Human Digestive System: Organs and Functions
Classified in Biology
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Digestive Process
| Organ | Movement | Digestive Juices Used | Food Particles Broken Down |
|---|---|---|---|
| Mouth | Chewing | Saliva | Starches |
| Esophagus | Swallowing | None | None |
| Stomach | Upper muscle in the stomach relaxes to let food enter, and the lower muscle mixes food with digestive juice | Stomach acid | Protein |
| Small Intestine | Peristalsis | Small intestine digestive juice | Starches, protein, and carbohydrates |
| Large Intestine | Peristalsis | Pancreatic juice | Starches, fats, and protein |
| Rectum | Peristalsis | Bile acids | Fats |
Key Components of the Digestive System
- Epiglottis: A flap of cartilage at the root of the tongue, which is depressed during swallowing to cover the opening of the windpipe.
- Esophagus: The tube that extends from the throat to the stomach.
- Lower Esophageal Sphincter: A bundle of muscles at the low end of the esophagus, where it meets the stomach. When the LES is closed, it prevents acid and stomach contents from traveling backward from the stomach.
- Stomach: The internal organ in which the major part of the digestion of food occurs.
- Hydrochloric Acid: Breaks down proteins in your stomach to prepare them for digestion and kills bacteria that enter your stomach.
- Gastrin: A peptide hormone that stimulates the secretion of gastric acid (HCl) by the parietal cells of the stomach and aids in gastric motility.
- Chyme: The liquid substance found in the stomach before passing through the pyloric valve and entering the duodenum.
- Pepsin: An enzyme that breaks down proteins into smaller peptides.
- Pyloric Part: Connects the stomach to the duodenum. The pylorus is considered as having two parts:
- Pyloric Antrum (opening to the body of the stomach)
- Pyloric Canal (opening to the duodenum).
- The pyloric canal ends as the pyloric orifice, which marks the junction between the stomach and the duodenum. The orifice is surrounded by a sphincter, a band of muscle, called the pyloric sphincter.
- Small Intestine: The part of the intestine that runs between the stomach and the large intestine; the duodenum, jejunum, and ileum collectively.
- Important villous membranes include the placenta and the mucous-membrane coating of the small intestine.
- The villi of the small intestine project into the intestinal cavity, greatly increasing the surface area for food absorption and adding digestive secretions.
- Microvilli: Microscopic cellular membrane protrusions that increase the surface area of cells and minimize any increase in volume, and are involved in a wide variety of functions, including absorption, secretion, cellular adhesion, and mechanotransduction.