Chapter 3: The Human Body
Chapter 3: The Human Body NTRI 2000-002
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This 5 page Class Notes was uploaded by Kaylen Taylor on Sunday January 31, 2016. The Class Notes belongs to NTRI 2000-002 at Auburn University taught by Michael Winand Greene in Fall 2015. Since its upload, it has received 58 views. For similar materials see Nutrition and Health in Nutrition and Food Sciences at Auburn University.
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Date Created: 01/31/16
Chapter 3: The Human Body Friday, January 29, 2016 7:39 PM Cell in its environment Cells are the basic unit of life. Each cell is a self-contained, living entity. Cells take nutrients and excrete waste products. Cell Metabolism Entire collection of chemical processes involved in maintaining life. Biochemical reactions take place in the cell cytoplasm and organelles. Enzymes mediate these functions. Anabolic requires energy. Catabolic takes molecules apart and releases energy. Multicellular Organism Same issues as a cell. Whole body metabolism is similar to a cell's. Takes nutrients in, excretes waste products. Levels of Organization Chemical level: Atoms combine to form molecules. Cell Level: Molecules for organelle. Tissue Level: cells form together to make tissues. Organ Level: Tissues come together to make organs Organ System Level: Organs come together to make organ systems. Organism: Organ systems come together to make the organism. Cardiovascular System Carries blood Regulates blood supply Transports nutrients, waste products, cells, and gases. Regulates blood pressure. Plays a role in immune responses and body temperature. Components: o Heart: muscular pump of blood. o Blood Vessels: "Pipes" that blood flows through Arteries: takes blood away from the heart Veins: Returns blood to the heart. o Capillaries o Blood: Made of plasma, red and white blood cells, and platelets. Red blood cells: carry oxygen through the body White blood cells: defend body by fighting infection. Plasma: Carries nutrients, hormones and proteins through the blood. Platelets: regulates blood clotting Capillary Function o Exchange between blood and cells Nutrients Oxygen Waste products Blood flows from artery→ capillary→ vein Portal Circulation o Artery → capillary→ vein→ portal vein→ capillar→ vein o Nutrients absorbed by capillaries in the small intestines Go to the liver and not the heart Portal vein connects the small intestine to the liver. Lymphatic System o Brings fluid (lymph) back to the cardiovascular system. Lymph contains plasma. White blood cells (and absorbed fat) Lymph nodes: stores immune cells o Drains back into the cardiovascular system near the heart, and the heart pumps it back around. o Function: Removes foreign substances from blood and lymph. Helps to maintain tissue fluid balance. Aids in fat absorption. Immune functions: provides Defense against pathogens Produces white blood cells Endocrine System o Major Components: Endocrine glands: Pituitary glands Thyroid glands Adrenal glands Hypothalamus Pancreas Hormones are produces in the endocrine glands. Hormones are messengers that communicate from the glands to different parts of the body. Hormones act locally as well as all over the body. o Function: Major role of regulation of metabolism, reproduction, water balance, and many other functions. Produces hormones in the endocrine glands Hormones are messenger Endocrine- Circulating through body Paracrine- Acting close by Autocrine- Acting on cell that produces the hormone Can hormones be produced in other cells and organs? Yes. Endocrine vs. Exocrine Systems o Within the pancreas, we have exocrine cells that secrete digestive enzymes that are put into a duct which leads to the small intestine. o In the Pancreatic islet, endocrine cells secretes hormones into the blood. Digestive System o Gastrointestinal tract Tube Mouth to Anus Digestion and absorption of nutrients o Accessory Digestive Organs Salivary Glands Liver Gall bladder Pancreas o Mouth Epiglottis: helps food go down the correct tube, which is the esophagus. o Esophagus A muscular tube connecting the pharynx (throat) to the stomach. The food moves by a series of coordinated contractions known as peristalsis. Esophageal sphincter: Relaxes, allowing food to enter the stomach. Prevents backflow of food. o Stomach A large sac that holds food. Contains gastric juice (water, HCl, and enzymes) and also an intrinsic factor (Helps out with b12) Muscle of the stomach churn gastric contents into chyme. Pyloric sphincter controls the rate of chyme entering the small intestine. What keeps the stomach from digesting itself? Mucus: The stomach is lined with a thick layer of mucus so gastric juice doesn’t come into contact with the stomach. HCl and enzymes are primarily released upon eating. o Small Intestine Principle site for absorption and digestion of