.

Esophageal Hiatus

A hole in the diaphragm through which the esophagus passes.

Epiglottis Importance

Prevents food and liquid from entering the trachea during swallowing.

Stomach Regions

Includes cardia, fundus, body, and pylorus.

Gastric Gland Cells

Cells in the stomach that secrete hydrochloric acid, pepsinogen, and mucus.

Three Parts of the Small Intestine

Duodenum, jejunum, and ileum, each with specific functions in digestion and absorption.

Where Most Nutrient Absorption Occurs

Primarily in the jejunum of the small intestine.