Non-Ruminants+-+Mice

=Non-Ruminants - Mice=

Pre-Small Intestine (Group 3 - Candace H)
Mice use their front paws for prehension, where they preform mechanical digestiuon by masticating the feed and salivary amylase breaks down starches. The salivary amylase is contined in the saliva secreted by the salivary glands which also contains water, sodium bicarbonate as a buffer, and mucin as a lubricant and which also helps form the feed into a bolus for degluition. During degluition peristalsis pushes the bolus down the esophagous into the stomach and the esophageal sphincter closes behind it. While in the stomach it is churned with HCl and pepsin to digest it further. Thenthe pyloric sphincter opens and it ispushed into the small intestine. What about protein digestion? Pepsin.

Small Intestine (Group 3 - Teal K)
The small intestine in mice is divided into three segments: duodenum, jejunum, and ileum. The lumen surface of the small intestine is covered by millions of small projections called villi. Furthermore, abosorbtion and metabolism takes place in the gut lumen before the compounds enter the portal vein. More info, please. Zymogens, enzymes, micelles, etc. See the dog's SI for good example.

Large Intestine (Group 3 - Sarah L)
The large intestine in the mouse (and all other mammals) is made up of the cecum, colon, and rectum. These three portions share the same wall structure, which consists of the innermost layer, which is known as the mucosa, which is surrounded by the submucosa. The submucosa is surrounded by the muscularis interna and externa layers. The muscularis interna and externa layers are surrounded by the outermost layer, which is known as the serosa. The mucosa of the large intestine is comprised of simple columnar epithelium and lamina propria. The lamina propria is a constituent of the moist linings known as mucous membranes or mucosa, which line various tubes in the body, as in this case, the large intestine.

In mice, the first part of the large intestine, known as the cecum, has a large lumen (central opening in the large intestine), and does not have an appendix (like us humans do) the hypothesis is that humans' appendix was a cecum at some point a long time ago. so the mouse has a cecum therefore would not have an appendix. The mucosa in the mouse’s cecum is very thin and forms transverse folds. The cecum is where microbes such as fungi, bacteria, and protozoa digest fibrous carbohydrates. When the fiber is broken down, Volatile Fatty Acids are produced by these microbes and are absorbed through the cecal wall and used for energy. These microbes also synthesize B-vitamins and Vitamin K.

The next part of the mouse’s large intestine, the colon, is made up of cuboidal cells and Goblet cells. Goblet cells in the colon secrete mucous, which is very important because it helps protect the colon and acts as a transportation aid when all the undigested, fibrous material that didn’t get absorbed by the small intestine travels through the large intestine. Also, the colon contains no villi, so not much of anything is being absorbed. The colon has all the same funtions of the cecum, so Volatile Fatty Acids are produced, B-vitamins are being synthesized, and microbial digestion is occurring. Water reabsorption and fecal concentration also take place in the colon.

The last part of the mouse’s large intestine is known as the rectum. Here, feces form from undigested material. Some of this material includes, sloughed bacteria, dead cells, fluid, and unabsorbed feedstuffs. The mouse’s rectum partly determines the shape and size of the mouse’s feces. In the mouse, the rectum is particularly short. The mucosa and submucosa of the rectum form longitudinal folds. The rectum has a well-developed muscularis mucosae, a thick muscularis interna, and a thin muscularis interna.

Post Large Intestine (Group 3 - Ashley G)
After the large intestine and the rectum comes the anus. The rectum has formed undigested material into feces. The anus controls the exit of feces. The rectum is part of the LI so this part would only be the anus.