Digestion Lecture Study Guide Based on information found in the lecture folder or other sources, answer the following questions. 1. What is digestion? Digestion is the mechanical and chemical breakdown of food into usable molecules 2. List some other names of the digestive tract. Alimentary Canal (GI Tract) 3. Explain where and how the mechanical breakdown of food occurs. Teeth begin digestion mechanically, Chewing (“mastication”) breaks apart food, 2 sets of teeth, and the teeth are, Incisors for cutting, Canines “fangs” for tearing, and Premolars and molars for grinding 4. How does food move through the digestive tract?
Movement through the tube which is by wavelike motion called peristalsis 5. What is released from the gall bladder when food is in the duodenum? Cholecystokinin 6. The organs of the digestive tract form a continuous tube from mouth to anus. List the organs of the tract including specific regions of the small and large intestine, from proximal to distal in the blanks… Mouth -> pharynx________ -> _______esophagus_________ -> __________Stomach_______ -> small intestine -> __________ Duodenum______ -> ____ Jejunum_____________ -> ____________ Ilium _______ -> large intestine: cecum, ppendix, -> ________ ascending colon_____________ -> _________ transverse colon____________ -> ___ descending colon_______________ -> _____ Sigmoidal colon_______________ -> ___ involuntary sphincter__________________ -> ____ voluntary sphincter_______________ -> anus 7. Fill in the chart. |Organ |Function |Secretes |Helps to digest what food | | | | |type (carb, prot,fat)? |Mouth |Chewing breaks the food into|Saliva |starches to sugar | | |pieces that are more easily | | | | |digested, while saliva mixes| | | | |with food to begin the | | | | |process of breaking it down | | | | |into a form your body can | | | | |absorb and use. | | |Esophagus |the esophagus receives food |NA | | | |from your mouth when you | | | | |swallow. By means of a | | | | |series of muscular | | | | |contractions called | | | | |peristalsis, the esophagus | | | | |delivers food to your | | | | |stomach. | | |Stomach |The stomach is a hollow |secretes gastric juices |protein digestion | | |organ, or “container,” that |(pepsin, hydrochloric acid) | | | |holds food while it is being|which digest proteins and | | | |mixed with enzymes that |creates a paste of food | | | |continue the process of |called chyme | | | |breaking down food into a | | | | |usable form. Cells in the | | | | |lining of the stomach | | | | |secrete strong acid and | | | | |powerful enzymes that are | | | | |responsible for the | | | | |breakdown process.
When the | | | | |contents of the stomach are | | | | |sufficiently processed, they| | | | |are released into the small | | | | |intestine. | | | |Pancreas |first segment of the small |secretes pancreatic juice |protein, fats, and | | |intestine.
The pancreas also|which helps digest |carbohydrates | | |makes insulin, secreting it | | | | |directly into the | | | | |bloodstream. Insulin is the | | | | |chief hormone for | | | | |metabolizing sugar. | | | |liver |In addition, the liver is |conversion of excess glucose|Glucose | | |the body’s chemical |into glycogen for storage | | | |”factory. It takes the raw | | | | |materials absorbed by the | | | | |intestine and makes all the | | | | |various chemicals the body | | | | |needs to function. The liver| | | | |also detoxifies potentially | | | | |harmful chemicals.
It breaks| | | | |down and secretes many | | | | |drugs. | | | |Gallbladder |The gallbladder stores and |NA |fats | | |concentrates bile, and then | | | | |releases it into the | | | | |duodenum to help absorb and | | | | |digest fats. | | |Small intestine |the small intestine is a |Receives secretions from |starches, proteins and fats | | |22-foot long muscular tube |pancreas and liver, | | | |that breaks down food using |completes digestion of | | | |enzymes released by the |nutrients in chyme | | | |pancreas and bile from the | | | | |liver. | | |Large intestine |The large intestine is a |NA |reabsorb water, and absorb | | |highly specialized organ | |certain minerals and | | |that is responsible for | |vitamins | | |processing waste so that | | | | |emptying the bowels is easy | | | | |and convenient. | | | | | | | | |Anus |It lets you know whether the| |Bile | | |contents are liquid, gas, or| | | | |solid.
