HUN 1201 Study Guide for Exam 2 Name: ________________________________________ Chapter 3: 1. What is the difference between hunger and appetite? - Hunger: - Physiological drive for food - Non specific - can be satisfied by a variety of different foods - Appetite: - Psychological desire to consume specific foods - Aroused by environmental cues 2. What are the roles of each of the following in digestion? a. Hypothalamus - triggers feelings of hunger or fullness - located above the pituitary gland in an area of the brain that regulates involuntary activities - integrates signals from nerve cells, hormones, and the types of foods consumed b. Sphincters - muscles that control the passage of food from one GI tract organ to the next c. Chewing - moistens the food and mechanically breaks it into smaller pieces - exposes more surface area to digestive juices d. Taste and Olfactory Receptors - Taste – detect distinct tastes (bitter, sweet, salty, sour, umami) - Olfactory – detect aromas of foods e. Epiglottis - covers the opening to the trachea during swallowing f. Bicarbonate - neutralize acids - found in saliva & the lining of our stomach 3. What is the order of organs in the digestive tract? - Mouth Pharynx/Esophagus Stomach Small Intestine Large Intestine Rectum 4. Define the following and know where they occur: a. Peristalsis - the rhythmic muscle contraction that move food through the GI tract - occurs throughout the GI tract b. Segmentation - Rhythmic contraction of circular muscles in the intestinal wall - Mixes chime and enhance its contact with digestive enzymes and enterocytes c. Haustration - Mass movement that occurs in the colon to move contents - contract very sluggishly5. What are the components of gastric juice? What role does each play? - Hydrochloric Acid – denatures proteins and activates pepsin - Pepsin – enzyme to digest protein - Gastric Lipase – enzyme that digests fats - Intrinsic Factor – protein to absorb vitamin B12 6. What is the function of bicarbonate secreted in the stomach and pancreas individually? - Bicarbonate neutralizes acid in the stomach - Bicarbonate neutralizes chyme in the pancreas 7. What is a bolus and what is chyme? - Bolus – the mass of food chewed and moistened in the mouth - Chyme – liquid product of mechanical and chemical digestion in the stomach 8. What are the 3 sections of the small intestine? -Duodenum - Jejunum - Ileum 9. What are the major functions of the large intestine? - To store undigested food material - And absorb: - Water - Short-chain fatty acids - Electrolytes 10. Review the digestive enzymes and hormones of the gastrointestinal tract (GIT) and their function. a. Hormones: Gastrin, CCK, Grehlin, Secretin, GIP - Gastrin: - Production Site: Stomach - Target Organ: Stomach - Actions: - stimulates secretion of HCl and pepsinogen - stimulates gastric motility - promotes proliferation of gastric mucosal cells - Secretin: - Production Site: Small Intestine – Duodenum - Target Organs: Pancreas and Stomach - Actions: - Pancreas: stimulates secretion of pancreatic bicarbonate - Stomach: decreases gastric motility - Grehlin: - Production Site: Stomach - Plays a role in: - stimulating eating - promoting the activity and motility of the GI tract - regulating carbohydrate metabolism - CCK: - Production Site: Small Intestine – Duodenum & Jejunum - Target Organs: Pancreas, Gallbladder, & Stomach - Actions:- Pancreas: stimulates secretion of pancreatic digestive enzymes - Gallbladder: stimulates gallbladder contraction, signals to release bile - Stomach: slows gastric emptying - GIP – Gastric Inhibitory Peptide - Production Site: Small Intestine - Target Organs: Stomach and Pancreas - Actions: - Stomach: Inhibits gastric acid secretion and slows gastric emptying - Pancreas: Stimulates insulin release b. Digestive Enyzmes: Know all enzymes secreted in mouth, stomach, and small intestine, and know what those enzymes digest. - Mouth - Salivary Amylase: Digests carbohydrates - (produced in the mouth & site of action in the mouth) - Stomach - Pepsin: Digests proteins - Gastric Lipase: Digests Fats - (all produced in the stomach & site of action in the stomach) - Pancreas - Proteases: Digests proteins - Elastase: Digests fiborous proteins - Pancreatic Lipase: Digests Fats - Cholesterol Esterase: Digests cholesterol - Pancreatic Amylase: Digests carbohydrates - (All produced in the pancreas) (Site of action: Small intestine) - Small Intestine - Carboxypeptidase, Aminopeptidase, Dipeptidase: Digest Proteins - Lipase: Digests Lipids - Sucrase, Maltase, Lactase: Digests the simple carbohydrates sucrose, maltose, and lactose 11. What are accessory organs in digestion? List 3 accessory organs and their role in digestion. ****All three produce, store, and secrete enzymes and other chemicals that are involved in digestion**** 1. Gallbladder: - Stores Bile - Bile – A greenish fluid produced by the liver that emulsifies lipids 2. Pancreas: - manufactures, holds, and secretes digestive enzymes - stores enzymes in the inactive form – which is why as seen in #10 the site of action is not the pancreas but the small intestine - produces the hormones insulin and glucagon to regulate blood glucose - secretes bicarbonate to neutralize chyme 3. Liver - synthesizes chemicals for metabolism (such as Bile, for the emulsification of fat) - receives the products of digestion- releases glucose from glycogen storages - stores vitamins - manufactures blood proteins - filters the blood 12. Describe the anatomy of the small intestine. - The lining of the small intestine is heavily folded resulting in the increases surface area for the absorption of nutrients - The folds are covered with villi (finger like projections). - Each villus contains capillaries and a lacteal for picking up nutrients absorbed through the enterocytes and transporting them throughout the body - The cells on the surface of the villi are called enterocytes. - Enterocytes end in hair like projections called microvilli that together form the
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