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The Digestive System Part 1 Anatomy of… Chapter 14 Photo Credit: science.nationalgeographic.com The Big Picture • Our digestive system o Takes in food o Breaks it down with mechanical and physical processes into nutrients o It then absorbs these nutrients into the blood stream o Then rids the body of the unused remains The Alimentary Canal • The alimentary canal is the “tube” that our food and ultimately our food waste travel through. • These notes, part 1, look at the organs that form the canal. • Part 2 looks at the organs that help in the process of digestion; the accessory organs. In the above figure, all the labeled parts but the liver form the alimentary canal Organs of the Alimentary Canal • When you put something in your mouth, and if it later pops out your anus, it traveled through your body but it was never inside your body • Here’s the list of organs that “something” would come in contact with o Mouth o Pharynx Putting food in your o Esophagus body is like putting your finger through a o Stomach donut; it passes o Small intestine through the donut but never enters the o Large intestine donut! o Anus Mouth • The mouth is also called the oral cavity • The players here are the lips, cheeks, hard palate (anterior roof of mouth), soft palate (posterior roof of mouth), uvula (dangles from the soft palate), tongue, and teeth Uvula • The uvula seems to function in aiding speech, swallowing, prevent food from entering nasal cavity, and in the “gag” reflex Pharynx • As food is leaving the mouth it passes into the pharynx • The pharynx is the common area that both food and air pass through Esophagus • A 10” long tube from mouth to stomach • Below is a an endoscope view looking into this tube Stomach • A sac with two valves at both ends. The cardioesophageal sphincter at the top and the pyloric spincter valve at the bottom • It can hold up to 4 L or a gallon of food and is used in both digestion and temporary storage Small Intestine • It’s big; the major player in digestion, and the longest part at up to 13’ long in a live person. • Has three major parts o Duodenum o Jejunum o ileum The small intestine is lined with intestinal villi increase surface area to absorb nutrients, connect to vessels Large Intestine • Short (5’) but bigger diameter than the small intestines • It absorbs water and dries out the waste • It’s divided into parts: o o o o Ascending colon Transverse colon Descending colon Sigmoid colon • The sigmoid colon leads to your anus and the end of the tube… How to Make Fake Poop... Photo Credit: http://www.biologycorner.com