Digestive System. Types of Digestion. Teeth/Saliva. Digestive SystemOver -

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1 Digestive SystemOver - Digestive System Disassemble the food you eat into smaller parts that can be used to make energy (ATP) by your body and provide nutrients. Types of Digestion Mechanical digestion physically breaks up and crushes food. This occurs in both the mouth (teeth) and stomach. Chemical digestion breaks down food into molecules using enzyme (special proteins) and acids. Chemical digestion begins in the mouth and continues into the stomach and small intestine. The pathway for food and drink as it enters the digestive system on it s path through the body. Remember food never really goes into the body but rather travels through it. Teeth/Saliva Teeth are the 1st step of digestion. They help break down the food to make it smaller and easier to swallow. Teeth are attached to strong muscles and jaw bones to help you break and grind your food. As you chew, your saliva gets mixed in with the food and makes it softer. Saliva contains enzymes that break down carbohydrates

2 The epiglottis A flap of cartilage that closes over the opening to the respiratory tract as you swallow, keeping food out After food passes, epiglottis opens again If you talk or laugh as you swallow, food may enter the upper portion of the respiratory tract Esophagus After you swallow, your food travels down the esophagus, a long straight tube. The esophagus squeezes the food with rhythmic muscles and pushes the food along to the stomach. No absorption takes place in the esophagus. Food and drink form a bolus that moves by peristalsis down towards the stomach. Your response is to choke & cough, forcing food out of the respiratory tract Peristalsis A series of involuntary smooth muscle contraction along the walls of the digestive tract Stomach The lining of the stomach secretes mucus that forms a protective layer between it and the acidic environment of the stomach Food remains in stomach for about 2-4 hrs When food leaves it is the consistency of tomato soup (YUMMY!).

3 Stomach The stomach continues the digestion by squeezing the food and adding acids that digest food. The stomach churns the food until it turns into a milky liquid called chyme. Then, the food passes to the small intestine. Small Intestines A muscular tube about 6 m long Called small because of how narrow it is (only 2.5 cm in diameter) - Digestion is COMPLETED here - First 25 cm of the small intestine called the duodenum The small intestine then absorbs the nutrients and minerals from the food. Sending nutrients into the capillaries that surrounds the small intestines. Small Intestines Liquid food stays in the intestine for 3-5 hrs. as it is moved through As food moves it passes over thousands of tiny fingerlike structures called villus = a single projection on the lining of small intestine that function in the absorption of food Now that food is in the form of small molecules, it can be absorbed directly into the cells of the villi (plural for villus) Food then diffuses into blood vessels of the villus & enter the bloodstream Pancreas A soft, flattened gland that secretes both digestive enzymes & hormones into the small intestine. The mixture of enzymes it releases break down carbohydrates, proteins, & fats

4 Liver Liver play a role in both the circulatory system as well as the digestive system. The liver processes the nutrients you eat so they can be used by the rest of your body. It also stores nutrients for later use. Gall Bladder Stores bile made by the liver and secretes this bile into the small intestine. Bile breaks up fats into small droplets (much like soap does) so that they can be broken down and absorbed Large Intestines - All indigestible material from a meal then moves into the large intestine = a muscular tube that is also called the colon - Large intestine is only about 1.5 m long, but it is much wider that the small intestine ( about 6.5cm in diameter) Large Intestines As indigestible mixture passes through the large intestine, water and salts are absorbed by the intestinal walls, leaving behind a more solid material This way water is NOT wasted Bacteria in the large intestine make some B vitamins and Vitamin K, which are absorbed as needed by the body These bacteria also stop harmful bacteria from colonizing, reducing the risk of intestinal infections

5 End of Digestive End EnESystem Rectum: END of the digestive system where feces is stored until eliminated out through anus. No picture need :) Proteins in food are broken down into smaller pieces then used to make more proteins with a specific function. Fat from food is broken down into fatty acids so it can travel in the blood and be captured by hungry cells. Then, the fatty acids that are not needed right then are packaged away in bundles that are kept in fat cells. Your body breaks down the carbs into simple sugars which are then absorbed into the bloodstream. Next, the sugar level rises and your pancreas release insulin.

6 Water to dissolve substances in blood, tissue fluids and biochemical reactions Fiber is plant material that the body cannot digest that helps keep your food moving through the digestive system and out.

7 Which systems does the digestive system work with? Circulatory Muscular Lymphatic Ci Circulatory System working with the Digestive System