nutrients. Intestinal hormone are released to help with digestionand absorption of chyme. Secretin: Releases bicarbonate from pancreas. This helps neutralize the acid. Cholecystokinin (CCK): Releases digestive enzymes, regulates the release of bile from the gall bladder into the small intestine. Bile is made in the liver, and is important in the digestion of fats. The small intestine is efficient in absorption because of the many "folds" in it. These folds are called villi and microvilli. They increase the surface area so your intestine can be much more efficient at absorption. Capillaries absorb water soluble compounds. Fat soluble compounds are absorbed into the lymph. Undigested food passes on into the large intestine. Ileocecal Sphincter: Controls movement of undigested food from small intestine to the large intestine. o Nutrient Absorption Passive Absorption (Diffusion) Concentration dependent Facilitated Absorption (Transport) Carrier or receptor dependent. These are specific for different types of nutrients. Active Absorption Carrier/receptor and energy dependent. Phagocytosis/Pinocytosis Form of active transport. Basically grabs whatever nutrients are there. Not specific. Happens in small intestine as well. o Large Intestine Only a minor amount of carbs, protein, and fats that escape absorption in the small intestine and reach the large intestine. No villi or enzymes. 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) More bacteria cells in your colon than in the rest of your body. As water is absorbed, contents becomes a semisolid. Becomes feces (water, undigested fiber, tough connective tissue, bacteria, dead intestinal cells, and body wastes.) Contractions occur as a mass movement, filling the rectum. Anal sphincters control waste movement from large intestine through to the anus. Accessory Organs for Digestion o Gallbladder Organ attached to the underside of the liver; stores bile, concentration, and secretion. Is green in color. o Bile Released through common bile duct into the first segment of small intestine. Essential for digestion and absorption of fat. o Enterohepatic circulation Continual recycling of compounds like bile acids between small intestine and liver. o Liver Releases a number of unwanted substances that travel with bile to gallbladder. Substances end up in the small intestine, and eventually in the large intestine for excretion. o Pancreas Has both endocrine and digestive functions Manufactures hormones: Insulin and Glucagon Produces "pancreatic juice", which is a mixture of water, bicarbonate, and a variety of digestive enzymes. o Digestive Disease Case: An elderly woman sees her doctor and complains of pain two hours after eating, weight loss, nausea, vomiting, and loss of appetite. Diagnoses: Ulcers Can actually come from bacteria (Helicobacter pylori) Discovered by Barry Marshall and J. Robin Warren Causes an infection that damages the stomach mucus, causing holes to form. Treatment: Antibiotics Gastroesophageal Reflux Disease Heartburn Half of US adults experience occasional heartburn Also called acid reflux Can damage the lining of the esophagus Constipation Difficult or infrequent evacuation of the bowels. Treatment Increasing fiberintake Stimulates peristalsis Dried fruits Drinking water Relaxation/Regular exercise Probiotics and laxatives can lessen constipation Consult a health professional before using Irritable Bowel Syndrome Symptoms: Cramps, gassiness, bloating, irregular bowel function, diarrhea, constipation, or alternating episodes of both. Visible abdomen distention Hard to pinpoint exact causes Altered intestinal peristalsis Decreased pain threshold Treatment: Elimination diet, moderate caffeine, low-fat, small, frequent meals, stress reduction Celiac Disease and Gluten Sensitivity Chronic, immune-mediated disease precipitated by exposure to dietary protein gluten Genetic pre-disposal Found in certain grains, wheat, rye, barley Affects about 1% of the US Flattens the villi, causing less surface area, which limitsnutrient absorption. Treatment: Should include a blood test for antibodies to gluten Eliminate gluten filled foods. Urinary System o Kidneys, ureter, bladder, urethra Kidneys: Produce urine, which is a modified ultra-filtrate or blood. Functional unit of the kidney is called the nephron. Nephron is involved in the processes of filtration, reabsorption, and secretion. Kidneys are also used in vitamin D formation, produces the hormone erythropoietin, which stimulates the production of red blood cells, and helps regulate blood pressure and fluid balance. Central Dogma of Biology o DNA → RNA → Protein The Emerging Field of Genomics in Nutrition o Nutritional Genomics Interactions between nutrition and genetics Variations in nutrient requirements. Responsiveness to dietary modifications Impact of food on gene expression Our susceptibility to nutritionally related diseases