Science of Human Nutrition
Science of Human Nutrition 23511
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This 7 page Class Notes was uploaded by Layne Henwood on Sunday March 6, 2016. The Class Notes belongs to 23511 at Kent State University taught by Carmen Blakely-Adams in Spring 2016. Since its upload, it has received 54 views. For similar materials see Science of Human Nutrition in Nutrition and Food Sciences at Kent State University.
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Date Created: 03/06/16
Chemical, Biological and Physiological Aspects of Nutrition How do biological molecules form cells, tissues, organs and organ systems? Cells o Organelles, cytoplasm, extracellular and intracellular environments o Cell membranes Selectively permeable Transport mechanisms Passive transport mechanisms Does not require energy (ATP) Simple diffusion (high to low concentration) Facilitated diffusion Requires some type of assistance (transport protein) Osmosis solutes (substances able to be dissolved in a fluid) Active transport mechanisms Requires energy (ATP) Carrier-mediated active transport Vesicular active transport Endocytosis Exocytosis Four basic types of tissues Epithelial tissue o Covers and lines body surfaces, organs and cavities o Protect you o Can be damaged by cuts, scrapes, burns etc. Connective tissue o Provides structure to the body by binding and anchoring body parts Muscle tissue o Contracts and shortens when stimulated o Plays an important role in movement Neural tissue o Plays a role in communication by receiving and responding to stimuli o Responds to stimulation o Ex. touching something hot or very cold Tissue Layers Mucosa o Mainly epithelial cells o GI secretions o Lifespan of 2-5 days, then rejuvenates Submucosa o Surrounds mucosa o Rich supply of blood vessels o Lymphatic vessels Help circulate things that aren't water soluble o Network of nerves Muscularis o 2 layers of smooth muscle Longitudinal layer and circular layers o Mixing of foo mass with digestive secretions Serosa o Secretes fluid that lubricates digestive tract organs o Does not allow digestive organs to fuse together Organ systems and related to major functions Circulatory system o Heart, blood vessels, blood, lymph vessels, lymph nodes and lymph organs o Transports nutrients, waste products, gases Digestive system o Mouth Breaks up food particles Assists in producing spoken language o Salivary glands Saliva moistens and lubricates food Amylase digests polysaccharides o Pharynx swallows o Esophagus Transports food o Liver Breaks down and builds up many biological molecules Stores vitamins and iron Destroys old blood cells Destroys poisons Bite aids in digestion Bile made in liver and stored in the gall bladder o Gallbladder Stores and concentration bite Bile is made in the liver but stored in the gall bladder o Stomach Stores and churns food Pepsin digest protein HCI activates enzymes, breaks up food, kills germs Mucus protects stomach wall Limited absorption Very acidic Bolus becomes liquefied and becomes Chyme o Pancreas Hormones regulate blood glucose levels Bicarbonates neutralize stomach acid Trypsin and chymotrypsin digest proteins Amylase digests polysaccharides Lipase digest lipids o Small intestine Major organ for absorption Completes digestion Mucus protects gut wall Absorbs nutrients, most water Peptidase digests proteins Surceases digest sugars Amylase digests polysaccharides o Large intestine Reabsorbs some water and ions Forms and stores feces o Rectum Stores and expels feces o Anus Opening for elimination of feces Transit times o 24-72 hours o Factors affecting transit time Sphincters o Named according to anatomical locations o Gastroesophegeal sphincter Between esophagus and stomach Relaxes briefly to allow food to enter the stomach then closes GI motility o Mixing and propulsion of material Muscular contractions o 2 types of movement Segmentation Mixes and propels food Peristalsis Vigorous propulsive movements How do Gastrointestinal Motility and Secretions Facilitate Digestion? GI Secretion o Mucus Protective coating o Digestive enzymes Biological catalysts o Organs that release digestive secretions Salivary glands, stomach, pancreas, liver How does the GI Tract coordinate functions to optimize digestion and nutrient absorption? Three phases of digestion o Cephalic phase Before food enters mouth Things you are thinking about before eating Things you smell or see o Gastric phase Arrival of food in stomach Manipulate bolus into liquid Chyme o Intestinal phase Primarily absorption and elimination Digestion begins in the mouth o Mastication o Saliva o Taste sensation Salty, sweet, sour, bitter, unami (beefy, savory flavor) o Olfactory and gustatory cells o Swallowing Phases Bolus o Esophagus Delivers food to the stomach Dysphagia Swallowing difficulties Gastroesophegeal sphincter Between esophagus and stomach Opens and closes to keep acidic contents from coming back up Transit time Less than 10 seconds From phrenic to stomach o Stomach Regions Fundus, body, antrum Pyloric sphincter Regulates flow of chyme from the stomach into the small intestine Storage Rugae Reason stomach can stretch Mixing food with gastric secretions Third layer of smooth muscle Chyme Peptic ulcers Types Helicobacter pylori (H. pylori) 80% of people that have them it is not because of what they are eating or stress from this Caused by a bacteria Symptoms Pain Weight loss Poor appetite Gastroesophageal reflux disease (GERD) Gastroesophageal sphincter functions improperly Symptoms Diagnosis o Regulation of gastric emptying Influential factors Volume- how much? Consistency- ice cream vs. steak Composition of chyme Influence of small intestine Cholecystokinin (CCK) Tells stomach to stop moving and when to move o Small intestine Chemical digestion and nutrient absorption Maximum amount of absorption Regions Duodenum (1st part), jejunum and ileum (end) Lining of small intestine Plica circulates Villi Enterocytes Hair like projections that help absorb nutrients (look like fingers moving), no absorption when they stop moving Very important Microvilli Lacteal Help absorb nutrients insoluble in liquids Ex. Fat Digestion in the small intestine o Regulated by hormones Secretin and CCK o Pancreatic juice o Bile Produced in liver, stored in gallbladder Digestion of fatty foods Enterohepatic circulation o Enzyme facilitation o Bioavailability Cardiovascular System o Two loops o Systemic circulation Delivers blood to all the body's organs except lungs o Capillaries Exchange of materials, nutrients, and gases o Arterial and venous vascular systems Similarities and differences Lymphatic System o Circulates fat-soluble nutrients Eventually delivers them to cardiovascular system o Route initially bypasses the liver Kidneys o Cellular waste products o Nephrons Filtration Initially removes substances from the blood Reabsorption o Causes impaired kidney functions Hemodialysis o Formation of urine What is the Role of the Large Intestine? Major functions o Absorption and reabsorption o Microbial action o Storage and elimination Four general regions o Cecum Appendix Ileocecal sphincter o Colon Ascending, transverse, descending o Rectum o Anal canal Internal and external anal sphincters Absorption and reabsorption o Haustral contractions o Absorption Some water and electrolytes o Reabsorption GI secretions o Feces Diarrhea and constipation Microbial action o Intestinal microbiota More than 400 species o Important roles o Probiotic and prebiotic foods Egestion o Defecate Irritable Bowel Syndrome and Inflammatory Bowel Disease Inflammatory bowel disease (IBD) o Autoimmune disease Ex. Crohn's disease, Ulcerative colitis Irritable bowel syndrome (IBS) o Functional disorder o Underlying cause has not been determined
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