Exam 2 Study Guide 1 Define hunger and appetite Which organ triggers feelings of hunger and satiation Hunger Physiological drive for food nonspecific can be satisfied with a variety of foods Appetite Physiological desire to consume specific foods aroused by environmental cues Hypothalamus triggers feelings of hunger or satiation fullness 2 What effect do different macronutrients have on hunger What type of food has the high est satiation value Proteins have the highest satiation value High fat diets have higher satiety than high carb diets 3 Define the processes of digestion absorption and elimination The Basic Stages of the Digestive Process 1 Ingestion the process by which food is taken into the alimentary canal It includes the processes that take place while the food is in the mouth mouth buccal cavity such as chewing and grinding using the teeth the lubrication and chemical effects of saliva re leased from the salivary glands and swallowing of the food which sends it onwards down the digestive tract 2 Digestion the process by which ingested food material is broken down in the earlier stages of the alimentary canal into a form that can then be absorbed and assimilated into the tissues of the body Digestion includes two types of processes Mechanical e g chewing grinding churning mixing and Chemical e g action of digestive enzymes bile acids etc The mechanical processes include the chewing and grinding of food by the teeth and also the churning and mixing of the contents of the stomach Chemical processes that contribute to digestion also begin in the mouth with action of saliva on food However most of the chemical digestive processes occur in the stomach and small intestine where the partly digested materials are subjected to gastric juices pancreatic juice succus entericus and so on 3 Absorption Assimilation process of taking molecules across a cell membrane and into the cells of the body Most absorption of nutrients takes place in the small intestine while a small amount occurs ion the stomach and large intestine 4 Types of Absorption in the Small Intestine 1 Passive diffusion nutrients simply pass through the enterocytes and into the bloodstream without the use of a carrier or energy no protein no energy 2 Facilitated diffusion requires a carrier protein no energy 3 Active Transport requires energy and a protein carrier to transport nutrients yes both pro tein and energy 4 Endocytosis active transport by which a small amount of intestinal contents is engulfed by the cell membrane into the cell Digested food which is referred to by other terms depending on its stage of passage through the digestive system see transit through the alimentary canal is absorbed into the bodily fluids blood and lymph from the alimentary canal Most of the absorption part of the digestive process occurs in the jejunum and the ileum of the small intestine though alcohol is readily absorbed through the stomach The small intestine is lined with minute finger like processes called villi a single example being a villus that greatly increase its surface area and hence the rate at which absorption can take place Assimilation is the process by which components chemicals from food incl liquid refreshments such as milk drinks fruit juices etc are taken into the cells of the body after the food beverage has been digested and absorbed 4 Elimination the final stage of this 4 stage summary of digestion In physiology more generally the term elimination can apply to the entire process of excretion of metabolic waste products incl from the blood via the kidneys and urinary tract as described in the section about the Renal System 4 Know the difference between peristalsis and segmentation They are both a type of mechanical digestion that is involved in the gastrointestinal tract GI tract Peristalsis the slow and gradual movement of food through the digestive system The food is crushed and propelled in one direction as smooth muscle contracts and forces the food along the gastrointestinal tract Peristalsis is not to churn but to slowly move food along towards the large intestine Segmentation the local mixing of food with enzymes and intestinal juices from pancreas etc The food is mixed and and exposed to absorptive cells as it moves along 5 Know the role of gastrin Gastrin is secreted by stomach lining cells that stimulates the gastric glands to produce gastric juice 6 Know the two different types of cells in gastric glands What is gastric juice and what is the role of each component of the gastric juice The two types of cells in gastrin glands are parietal cells and chief cells Gastric juice contains hydrochloric acid HCl pepsin gastric lipase and intrinsic factor Parietal Cells secret HCL and intrinsic factor Chief Cells secret pepsinogen and gastric lipase HCl denatures proteins and activates pepsin Pepsin enzyme to digest protein Gasrtric Lipase enzyme to digest fat Intrinsic Factor protein to adsorb vitamin B12 7 Know the role of bicarbonate in stomach and small intestine Bicarbonate neutralizes the acid 8 Know the enzymes produced in gastrointestinal tract mouth stomach and pancreas that facilitate the digestion of carbohydrates fats and lipids Mouth Enzyme Salivary amylase Digests Carbohydrates Stomach Enzymes Pepsin Digests Proteins Gastric Lipase Digests Lipids Pancreas Enzymes Proteases Digests Porteins Elastase Digests Fibrous Proteins Pancreatic Lipase Digests Lipids Cholesterol Esterase Digests Cholesterol Pancreatic Amylase Digests Carbohydrates 9 List the key hormones involved in digestion and their actions Gastrin stimulates secretion of HCl and pepsinogen Secretin Stimulates secretion of pancreatic bicarbonate which neutralizes acidic chyme Cholecystokinin CCK Stimulates secretion of pancreatic digestive enzymes stimulates gall bladder contraction slows gastric emptying Gastric Inhibitory Peptide GIP Inhibits gastric acid secretion slows gastric emptying stim ulates insulin release 10 List the accessory organs that facilitate digestion and their roles Accessory organs produce store and secrete enzymes and other chemicals that are involved in digestion Gallbladder stores biles which is released when signaled by CCK The bile emulsifies the lipids Pancreas Manufactures holds and secrets digestive enzymes Stores enzymes in the inactive form Insulin and glucagon are produced to regulate blood glucose Bicarbonate is secreted to neutralize chyme Liver Synthesizes chemicals for metabolism Receives the
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