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=**﻿ Period 2 Digestive System **=


 * 1) **Christian Falconer**
 * 2) **﻿Goldie ****Nwankwo﻿h**
 * 3) ﻿Rachel Young

**The Digestive System**

The Digestive System is a complex series of organs series of organs and glands that processes food. In order to use the food that we consume daily, our body has to break it down into smaller molecules that it is able to process and turn into energy. It also excretes waste.

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 * The Digestive Process is composed of many parts with many roles, this process all begins in the mouth. **
 * The mouth- The mouth is responsible for breaking down food by the process of chewing and the enzymes in our saliva.
 * The esophagus- After the food has been chewed and swallowed, the food enters the esophagus. It is a long tube that runs to the stomach. It uses movements called peristalsis to force food down into the stomach (see image below)


 * The Stomach- Once in the stomach the food is bathed, soaked, and churned in gastric acid. The food is only parted digested at this point.
 * The Small Intestine- Arriving from the stomach, food will then enter the duodenum the 1st part of the small intestine. It will the proceed to the jejunum and ileum. The small intestine digests the food with the help of bile (produced in liver & stored in gall bladder). The small intestine also has digestive enzymes produced by its very own inner wall.
 * The Large Intestine- After passing through the small intestine, food passes into the large intestine. In the large intestine, some of the water and electrolytes ) are removed from the food. Many microbes (bacteria like //Bacteroides//, //Lactobacillus acidophilus//, //Escherichia coli//, and //Klebsiella//) in the large intestine help in the digestion process. The first part of the large intestine is called the cecum (the appendix is connected to the cecum). Food then travels upward in the ascending colon. The food travels across the abdomen in the transverse colon, goes back down the other side of the body in the descending colon, and then through the sigmoid colon.


 * ** Here is a video link that helps to explain the process of digestion. **
 * [|Digestion Video]


 * **Gastrin- Makes the stomach produce an acid for digesting and dissolving foods. It is also needed for normal cell growth in the lining of the stomach, colon, and small intestines.**
 * **Liver- A large organ of about 3 pounds that has 2 sections: the left and right lobe. Its job is to filter the blood coming from the digestive tract before it goes to the rest of the body. Blood is carried to the liver from the hepatic artery and the portal vein. It also produces substances that break down fats and produce urea for urine.**
 * **Gallbladder- A very small pouch under the liver. The liver produces bile and the gallbladder stores and squeezes it into the small intestines.**
 * **Pancreas- About 6 inches long behind the stomach. It makes pancreatic juices and hormones that are enzymes that help digest food in the small intestine. It also produces insulin that controls the amount of sugar in the blood.**
 * **Secretion- Makes the pancreas send out the digestive juice. Helps neutralize acid stomach contents. Also stimulates the liver to produce bile and stomach to produce pepsin.**
 * **Here's a quiz on the digestive system: [|Digestive System Quiz]**



**Explore the Digestive System with these fun interactive assimilations.**
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 * **The Regulation Of The Digestive System** ** The activities of the digestive system are regulated by both hormones and neural reflexes. Four important hormones and their effects upon target cells follow . **

>> >> >> >>>> >>>> >>>> >>>> The second regulatory agent of the digestive system is the **nervous system**. Stimuli that influence digestive activities may originate in the head, the stomach, or the small intestine. Based on these sites, there are three phases of digestive regulation: >>>>>> >>>>>> >>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> **Need a video explanation of regulation?**
 * Secretin is produced by the enteroendocrine cells of the duodenal mucosa. Effects include
 * Stimulation of bicarbonate secretion by the pancreas, which neutralizes the acidity of chyme when released into the duodenum.
 * Stimulation of bile production by the liver.
 * Inhibition of gastric juice secretions and gastric motility, which, in turn, slows digestion in the stomach and retards gastric emptying.
 * <span style="margin: 1em 0px 1em 40px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Cholecystokinin is produced by enteroendocrine cells of the duodenal mucosa. Effects include
 * <span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Stimulation of bile release by the gallbladder.
 * <span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Stimulation of pancreatic juice secretion.
 * <span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Relaxation of the hepatopancreatic ampulla, which allows flow of bile and pancreatic juices into the duodenum.
 * <span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Gastric inhibitory peptide is produced by enteroendocrine cells of the duodenal mucosa and causes the inhibition of gastric juice secretion and gastric motility, which, in turn, slows digestion in the stomach and retards gastric emptying.
 * <span style="margin: 1em 0px 1em 40px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">The cephalic phase comprises those stimuli that originate from the head: sight, smell, taste, or thoughts of food, as well as emotional states. In response, the following reflexes are initiated:
 * <span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Neural response. Stimuli that arouse digestion are relayed to the hypothalamus, which, in turn, initiates nerve impulses in the parasympathetic vagus nerve. These impulses innervate nerve networks of the GI tract, which promote contraction of smooth muscles and secretion of gastric juice. Stimuli that repress digestion innervate sympathetic fibers that suppress muscle contraction and secretion.
 * <span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">General effects. The stomach prepares for the digestion of proteins.
 * <span style="margin: 1em 0px 1em 40px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">The gastric phase describes those stimuli that originate from the stomach. These stimuli include distention of the stomach, low acidity, and the presence of peptides. In response, the following reflexes are initiated:
 * <span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Neural response. Gastric juice secretion and smooth muscle contraction are promoted.
 * <span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Hormonal response. Gastrin production is promoted.
 * <span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">General effects. The stomach and small intestine prepare for the digestion of chyme, and gastric emptying is promoted.
 * <span style="margin: 1em 0px 1em 40px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;"><span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">The intestinal phase describes stimuli originating in the small intestine. These include distention of the duodenum, high acidity, and the presence of chyme . In response, the following reflexes are initiated:
 * <span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Neural response. Gastric secretion and gastric motility are inhibited. Intestinal secretions, smooth muscle contraction, and bile and pancreatic juice production are promoted.
 * <span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">Hormonal response. Production of secretin, CCK, and GIP is promoted.
 * <span style="color: #2d53e1; font-size: 14px; font-weight: normal; line-height: 21px; margin: 1em 0px; outline-width: 0px; padding-bottom: 0px; padding-left: 0px; padding-right: 0px; padding-top: 0px;">General effects. Stomach emptying is retarded to allow adequate time for digestion in the small intestine. Intestinal digestion and motility are promote
 * [[image:http://3.bp.blogspot.com/_T8FWnF4zZp0/SwIP2RS9yiI/AAAAAAAAAAc/jJtlAIpF88Q/s1600/human_digestive_system.jpg align="center"]]
 * [[image:http://3.bp.blogspot.com/_T8FWnF4zZp0/SwIP2RS9yiI/AAAAAAAAAAc/jJtlAIpF88Q/s1600/human_digestive_system.jpg align="center"]]
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