Chapter 21 - BIOL1320
Chapter 21 - BIOL1320 BIOL 1320
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This 8 page Class Notes was uploaded by Ailia Owen on Wednesday March 4, 2015. The Class Notes belongs to BIOL 1320 at University of Houston taught by Brian C Mahon in Spring2015. Since its upload, it has received 189 views. For similar materials see General Biology in Natural Sciences and Mathematics at University of Houston.
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Date Created: 03/04/15
CH 21 Nutrition and Digestion 3415 442 PM All animals must eat to provide 0 Energy 0 Building blocks to assemble new molecules 0 Essentials vitamins and minerals Humans Developed countries cheap calorie dense food short less active lives 0 Combined with sedentary jobs and inactivity leads to obesity US 68 of people are overweight 100 million obese OBTAINING AND PROCESSING FOOD 3 diets o Herbivores eat plants cattle snails sea urchins Longer digestive tract Specializations in the gut that promote growth of cellulose digesting bacteria and protists n Lack enzymes needed to digest cellulose in plants a Cecum coyote and koalas a Large intestine and cecum rabbits n Stomach ruminants cow sheep deer o Carnivores eat meat lions hawks spiders o Omnivores eat both plants and animals humans roaches raccoons crows Obtaining food 0 Suspension feeders sift small organismsfood particles from water 0 Substrate feeders live inon food and eat their way through it caterpillars o Fluid feeders suck nutrientrich fluids from living host mosquitos 0 Bulk feeders ingest large pieces of food pelican Processing food 0 Ingestion eating 0 Digestion breaking down food into molecules small enough for the body to absorb Mechanical chewing Chemical hydrolysis n Protein gt protein digesting enzymes gt amino acids n Polydisaccharides gt Carbohydrate digesting enzymes gt monosaccharaides n Nucleic acid gt nucleicacid digesting enzymes gt nucleotides a Fat gt fat digesting enzymes gt Glycerol and fatty acids Compartments vacuole organelle in cell a Gastro vascular cavity one opening mouth to take in food and eliminate waste a Alimentary cavity mouth ingestion and anus elimination One way flow of food beginning to end 0 Pharynx throat o Esophagus down to Crop food softened and stored Gizzard food ground and stored Stomach food ground and stored o Intestines chemical and nutrient absorption 0 Anus undigested food expelled 0 Absorption take up products of digestion usually by cells lining digestive tract 0 Elimination removal of undigested materials out of digestive tract THE HUMAN DIGESTIVE SYSTEM Length diet Herbivores and omnivores longer Carnivores shorter 0 Oral cavity ingested and chewed in the mouth 0 Mechanical chewing breaking up to swallow easier 0 Tongue tastes and pushes food to pharynx Bolus shaping of food into a ball 0 Teeth incisors canine premolars molars wisdom o Salivary glands Glycoprotein moistens and lubricates food Buffers neutralize acids Salivary amylase begins enzymatic hydrolysis of starch Antibacterial agents kill bacteria in food throat air moves to o Larynx gt past vocal cords in voice box gt trachea gt lungs o Epiglottis small flap tip of larynx prevents food from getting into trachea windpipe Esophagus Pharynx o Swallowing reflex Starting Epiglottis up larynx down Esophageal sphincter contracted Swallowing Epiglottis down larynx up esophageal sphincter relaxed Completed Epiglottis up larynx down Esophageal sphincter contracted o Peristalsis waves of contraction and relaxation of smooth muscle along walls to push food down 0 Stomach can stretch and store up to 2L of foodliquid o Sphincters how food enters and exits rings of muscle that cinch between compartments 0 Lumen cavity 0 Chemical digestion Gastric juice n Mucus n Proteindigesting enzyme pepsinogen a Strong acid HCL pH of 2 kills bacteria breaks food cells denatures proteins Gastric gland top to bottom a Pit opening in interior surface a Epithelium n Mucous cells a Chief cells releases pepsinogen n Parietal cells releases HCL HCL Pepsinogen Pepsin active enzyme a Secreted into lumen a Chain reaction pepsin activates release of pepsinogen n Pepsin begins chemical digestion o Preventing stomach lining Pepsin inactive form protects Mucus protects against HCL and pepsin New cells every 3 days 0 Ailments Acid reflux chyme comes up into esophagus Gastroesophageal reflux GERD frequent severe acid reflux Ulcers sores in stomach lining Bacterial infection Helicobacter pylori can produce ulcers 0 Small intestine final steps of digestion and absorption Named for small diameter 6 meters long Surface area increased by folds in lining villi microvilli projections on surface of intestinal cells Duodenum first 25 cm chyme squirts from stomach mixing with digestive juices from Pancreas pancreatic juice mix of digestive enzymes and an alkaline solution rich in bicarbonate Liver produces bile breaks up fat into small droplets making them more susceptible to attack by digestive enzymes n Hepatic portal vein blood from digestive tract drains to liver n Converts glucose in blood to glycogen stores and releases back to blood a Synthesizes proteins bloodclotting and lipoproteins transport fat and cholesterol to body cells n Modifies substances in digestive tract to less toxic forms Gallbladder stores bile Intestine wall produces digestive enzymes Enzyme digestion Carbs Polysaccharides gt pancreatic amylase gt Maltose other disaccharides gt Maltase sucrase lactase gt Monosaccharaides