Bio6 Flashcards
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Nutrition is the science of how nutrients in food affect health. Macromolecules, needed in large amounts, are proteins, carbs, and lipids. Carbs are broken down into glucose and excess carbs are stored as fat. Lipids are made of a glycerol and fatty acid chain. They store energy for later use and provide insulation and even make up some hormones. Three types of lipids are saturated fats which are unhealthy, unsaturated fats which are healthy, and hydrogenated unsaturated fats called trans fat that is also unhealthy. Proteins are building blocks that are made of amino acids. They also function as enzymes. Micronutrients, needed in small amounts, are vitamins and minerals. Minerals are inorganic and vitamins are organic like the macronutrients. Minerals play a role in cell processes like bone formation or muscle contraction. Mg supports enzyme activity. Vitamins can be water soluble or fat soluble. Water soluble vitamins cant be stored in the body, and fat soluble vitamins are not easily eliminated. They are stored for later use. Water is not a source of energy many substances can dissolve in it and it does things like flushing toxins or lubricate tissues, so the body is 60 percent water.
The digestive system
. The stomach, which can hold 1.5 L of food, is where bolus becomes chyme. Its churns food and its glands secrete enzymes to break food down. Pepsin digests proteins and rennin which is only in kids absorbs nutrients from milk. Smoking relaxes the cardiac sphincter and stimulates acid production contributing to heart burn. The small intestine is 6 meters long and has villi and microvilli that are filled with capillaries where blood absorbs the nutrients. The chemical digestion is done by enzymes that are added in the duodenum. They break molecules down so they can be absorbed in the ileum and jejunum.The acidity of chyme triggers the duodenum to release secretin, which signals the pancreas to release bicarbonate ions that neutralize the HCL in the duodenum. The pancreas also releases lipase which breaks down fats, amylase which breaks down disaccharides, and trypsin which breaks down protein. Sucrase, maltase and lactase digest sugars. The stomach and intestines have four layers: the mucosa, submucosa, muscularis externa and serosa. The liver is about 3 pounds and detoxifies blood of stuff like alcohol. By the time food gets to the large intestine most of the nutrients have been absorbed. The large intestine has a smooth mucus lining to help food move through it. It absorbs water and salt. It also contains about 500 species of bacteria that make important substances like vitamin B. Fibers is indigestible, but important beca they help us feel full and aid in egestion. Nerves in the gut wall initiate the defecation reflex. Stool is 75% water. Our bodies can make vitamin A, D, and K.
