Human Nutrition Assignment 3 PDF

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Summary

This course examines the basic concepts of human nutrition and their application to the needs of human beings throughout the life cycle. Discussion of factors affecting food practices and attitudes is included....

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1. Define the terms digestion and absorption. According to the book, digestion is the body’s ingenious way of breaking down foods into nutrients in preparation for absorption. Absorption happens mostly in the small intestine which traps and absorbs the nutrient molecules from the broken-down foods. The nutrients are absorbed into the small intestinal wall’s cells through cellular simple diffusion, facilitated diffusion, and/or active transport. 2. What is the digestive system? The digestive system is a long process mainly starting with food entering the mouth and ending with it being expelled from the body through the anus as waste. It includes how nutrients from food are taken for the body and the process the leftover waste goes through to leave the body. 3. Describe the path food follows as it travels through the digestive system. Summarize the muscular actions that take place along the way. Taken from the book, when food enters the mouth, the salivary glands are activated and secrete saliva which contains starch-digesting enzymes. The mouth chews and mixes the food and saliva to break it down into smaller pieces to make it easier to pass through the esophagus to the stomach. The pharynx, located at the back of the throat, directs the chewed food in the mouth to the upper esophagus sphincter, opening the passage to the esophagus where it passes the epiglottis, a flap that protects food from entering the trachea and lungs during swallowing. As the food travels from the esophagus to the stomach, it passes by the diaphragm which separates the abdomen from the thoracic cavity and then is granted passage through the lower esophagus sphincter before entering the stomach. The stomach adds acid, enzymes, and fluid which churns, mixes, and grinds food to a liquid mass. The liver manufactures bile salts, detergent-like substances, to help digest fats before the food travels to the pyloric sphincter which grants passage for the food from the stomach to the small intestine. From there, bile from the gallbladder and bile duct meet the liquid food to help aid the energy-yielding nutrient enzymes, from the pancreas and pancreatic duct, to turn them into smaller nutrient particles where they can then be absorbed through the cells of the small intestine’s walls to the blood and lymph. The leftovers travel through the ileocecal valve (another sphincter) to the large intestine, also known as the colon. This reabsorbs water and minerals and passes waste (fiber, bacteria, and unabsorbed nutrients) along with water to the rectum. The rectum simply holds the waste until the anus opens to allow for elimination where it exits the body.

4. Name five organs that secrete digestive juices. How do the juices and enzymes from each of these facilitate digestion? There are five organs that secrete digestive juices. They are salivary glands, gastric glands, pancreas, intestinal glands, and liver/gallbladder. Salivary glands produce saliva, a fluid that eases swallowing and contains starch and carbohydrate-digesting enzymes while also

protecting your mouth, throat, and stomach from substances that might harm them. Gastric glands provide gastric juices (water, enzymes, and hydrochloric acid, which has a pH of 2) which play a critical role of killing the bacteria that enter the body with food. In case you were wondering, the five second rule is NOT a valid rule. Bacteria will begin engulfing the food the instant it touches the floor or whatever surface it falls onto. The pancreas is another organ, paired with the small intestine of course, that secretes digestive juices which possess enzymes that help with the digestion and absorption of the main energy yielding nutrients: proteins, carbohydrates, and fats. The liver and gall bladder both produce bile, a fluid that, from the pancreas helps break down the fats before the bile from the gall bladder helps break down the larger nutrient particles for the small intestines to absorb through their walls. 5. How is blood routed through the digestive system? Which nutrients directly enter the bloodstream, and which are first absorbed into the lymphatic system? Blood is a very important function within the digestive system. After exiting the heart from the right side, more specifically the pulmonary artery, it expels carbon dioxide and adds oxygen in the lungs before returning to the heart through its pulmonary vein. The blood then leaves the left side again, this time though the aorta, to the rest of your body either traveling to the upper half or the lower half. When the blood travels away from the heart it can go to the digestive tract followed by the liver, the part we are focusing on, or the pelvis, kidneys, and legs. Nutrients leaving the digestive system entering directly into the blood are watersoluble nutrients like vitamins B and C and smaller products of fat digestion while ones that are first absorbed into the lymphatic system are larger fats and fat-soluble nutrients like vitamin A, D, E, and K. After the blood has traveled through the digestive tract, it comes back to the right side of the heart. The fat-soluble nutrients that end up in the lymphatic system form a fluid called lymph which enters the bloodstream near the heart. 6. Why are gastrointestinal bacteria important for health and regulation? Why are probiotics important? Gastrointestinal bacteria are important for human health and regulation in many ways. They help us fight off bad bacteria that enter the body potentially aiming to harm us and also digest fibers and more complex proteins. To add, the GI bacteria are capable of producing vitamins such as biotin, folate, pantothenic acid, riboflavin, thiamin, thiamin, vitamin B6, vitamin B12, and vitamin K. Probiotics, scientifically knows as Lactobacillus, have several benefits which are helping to alleviate diarrhea, constipation, inflammatory bowel disease, ulcers, allergies, lactose intolerance, and infant colic as well as enhancing immune function and protecting against colon cancer. They supposedly change the conditions and native bacterial colonies of the GI tract in beneficially healthy ways, as stated above....