Science of NutritionExam 2- Chapters 3-7, 4.5By: Alyssa Kosh1Chapter 3:The Human Body: Are We What We Really Eat?A. Why do we want to eat what we want to eat?~Hunger- a physiologic sensation that prompts us to eat-the drive is nonspecific, a variety of foods could satisfy you~Appetite- a psychological desire to consume specific foods-the desire is specific to certain foods such a popcorn at the movie theatreor the sight of chocolate cake2Roles in Digestion:~Hypothalamus- triggers feelings of hunger or satiation (fullness)- integrates signals from nerve cells in other body regions and from chemical messengers called hormones~Sphincters- muscles that control the passage of food material from one GIT organ to the nextThe order of digestion in the GI Tract:- the mouth, esophagus, stomach, small intestine, large intestine, anus- accessory organs include:o pancreas,- manufactures, holds, and secretes digestive enzymeso liver- synthesizes chemicals for metabolism, stores vitamins, filters the blood removing wastes and toxins o gallbladder- stores bileFood undergoes three processes:- Digestion- large food molecules are broken down into smaller molecules, mechanically and chemically- Absorption- process of taking these products through the intestinal wall- Elimination- undigested portions of food and waste products are removed from the bodyDigestion in the Mouth:~Chewing- breaks up food and begins mechanical digestion-Epiglottis- covers the opening to the trachea during swallowing~Taste and Olfactory Receptors- detect distinct tastes such as bitter, sweet, salty, etc, and detects aromas of food.~Saliva- contains digestive juices secreted by the salivary gland in the mouthDigestion in the Stomach:~Gastrin: a hormone secreted by the stomach lining cells that stimulates the gastric glands to produce gastric juice~Gastric Juice- Acidic liquid secreted in the stomach - Contains hydrochloric acid, pepsin, and other compoundso hydrochloric acid- denatures proteins and activates pepsino pepsin- enzyme to digest proteino gastric lipase- enzyme to digest fato intrinsic factor- protein to absorb vitamin B12~Gastric Glands:- parietal cells- secrete HCL and intrinsic factor- chief cells- secrete pepsinogen and gastric lipaseDigestion in the Small Intestine: duodeum, jejunum, and ileum3~Chyme- liquid product of mechanical and chemical digestion in the stomach~Mucus- layer protects the stomach lining from the acid in gastric juices~Bicarbonate- neutralizes the acid~Ileocecal Valve- connects the small intestine to the large intestineDigestion in the Large Intestine (Colon):~ Its main function is to store indigested food material and absorb water, short-chain fatty acids, and electrolytes.~Hydrolysis- a chemical reaction that breaks down substances by addition of waterHormones Involved in the Regulation of Digestion:~Gastrin- produced in the stomach~Secretin- produced in the small intestine ~Cholecystokinin (CCK)- produced in the small intestine~Gastric Inhibitory Peptide- produced in the small intestineFour types of Absorption occur in the Small Intestine:~Passive Diffusion- nutrients simply pass through the enterocytes and into the bloodstream without the use of a carrier or energy~Facilitated Diffusion- requires a carrier protein and does not require energy ~Active Transport- requires energy and a protein carrier to transport nutrients~Endocytosis- active transport by which a small amount of intestinal contents isengulfed by the cell membrane into the cellMuscles of the Gi Tract:~Peristalsis- waves of squeezing and pushing contractions that move food, chyme, and feces in one direction through the length of the GI tract.~Segmentation- rhythmic contractions of circular muscles in the intestinal wall~Haustration- segmentations in the colon that contract sluggishly to move contents, located in the colon~Mass movement- occasionally occurs to move wastes toward the rectumMuscle contractions in the GI Tract:~Stomach- 2 times per minute~Small intestine- up to 10 times per minutes~Haustra- 2 times per hourDisorders related to:~Digestion, absorption and excretion:~Heartburn- the painful sensation that occurs over the sternum when hydrochloric acid backs up into the lower esophagus~GERD- a painful type of heartburn the occurs more than twice per week~Peptic ulcer- An area of the GI tract that has been eroded away by the acidic gastric juice of the stomach. 4~Specific foods:~Food intolerance: gastrointestinal discomfort caused by certain foods that is not a result of an immune system reaction~Food allergy- An allergic reaction to food, caused by a reaction of the immune system.~Celiac disease- a disorder characterized by an immune reaction that damages the lining the small intestine when the individual is exposed to a component of a protein called gluten.~Inflammatory disorders:~Crohns disease: a bowel disease that causes inflammation in the small intestine leading to diarrhea, abdominal pain, rectal bleeding, weight loss, and fever~Ulcerative colitis: A chronic disease of the large intestine, or colon, indicated by inflammation and ulceration of the mucosa, or innermost lining of the colon.~ Functional Disorders:~ Diarrhea: A condition characterized by the frequent passage of loose, watery stools.~Constipation: a condition characterized by the absence of bowel movements for a period of time that is significantly longer than normal for the individual.Chapter 4:Plant- Derived Energy NutrientsWhat are Carbohydrates?~Macronutrient~Carbon, Hydrogen, Oxygen~Glucose- the most abundant carbohydrate- Produced by plants through photosynthesis~Simple Carbohydrates-contain one or two molecules-commonly referred to as simple sugars- can increase “bad cholesterol”- can decrease “good cholesterol”- Monosaccharides- contain one moleculeo Glucose, fructose, galactose- Disaccharides- contain two moleculeso Lactose, maltose, and sucrose5- Alpha bond- a type of chemical bond that can be digested by enzymes found in the human intestine- Beta Bond- a type of chemical bond that cannot be easily digested by enzymes found in human intestine.~Complex Carbohydrates ~Starch, glycogen, most fibers~Oligosaccharides- Contain 3-10 molecules~ Polysaccharides- Consist of hundreds to thousands of glucose molecules~ Starch: Polysaccharide stored in plants- Amylose: straight chain of glucose- Amylopectin: branched chain of glucose~ Glycogen: storage form of glucose for animals- Not a source of dietary carbohydrate- Stored in the liver
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