Nutrition and Health Chapter 3 Notes
Nutrition and Health Chapter 3 Notes NTRI 2000
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This 7 page Class Notes was uploaded by Becky Stinchcomb on Sunday February 7, 2016. The Class Notes belongs to NTRI 2000 at Auburn University taught by Dr. B. D. White in Spring 2016. Since its upload, it has received 21 views. For similar materials see Nutrition and Health in Nutrition and Food Sciences at Auburn University.
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Date Created: 02/07/16
Nutrition and Health February 1, 2016 Cells - Cells are the basic unit of life - Each cell is a self- contained, living entity Cells: Specialized Structures - Cell membrane (separates the cell from extracellular fluids) - Intracellular fluid: cytoplasm - Mitochondria (“powerhouse of the cell”; has a double membrane structure; changes chemical bonds in carbohydrates, proteins, and fats into the currency of energy ATP) - Cell Nucleus (“brain”/ controller of the cell; contains DNA information/ blueprint of proteins) RNA - Endoplasmic Reticulum Smooth: fats, fatty acids Rough: ribosomes - Golgi Complex (where proteins are packed and shipped) - Lysosomes (waste processing) - Peroxisomes (contain hydrogen peroxide) Cell in its Environment Waste products Nutrients Cel l Sometimes carrier systems (active transport systems [go up a concentration gradient]) used to help move things across the cell’s membrane Facilitated diffusion (down a concentration gradient) Diffusion (down a concentration gradient) Phagocytosis (envelops the nutrient to become part of the cell) Multi- Cellular Organisms - Human body has somewhere between 10- 100 trillion cells - How do all of the cells obtain nutrients from their environment and then eliminate waste products? Levels of Organization of the Body - Tissues: cells of the same type join together using intercellular substances - Organs: one or more tissues combine together - Organ systems: various organs cooperate for a common purpose - Organism: combining of organ systems Every cell is not working independently; they work together for a common goal Some Organ Systems Related to Nutrition - Digestive - Cardiovascular - Respiratory - Urinary Cardiovascular - Consists of the heart, the blood vessels, and the blood - Heart: muscular pump of blood through the body Right side of the heart: pumps blood to lungs and then back to the heart Left side of the heart: pumps blood to all other parts of the body and back again - Arteries: blood vessels that leave the heart - Veins: blood vessels that return to the heart - Capillaries: “business end”; found in tissues; where the cells can be found - Where the exchange of nutrients, oxygen, and waste products occurs between the blood and the cells The small intestine is where we get most of our nutrient absorption in the digestive tract Capillaries - All of our cells are in direct contact with our capillaries - Forcing oxygen and nutrients into the interstitial fluid where they are metabolized and then released as waste products - PCOP (plasma proteins) forces the metabolizing of oxygen and nutrients to happen Lymphatic System - Helps carry fluid back to the cardiovascular system - Lymph: fluid that consists of plasma and white blood cells (and absorbed fat) - Eventually lymph drains back into the cardiovascular system near the heart Portal Circulation - Usually: artery capillaryvein - HOWEVER, between the small intestine and the liver: two capillary beds in the system Artery capillary portal vein capillary vein - Result: nutrients that are absorbed by the capillaries in the small intestine are first taken to the liver, not the heart Digestive System - Gastrointestinal Tract (GI Tract): a long tube that extends form the mouth to the anus (mouth, esophagus, stomach, small intestine, large intestine, rectum, anus) Where digestion and absorption of nutrients takes place - Accessory Digestive Organs: salivary glands, liver, gall bladder, pancreas Not directly contributing, but still important because they assist with easing digestion in the GI Tract Mouth - Tongue - Epiglottis: a little flap that covers both the esophagus and the trachea but helps when digesting food so that it goes down the correct tube - Larynx - Trachea: where food should not go because it leads to the lungs - Esophagus: where food should go because it leads to the stomach - Saliva: acts as a lubricant for the foods we eat Components of Saliva - Saliva Water Ions (includes bicarbonates that help neutralize the pH of the mouth) Antibodies (especially IgA and other antibacterial proteins) Enzymes (salivary amylase [helps with carbohydrates; not important in nutrition terms because it only works in a neutral pH and there isn’t a neutral pH in the human stomach] and salivary lipase [helps with lipids]) Esophagus - Muscular tube that connects the pharynx (throat) to the stomach - Peristalsis: a coordinated series of movements that help food move - Esophageal sphincter: at the connection of the esophagus and stomach; relaxes and allows food to enter the stomach; main job is to prevent backflow of the stomach contents Acid reflux (heartburn): when food contents come back through the esophageal sphincter and re-enter the esophagus Stomach - A large sac for holding food - Not a lot of digestion actually happens here - Contains gastric juice (water, hydrochloric acid, and enzymes) Hydrochloric acid: denatures proteins so that they can be used throughout the entire body and at different times - Also contains an intrinsic factor - Muscles of the stomach churn gastric contents into chyme - Pyloric sphincter: found at the other end of the stomach; controls the rate of chyme entering the small intestine; helps keep contents in the stomach but releases small amounts of chyme at a time - What keeps the stomach from digesting itself? Stomach is lined with a thick layer of mucus so that the gastric juice won’t come into contact with the stomach. Also, HCL (hydrochloric acid) and enzymes are primarily released only upon eating Small Intestine - Site of most of the digestion and absorption of nutrients - Intestinal hormones that are released: Secretin: releases bicarbonate from the pancreas Cholecystokinin (CCK): releases digestive enzymes from the pancreas Also contracts the gall bladder with release bile into small intestine Bile is important in the digestion of fats Bile is made in the liver - Because of folds in mucosa (the cells that line the small intestine on the inside), villi, and microvilli on cells, the surface area for absorption is huge - Water- soluble compounds are absorbed into the capillaries - Fat- soluble compounds are absorbed into lymph - Undigested food passes on the large intestine via the ileocecal sphincter Large Intestine - Only a minor amount of carbohydrates, protein, and fats escape absorption and reach the large intestine - Some absorption of water, some vitamins, some fatty acids, and the minerals sodium and potassium - Home to a large population of bacteria (over 500 species) - As water is absorbed, contents become semisolid - Becomes feces (water, undigested fiber, tough connective tissue, bacteria, dead intestinal cells, and body waste) - Contractions occur as mass movements - Rectum fills Defecation - Vasalva Maneuver Builds up to intra-abdominal pressure Straining to defecate can, over time, lead to diverticulosis Urinary System - Kidneys, ureter, bladder, urethra Used in the formation of vitamin D Produces a hormone, erythropoietin, that stimulates production of red blood cells Helps regulate blood pressure and fluid movement - Kidneys: produce urine, which is a modified ultrafiltrate of the blood - Functional unit of the kidney called the nephron Involved in the processes of filtration, reabsorption, and secretion Cell- to- Cell Communication - Nervous System - Endocrine System Nutrient Storage in the Body - Energy Glycogen: stored mainly in skeletal muscle and liver Fats (triglycerides): stored in adipose tissue around the body and also in other tissues
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