DAE - Module Overview
Digestive System - Absorption & Elimination (DAE)
Introduction
The digestive system is responsible for the breakdown of food. Our bodies require nutrients to maintain the functions of our organ systems. The highlights of digestion tend to be eating (especially something enjoyable like ice cream) and pooping (necessary, but not as pleasurable). But what happens in between the teeth and the tail?
Digestion is dependent upon the specialized organs that hold, break down, and move food throughout the system, as well as a number of accessory organs that support food breakdown and nutrient extraction. This unit will explore the structure and function of the digestive organs.
Essential Questions
- What organs are part of the digestive system?
- What are the functions of the organs of the digestive system?
- How is food moved and mixed through the digestive system?
- Which enzymes do the digestive organs secrete?
- How are digestive secretions regulated?
- What changes occur in the digestive system as the body ages?
Key Terms
- Absorption - nutrients from food that has been broken down enters into the bloodstream
- Alimentary canal - the long tube in the body through which food passes after it is eaten
- Anus - the opening between a person's buttocks through which solid waste passes from the body
- Appendix - a narrow, blind tube usually about three or four inches (7.6 to 10.2 centimeters) long that extends from the cecum in the lower right-hand part of the abdomen
- Bile - a yellowish-green liquid produced in the liver that is essential in the digestion of fats
- Chemical digestion - uses digestive secretions such as enzymes and acids to break down complex food molecules into their chemical building blocks
- Chyme - partially digested food in the stomach that has the appearance of heavy cream
- Colon - the part of the large intestine that extends from the cecum to the rectum
- Defecation - final step in digestion where undigested materials are removed from the body as feces
- Dentes (teeth) - any of the hard bony appendages that are borne on the jaws and serve especially for the prehension and mastication of food
- Digestion - the process by which food is changed to a simpler form after it is eaten
- Digestive system - the bodily system concerned with the ingestion, digestion, and absorption of food
- Duodenum - the first, shortest, and widest part of the small intestine that in humans is about 10 inches (25 centimeters) long
- Esophagus - a muscular tube that in adult humans is about nine inches (23 centimeters) long and passes from the pharynx down the neck between the trachea and the spinal column and joins the cardiac end of the stomach
- Feces - solid waste found in the large intestine
- Gallbladder - a membranous muscular sac in which bile from the liver is stored
- Gingivae (gums) - soft tissue that surrounds the teeth
- Hard palate - the bony anterior part of the palate forming the roof of the mouth
- Ileum - the last division of the small intestine that constitutes the part between the jejunum and large intestine
- Jejunum - the section of the small intestine that comprises the first two fifths beyond the duodenum
- Large intestine - the more terminal division of the vertebrate intestine that is wider and shorter than the small intestine
- Liver - the largest gland in the body located in the right upper quadrant of the abdomen
- Mastication - chewing
- Mechanical digestion - a physical process that makes food smaller to increase its surface area and make it easier to move; does not change the chemical makeup
- Oral cavity (mouth) - the natural opening through which food passes into the animal body and which in vertebrates is typically bounded externally by the lips and internally by the pharynx and encloses the tongue, gums, and teeth
- Pancreas - a large, lobulated gland that in humans lies in front of the upper lumbar vertebrae and behind the stomach and is somewhat hammer-shaped and firmly attached anteriorly to the curve of the duodenum with which it communicates through one or more pancreatic ducts
- Peristalsis - successive waves of involuntary contraction passing along the walls of a hollow muscular structure (as the esophagus or intestine) and forcing the contents onward
- Pharynx - the part of the digestive and respiratory tracts situated between the cavity of the mouth and the esophagus
- Rectum - the terminal part of the intestine from the sigmoid colon to the anus
- Salivary glands - any of various glands that discharge a fluid secretion and especially saliva into the mouth cavity
- Small intestine - the part of the intestine that lies between the stomach and colon, consists of the duodenum, jejunum, and ileum
- Soft palate - the membranous and muscular fold suspended from the posterior margin of the hard palate and partially separating the mouth cavity from the pharynx
- Stomach - a saclike expansion of the alimentary canal of a vertebrate communicating anteriorly with the esophagus and posteriorly with the duodenum
- Tongue - A muscular organ located in the floor of the mouth containing sensory receptors called taste buds
- Villi - Fingerlike processes lining the walls of the small intestine
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