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Chapter 6.1 The hierarchy of the human body The body is composed of cells Tissues consist of groups of cells with a common structure and function Organs consist of tissues with common structure and function Organ systems consist of organs with common structure and function Physiology: the study of how organ systems in the body interact with each other DIGESTION Digestion: taking large molecules and breaking them apart so that the body can use them It is essential because these large molecules cannot get through the lipid bilayer of the cell membrane. Once broken apart, their monomer (e.g. amino acids or glucose molecules) can pass through Explain why digestion of large food molecules is essential Large molecules (like proteins, lipids, and starches) are insoluble in water and can not be absorbed into the blood stream Large molecules (polymers) need to be broken down into smaller molecules (monomers) such as glucose, amino acids, fatty acids & glycerol which are soluble in water and can easily be absorbed into blood stream Once absorbed, monomers are used to build essential molecules in the body. Explain the need for enzymes in digestion Enzymes: specialized proteins with an active site that creates an environment for specific chemical reactions to occur Enzymes not only allow reactions to occur, they lower the activation energy required for the desired reaction so it can happen more quickly Digestive enzymes help to catalyze hydrolysis reactions Each enzyme is specific for a specific food type State the source, substrate, products and optimum pH conditions for amylase, protease, & lipase Enzyme Source Substrate Products salivary amylase Salivary glands starch maltose 7-8 pepsin stomach proteins polypeptides 2-3 Pancreatic lipases pancreases triglyceride lipid Fatty acids & glycerol 7.2 Optimum pH Draw and label a diagram of the digestive system Outline the function of the stomach, small intestine, and large intestine Stomach: functions in the following: Storage of food and water Gastric juice: acidic fluid (HCl) breaks up cells and kills bacteria pepsin for protein digestion Mucus to protect lining of stomach from HCl Mix-churn food becoming acid chyme Outline the function of the stomach, small intestine, and large intestine Small Intestine: where most absorption and food breakdown occurs Duodenum: upper portion Secretions from accessory organs combine to assist in digestion: Bile from liver & gallbladder Trypsin, lipase, amylase & bicarbonate from pancreas Jejunum & Ileum: absorption Explain how chyme is moved through the small intestine Peristalsis churns and pushes the chyme through the portions of the small intestine Explain the function of bile, describe where it is produced and stored, and describe its composition Bile: produced in the liver, stored in the gall bladder Contains bile salts which make fats soluble and digestible Contains iron from hemoglobin of RBCs Bile molecules insert themselves between lipid molecules preventing lipids from forming large globules 6.1.5: Outline the function of the stomach, small intestine, and large intestine (continued) Large Intestine: reabsorbs water Water is released into the digestive tract to help with food breakdown Water must be reabsorbed by the body to prevent dehydration The solids that remain (feces) are eliminated Distinguish between absorption and assimilation Absorption: active or passive uptake of nutrients The cell taking in amino acids from the small intestine Assimilation: Conversion of nutrients into useful substances in the body The cell using those amino acids to build proteins 6.1.7: Explain how the structure of the villus is related to its role in absorption and transport of the products of digestion Villus: large finger-like fold in the intestinal wall 6.1.7: Explain how the structure of the villus is related to its role in absorption and transport of the products of digestion (continue) Each Villus has microscopic folds called microvilli These folds upon fold increase surface area The small intestine’s purpose is to breakdown and absorb nutrients – the more area possible to do this, the more efficient the process