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Digestion

Digestion. 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

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Digestion

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  1. Digestion Chapter 6.1

  2. 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

  3. 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. • Once broken apart, their monomer can pass through (like amino acids or glucose molecules)

  4. 6.1.1: Explain why digestion of large food molecules is essential • Large molecules (like proteins, lipids, and starches) are made of smaller subunits (amino acids, glycerol/fatty acids, and glucose) • Our body needs to break down the polymers into monomers (hydrolysis) to be broken down into macromolecules that are useful to us • Ex: egg white – serine (aa) – used for protein synthesis

  5. 6.1.2: 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

  6. 6.1.3: State the source, substrate, products and optimum pH conditions for 1 amylase, 1 protease, & 1 lipase

  7. 6.1.4: Draw and label a diagram of the digestive system • To be done on the board in class

  8. Define peristalsis and describe its role in the digestive tract • Peristalsis: sequential series of smooth muscle contractions to move food down the digestive tract • Pushes and churns the food (bolus) as it makes its way from the mouth to the anus

  9. List the functions of saliva • After chewing and breaking up food (increasing the surface area), saliva has the following functions: • Mucin (glycoprotein): protects the mouth and makes food slippery • Buffers: prevent rotten teeth by neutralizing acid • Antibacterial agents • Salivary Amylase: begins digestion of starch

  10. Describe the function of the esophagus • Esophagus: moves food from pharynx to the stomach • Voluntary swallowing, involuntary peristalsis • Starches continue digestion

  11. 6.1.5: 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

  12. 6.1.5: Outline the function of the stomach, small intestine, and large intestine (continued) • 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

  13. Explain how chyme is moved through the small intestine • Peristalsis churns and pushes the chyme through the portions of the small intestine

  14. 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

  15. 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

  16. 6.1.6: 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

  17. 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

  18. 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

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