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Questions and Answers
Match the following terms with their correct function:
Peristalsis = Controls food movement into the duodenum Villi and microvilli = Increase intestinal surface area for absorption Pylorus = Controls food propulsion and stomach emptying Peyer's patches = Found in the mucosa of the ileum
Match the following organs with their secretions:
Liver = Bile secretion Pancreas = Pancreatic juice secretion Gallbladder = Bile storage Duodenum = Receives secretions through the hepatopancreatic sphincter
Match the following structures with their locations:
Circular folds = Found in the small intestine Serosa = Covers most of the digestive organs Adventitia = Covers the duodenum Smooth muscle sheet with pacemaker cells = Sets the rate of peristalsis in the stomach
Match the following substances with their properties:
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Match the following terms with their respective functions in digestion:
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Study Notes
Overview of the Digestive System
- The digestive system consists of organs of the alimentary canal and accessory digestive system organs.
- The alimentary canal includes: mouth, pharynx, esophagus, stomach, small and large intestines.
- Accessory digestive system organs include: teeth, tongue, salivary glands, liver, gallbladder, and pancreas.
Digestive Processes
- The six digestive processes are: ingestion, propulsion, mechanical breakdown, digestion, absorption, and defecation.
- Ingestion is the intake of food.
- Propulsion is the movement of food through the tract.
- Mechanical breakdown is the physical mixing or breaking of food into smaller fragments.
- Digestion is the breakdown of food by enzymatic action.
- Absorption is the transport of products of digestion through the intestinal mucosa into the blood.
- Defecation is the elimination of undigested residues from the body.
The Stomach
- The stomach is J-shaped and lies in the upper left quadrant of the abdomen.
- The stomach has four major regions: cardia, fundus, body, and pyloric part.
- The stomach mucosa is simple columnar epithelium with gastric pits and glands.
- Gastric glands contain secretory cells: chief cells, parietal cells, mucous neck cells, and enteroendocrine cells.
- The stomach muscularis has a third layer of smooth muscle that allows it to churn and mix food.
Gastric Secretion and Regulation
- Parietal cells secrete hydrochloric acid and intrinsic factor.
- Chief cells produce pepsinogen.
- Mucous neck cells produce mucus.
- Enteroendocrine cells secrete hormones.
- The mucosal barrier protects the stomach from self-digestion and HCl.
- Protein digestion is initiated in the stomach by activated pepsin and requires acidic conditions.
Control of Gastric Secretion
- Gastric secretion is controlled by both nervous and hormonal factors.
- The three phases of gastric secretion are cephalic, gastric, and intestinal.
- Most food-related stimuli stimulate gastric secretion.
- Vagovagal reflexes and sympathetic activity also regulate gastric secretion.
The Small Intestine
- The small intestine is the major digestive and absorptive organ.
- It has three subdivisions: duodenum, jejunum, and ileum.
- The small intestine extends from the pyloric sphincter to the ileocecal valve.
- The bile duct and pancreatic duct join to form the hepatopancreatic ampulla and empty into the duodenum.
- Circular folds, villi, and microvilli increase the intestinal surface area for digestion and absorption.
- The duodenal submucosa contains elaborate mucus-secreting duodenal glands.
- The mucosa of the ileum contains Peyer's patches (lymphoid follicles).
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Description
Learn about the organs of the digestive system including the alimentary canal and accessory organs. Content adapted from 'Human Anatomy and Physiology' textbook by Eliane N. Marieb. Presented by Dr. Naim Kittana from An-Najah National University.