The anus is | | | | |surrounded by sphincter | | | | |muscles that are important | | | | |in allowing control of | | | | |stool. The pelvic floor | | | | |muscle creates an angle | | | | |between the rectum and the | | | | |anus that stops stool from | | | | |coming out when it is not | | | | |supposed to.
The internal | | | | |sphincter is always tight, | | | | |except when stool enters the| | | | |rectum. It keeps us | | | | |continent when we are asleep| | | | |or otherwise unaware of the | | | | |presence of stool. | | | 8. What are the 3 major classes of food?
Which is the first and last to be broken down during digestion? Proteins, Carbohydrates, and Lipids (fats). The first is Carbohydrates, and the last broken down are starches, proteins and fats. 9. What are the major vitamins we need and why? Vietnam A for healthy eyes, skin, bones and hormone synthesis Vietnam C for collagen, detoxification Foliate needed for DNA and RNA metabolism Niacin, Biotin, Thiamin needed for energy metabolism 10. List the major minerals we need and what purpose they serve in our bodies. The body needs 7 – potassium, sulfur, sodium, chloride and magnesium in addition to trace amounts; the purposes they serve are: Phosphorus needed for bone and tooth formation
Magnesium needed for bone, tooth, and enzyme formation Sulfur needed for cartilage, tendon, and proteins Sodium needed for nerve impulse transmission Potassium – nerve function Chloride – gastric juices and electrolyte balance 11. Name the 3 pairs of salivary glands. The parotid The submandibular salivary gland The sublingual salivary glands 12. What tissue type and muscle type do you find in the esophagus? How does affect function? The lining of the esophagus is stratified squamous non-keratinized epithelia. the esophagus is continuous with the laryngeal part of the pharynx at the level of the C6 vertebra 13. Where does the pancreas empty digestive enzymes? Small Intestine 4. Where does the gall bladder empty digestive enzymes? All that is missing is a small storage sac for bile, and goes to bladder. 15. In which part of the digestive system does food spend the most time? small intestine 16. What are the muscles like in the stomach? Smooth muscles — sometimes also called involuntary muscles — are usually in sheets, or layers, with one layer of muscle behind the other. 17. What are goblet cells, Peyer’s patches, and villi? Where are they found and why are they important? Goblet cells. These mucus-secreting cells are the second most abundant epithelial cell. They are found interspersed among the other cell types.
Their mucous is a very large glycoprotein that accumulates at the apical end of the cell, rendering it wide. Peyer’s patches are areas of specialized tissue in the lower area of the small intestine that work to distinguish friend from foe as food passes through the gastrointestinal tract. The Peyer’s patches pass the word to the rest of the intestinal tract, facilitating either digestion or uptake of nutrients or an immune system attack on an invader. Villi is a microscopic finger-like projections that line the inner wall of the small intestine. After food passes from the stomach into the small intestine, nutrients in the food are absorbed into the body through the villi 18. Where is most digested food absorbed?
Most of the digested food is absorbed in the small intestine. 19. What is the main function of the large intestine? The main function of the large intestine is to transport waste out of the body and to absorb water from the waste before it leaves. 20. What causes heartburn? The basic cause of heartburn is a lower esophageal sphincter, or LES, that doesn’t tighten as it should. Two excesses often contribute to this problem: too much food in the stomach or too much pressure on the stomach (frequently from obesity or pregnancy). Certain foods commonly relax the LES, including tomatoes, citrus fruits, garlic, onions, chocolate, coffee, alcohol, caffeinated products, and peppermint.
Dishes high in fats and oils (animal or vegetable) often lead to heartburn, as do certain medications. Stress and lack of sleep can increase acid production and can cause heartburn. And smoking, which relaxes the LES and stimulates stomach acid, is a major contributor. 21. How long is the human digestive system? he digestive tract is approximately 20 feet (6. 5 meters) in a normal human adult male. 22. Describe the structure and function of villi. Villi are numerous finger-like projections on the walls of small intestine. It helps in the absorption of dissolved food substances from intestine to other parts of the body. Villi increase surface area so as to speed up rate of diffusion 23.
