Digestive System Overview

Flashcards covering the digestive system, its structure, function, and anatomy.

Alimentary canal

Extends from mouth to anus through the ventral body cavity (approximately 9 m, or 30 ft.).

Accessory organs (Digestive System)

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

Catabolism

Breaking down larger molecules into smaller molecules.

Anabolism

Smaller molecules used as building blocks for larger molecules.

Mechanical digestion

Movements that facilitate catabolic processes, increasing contact of food with digestive chemicals.

Chewing

Mastication

Peristalsis

Movement of muscles within the GI tract that facilitates movement of food

Chemical digestion

Breaking large molecules into smaller ones, mainly through hydrolysis.

Four layers of tissues in GI Tract (deepest to superficial)

Mucosa, Submucosa, Muscularis, Serosa/adventitia

Lumen

The inside of the tube (GI Tract).

Mucosa composition

Epithelial tissue, areolar connective tissue (lamina propria), and smooth muscle (muscularis mucosae).

MALT

Mucosa-associated lymphatic tissue that protects against disease.

Submucosa

Irregular connective tissue that binds the mucosa to the muscularis and contains blood and lymphatic vessels.

Submucosal plexus

A network of neurons in the submucosa.

Muscularis

Inner circular sheet and outer longitudinal sheets of smooth muscle.

Serosa/adventitia

Fibrous connective tissue attached to surrounding tissues; covers intra-abdominal organs as the visceral peritoneum.

Peritoneum

The body’s largest serous membrane, wraps around most abdominopelvic organs.

Visceral peritoneum

The serosa of the alimentary canal and covers other intra-abdominal organs.

Parietal peritoneum

The abdominal wall, connects to visceral peritoneum.

Five major peritoneal folds

Greater omentum, falciform ligament, lesser omentum, mesentery, mesocolon.

Greater omentum

Largest peritoneal fold, connects the stomach to the transverse colon.

Falciform ligament

Attaches the liver to the anterior abdominal wall and diaphragm.

Lesser omentum

Suspends the stomach and duodenum from the inferior edge of the liver.

Mesentery & Mesocolon

Attach intestine to posterior abdominal wall.

Retroperitoneal organs

Covered by visceral peritoneum only on their anterior surfaces.

Organs in the retroperitoneal space

The kidneys and ureters, most of the pancreas, the adrenal glands, the aorta and inferior vena cava.

Three overlapping phases of digestive activities

The cephalic phase, the gastric phase, the intestinal phase.

Cephalic phase

Smell, sight, thought, or initial taste of food, stimulates secretion of saliva and gastric juice.

Gastric phase

Food enters the stomach, promotes secretion of gastric juice and gastric motility.

Intestinal phase

Acidic food enters the small intestine, increases intestinal secretions and decreases gastric secretions and motility.

Oral (buccal) cavity

Formed by the cheeks, hard and soft palates, and the tongue.

Mechanical digestion in the mouth

Mastication (chewing)

Saliva function

Mixes with food to soften it; starts chemical digestion of carbohydrates (salivary amylase) and fats (lingual lipase).

Salivary regulation by ANS

Parasympathetic stimulation promotes; sympathetic stimulation decreases.

Teeth (dentes)

Located in sockets of the mandible and maxillae, anchored by the periodontal ligament.

Dentin

Calcified connective tissue that forms most of the tooth.

Enamel

Harder-than-bone calcified non-living material, covers the crown of the tooth.

Tongue

Moves food in the mouth for chewing and swallowing (deglutition) and provides a sense of taste.

Deglutition

Swallowing food from the mouth through the pharynx to the esophagus

Three stages of deglutition

Voluntary, Pharyngeal, Esophageal

Peristalsis

A progression of coordinated contractions and relaxations of the circular and longitudinal layers of the muscularis

Esophagus function

Propulsion is only function (moving food into the stomach).

Esophagus

Connects laryngopharynx to stomach posterior to the trachea

Esophagus Muscularis

Superior 1/3: skeletal muscle

Lower esophageal sphincter (LES)

Regulates the movement of food from the esophagus into the stomach.