Proteins Polypeptides gt trypsin chymotrypsin gt smaller polypeptides gt various peptidases gt amino acids Nucleic acids DNA amp RNA gt Nucleases gt Nucleotides gt other enzymes gt Nitrogenous bases sugars phosphates Fat Fat globules gt bile salts gt fat droplets emulsified gt lipase gt Fatty acids and glycerol Absorption Nutrients pass into epithelial cells by diffusion and against concentration gradients Fatty acids and glycerol recombined into fats coated with proteins and transported to lymph vessels Amino acids and sugars out of intestinal epithelium gt across capillaries into blood gt to liver Large intestine colon undigested food 0 15 m long 5cm diameter o Cecum pouch nearjunction with small intestine Appendix fingerlike extension 0 Contains E coli produce important vitamins Absorbs vitamins and water into blood 0 Diarrhea too little water reclaimed from LI 0 Constipation too much water reclaimed from LI Rectum feces stored Anus feces expelled Heimlich maneuver Forceful elevation of the diaphragm Pushing air into trachea Dislodges food from tracheapharynx Brain damage in minutes of restricted airways N UTRITION All animals have similar nutritional needs 0 Fuel to power all body activities 0 Organic molecules to build animal s own molecules 0 Essential nutrientssubstances the animal cannot make for itself Cellular respiration produces the body s energy currency ATP 0 Oxidizing organic molecules from food 0 Carbsfat fuel Gram of fat more then 2X calories as gram of carbprotein Kilocalories 1000 calories energy content measurement of food 0 Dietary calories are kCal written as cal Metabolic rate rate of energy consumption 0 The sum of all energyrequiring biochemical reactions over a given period of time o BMR energy for physical activity 0 Excess energy stored as glycogenfat Basal Metabolic Rate BMR required resting energy Essential nutrients cannot be made from any raw material 0 Essential fatty acids linoleic acid Make phospholipids of cell membranes Seeds grain vegetables 0 Essential amino acids Make proteins Meats eggs milk o Vitamins organic nutrients Water soluble Blthiamine Pork legumes whole grains peanuts Remove C02 from organic compounds Beriberi tingling poor coordination reduced heart function BZriboflavin Dairy meats grains Component of FAD Skin lesions 33niacin Nuts meats grains Component of NAD and NADP Skin and gastro lesions delusions confusion BSpantothenic acid Meats dairy whole grains fruits vegies Component of A Fatigue numbness tingling handsfeet B6pyridoxine Meats vegies whole grains Coenzyme in amino acid metabolism Irritability convulsions muscular twitch anemia B7biotin Legu mes vegies meats Synthesis of fat glycogen amino acids Scaly skin neuromuscular disorders 39folic acid Green vegies oranges nuts legumes Nucleic acid and amino acid metabolism Anemia birth defects BlZcobalamine Meats eggs dairy Production of nucleic acid and RBC Anemia numbness balance loss BlSascorbic acid Citrus fruit broccoli CoHagen synthesis antioxidant Scurvy delay wound heaHng Fat soluble A D E K A retinol Dark greenorange veggies Visual pigments maintain Blindness skin fruits dairy epithelia tissue disorder impaired immunity D Dairy egg yolk Absorption and use of Rickets children calcium and phosphorus bone softening aduks E tocopherol Vegie oil nuts seeds Antioxidant prevent cell Nervous system membrane damage degradation K Green vegies tea colon Blood clotting Defective blood bacteria clotting 0 Minerals simple inorganic nutrients Calcium and phosphorus required in large amounts Iron hemoglobin Iodine thyroid hormone Most ingest more salt then needed 0 Vitamins and minerals Required in minute amounts Essential to good health Overdoses can be harmful n Excess WS eliminated in urine n Excess FS accumulate to toxic levels 0 Cholesterol 0 Lowdensity lipoproteins LDL contribute to Blocked blood vessels High blood pressure Trans fat increase levels Consuming mainly unsaturated fats lower levels 0 Highdensity lipoproteins HDL help reduce blocked blood vessels Exercise increases levels Smoking decreases levels 0 Malnutrition chronic deficiency in calories or 1 essential nutrients 0 Protein deficiency most common 0 Occurs when Diets do not supply enough chemical energy Someone suffers from anorexia nervosabulimia 0 Recommended Dietary Allowances RDA 0 Minimum amounts of nutrients that are needed each day 0 Determined by national scientific panel Epidemiology study of human health within a population 0 Sailors need for Vitamin C o Newborns folic acid to prevent neural tube defect in women in low socioeconomical status 0 Food labels indicate 0 Serving size 0 Caloriesserving 0 Amounts of selected nutrientsserving as daily values 0 Recommendations for daily limits of selected nutrients Overnutirition more food for energy consumed then needed 0 Obesity excess accumulation of fat World Health Organization obesity major health problem Why n Lack of exercise a Amount and quality of food Leads to a Type 2 diabetes a Cancer colon breasts n Cardiovascular disease 0 US 30 obese 35 overweight Adolescents 15 obese 17 overweight 300000 deathsyear obesity surpasses smoking in contribution to disease and shortening of life spans market for weight loss a 1999 60 million a today 48 billion 0 Leptin weight control Produced in fat cells Suppresses appetite Obese children with mutated leptin gene lose weight after leptin treatment High levels of healthy people do not suppress appetie
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