What is the relationship of size between large and small intestine? The small intestine is longer than the large intestine, although it has a smaller width. The small intestine is between the stomach and the large intestine. The large intestine is the last part of the digestive system 24. Name the 3 pair of salivary glands and explain the function of saliva. •Parotid glands produce serous fluid containing enzymes, electrolytes, and limited mucin •Submandibular and sublingual gland produces a more viscous fluid than parotid glands •Saliva functions include: Protection (esp. antibacterial lysozyme and IgA antibodies) Taste (dissolved food chemicals) Lubrication (mucus)
Digestion (esp. starch via amylase) 25. What does amylase digest? It breaks starches down to sugars. 26. Explain where and how the mechanical breakdown of food takes place. Mechanical digestion is the cutting, chewing, grinding, crushing food into smaller pieces to increase the surface area for the chemical digestion step. In the mouth, food is mechanically digested by the teeth chewing and grinding. Food is then chemically digested using enzymes in the Sylvia, such as amylase, which breaks down starch. 27. Why is the stomach acid and how does the stomach protect itself from being digested? Gastric acid is a digestive fluid, formed in the stomach.
It has a pH of 1. 5 to 3. 5 and is composed of hydrochloric acid (HCl) (around 0. 5%, or 5000 parts per million), and large quantities of potassium chloride (KCl) and sodium chloride (NaCl). It protects itself from being digested by a mucus lining. 28. What are the end products of protein, fat, and carbohydrate digestion? Proteins –> amino acids Carbohydrates –> monosaccharaides (mainly glucose) and dextrin’s Fat –> fatty acids and glycerol 29. Solid wastes are discharged through the ____. Anus 30. How many calories are produced when 1 gram or carbohydrate is oxidized? What about 1 gram of protein and 1 of fat? 4 and 9 31. Define: a. mulsify, disperse a liquid into another liquid with which it is immiscible, making a colloidal suspension. Soaps and detergents emulsify by surrounding small globules of fat, preventing them from settling out. Bile acts as an emulsifying agent in the digestive tract by dispersing ingested fats into small globules. b. peristalsis, the wormlike movement by which the alimentary canal or other tubular organs having both longitudinal and circular muscle fibers propel their contents, consisting of a wave of contraction passing along the tube for variable distances. c. Constipation, Constipation is an acute or chronic condition in which bowel movements occur less often than usual or consist of hard, dry stools that are painful or difficult to pass.
Bowel habits vary, but an adult who has not had a bowel movement in three days or a child who has not had a bowel movement in four days is considered constipated. d. Diarrhea, Excessive and frequent evacuation of watery feces, usually indicating gastrointestinal distress or disorder. e. Metabolism, The chemical processes occurring within a living cell or organism that are necessary for the maintenance of life. In metabolism some substances are broken down to yield energy for vital processes while other substances, necessary for life, are synthesized. f. anabolism, a metabolic process in which complex molecules are synthesized from simpler ones with the storage of energy g. catabolism, The metabolic breakdown of complex molecules into simpler ones, often resulting in a release of energy. h. luconeogenesis, The formation of glucose, especially by the liver, from non-carbohydrate sources, such as amino acids and the glycerol portion of fats. i. Glycogenolysis The biochemical breakdown of glycogen to glucose.
j. Glycogenesis The formation or synthesis of glycogen. k. BMR basal metabolic rate l. Pharynx The section of the alimentary canal that extends from the mouth and nasal cavities to the larynx, where it becomes continuous with the esophagus. m. Esophagus The muscular membranous tube for the passage of food from the pharynx to the stomach; the gullet. n. Pyloric sphincter A ring of smooth muscle fibers around the opening of the stomach into the duodenum. o. arietal cells One of the large peripheral cells of the mucous membrane of the stomach that secrete hydrochloric acid. p. Dentin The main, calcareous part of a tooth, beneath the enamel and surrounding the pulp chamber and root canals. q. propulsion r. buccal phase the tongue pushes bolus of food into oropharynx. s. rennin An enzyme that catalyzes the coagulation of milk, found in the gastric juice of the fourth stomach of young ruminants and used in making cheeses and junkets. t. Ulcer lesion of the skin or a mucous membrane such as the one lining the stomach or duodenum that is accompanied by formation of pus and necrosis of surrounding tissue, usually resulting from inflammation or ischemia.