Structure and Function of Digestive System

Gastrointestinal Tract

Long tube that transports food during processing, includes esophagus, stomach, intestines, and rectum

Accessory Structures

Teeth, tongue, salivary glands, liver, gallbladder, and pancreas

Saliva

Water with mucus, sodium, bicarbonate, chloride, potassium, and salivary amylase, initiates break down of carbs

Peristalsis

Coordinated contraction and relaxation of muscle layers to propel food

Motilin

Hormone that increases peristalsis

Secretin

Hormone that decreases peristalsis

Cephalic Secretions

Gastric secretions stimulated by the thought, smell, and taste of food

Gastric Secretions

Gastric secretions stimulated by distention of the stomach

Intestinal Secretions

Gastric secretions stimulated by histamines and digested protein

Stomach Acid

HCl, secreted by parietal cells, dissolves food, acts as a bactericide, and converts pepsinogen to pepsin

Pepsin

Proteolytic enzyme secreted by chief cells

Intestinal Motility

Movement of small intestine that facilitates digestion and absorption

Haustral Segmentation

Localized rhythmic contractions of circular smooth muscle in the intestines

Peyer Patches

Collections of lymphocytes, plasma cells, and macrophages that produced IgA

Kupffer Cells

Tissue macrophages important for healing liver injuries

Bile

Alkaline fluid that contains bile salts, secreted by liver

Unconjugated Bilirubin

Waste product of Hb breakdown that is taken up by the liver

Urobilirubin

Colorless byproduct of bilirubin reduction