Chapter 16: Digestive System

Visceral peritoneum/Serosa

Serous membrane that covers the organs.

Parietal peritoneum

Serous membrane that lines the wall of the abdominal cavity.

Oral cavity or mouth

is the first part of the digestive tract. Bounded by lips and cheeks and contains the teeth and tongue.

Lips

muscular structures, formed mostly by the obicularis oris muscle. The outer surface of the lips are covered by the skin.

Functions of the Digestive System

1. Ingestion of food. Food and water enter the body through the mouth. 2. Digestion of food. During the process of digestion, food is broken down from complex particles to smaller molecules that can be absorbed. 3. Absorption of nutrients. Epithelial cells that line the lumen of the small intestine absorb the small molecules of nutrients that result from the digestive process. 4. Elimination of waste. Undigested material, such as fiber from food, plus waste products excreted into the digestive tract are eliminated in the feces.

Omental bursa.

Cavity or pocket, created by the greater omentum, from the long, double fold of mesentery that extends inferiorly from the stomach before looping back to the transverse colon. - Adipose tissue accumulates in the greater omentum, giving it a fat filled appearance that covers the anterior surface of the abdominal viscera.

Mesenteries

Connective tissue that hold organs of the abdominal cavity in place. - Two layers of serous membranes with a thin layer of loose connective tissue between them, attached to abdominal organs.

1. Mucosa

Consists of: - mucous epithelium - lamina propria (loose connective tissue) - muscularis mucosae (smooth muscle layer) Epithelium in the mouth, esophagus, and anus resists abrasion, and the epithelium in the stomach and intestine absorbs and secretes.

3. Muscularis

Inner layer of circular smooth muscle and outer layer of longitudinal smooth muscle. Another nerve plexus lies between the two muscle layers. Enteric nervous system: the nerve plexus of the submucosa and muscularis. - Control movement and secretion within the tract.

2. Submucosa

Just outside the mucosa. Thick layer of loose connective tissue containing nerves, blood vessels, and small glands. An extensive network of nerve cell processes forms a plexus. Autonomic nerves innervate this plexus.

Greater omentum

Mesentary connecting the greater curvature of the stomach to the transverse colon and posterior body.

Lesser omentum

Mesentery connecting the lesser curvature of the stomach to the liver and diaphragm.

Mesentery proper

Mesentery that attached the small intestine to the posterior abdominal wall.

Digestive tract consist of four layers, called tunics.

Mucosa, submucosa, muscularis, and serosa/adventitia.

Digestive tract

Open at the mouth and anus. Consists of the oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, and anus. - Salivary glands empty into the oral cavity, and the liver and pancreas are connected to the small intestine.

Retroperitoneal

Other abdominal organs that lie against the abdominal wall, have no mesenteries. - Includes the duodenum, pancreas, ascending colon, descending colon, rectum, kidneys, adrenal glands, and urinary bladder.

4. Serosa or adventitia

Outermost layer Consists of peritoneum, which is a smooth epithelial layer, and its underlying connective tissue. - Region not covered by periotoneum are covered by a connective tissue layer called the adventitia.