Nutrition: Chapter 3Digestion - Processes by which food you eat is broken down into components small enough to be absorbed into the bodyAbsorption - The processes of taking substances (nutrients) from the digestive system into the interior ofthe bodyGastrointestinal Tract - Continuous tube from the mouth to the anus Path is mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anusLumen - Inside the tube; lined with a layer of mucosal cellsAccessory organs - Salivary glands, liver, gall bladder and pancreasMucus - Secreted from mucosal cells lining the digestive tract; it moistens, lubricates, and protectsEnzymes - Protein-molecules that speed up reactions; in the digestive tract, they help breakdown larger molecules of food into smaller onesHormones - In the digestive tract, regulate digestion and rate at which food moves through the GIMouth - mechanical and chemical digestion begins; tongue, chewing, salivaSaliva - helps starting the chemical digestion; contains the enzyme amylase: breaks down starch into shorter sugar chainsPharynx - Responsible of swallowing (food pass through); part of digestive and respiratory systemEpiglottis - Blocks food from entering the trachea and lungs during swallowingEsophagus - Moves bolus of food through a series of coordinated muscle contractions & relaxations called peristalsis; food passes through a muscular ring called a sphincter at the end of the esophagus to enter the stomachStomach - Temporary storage of food; result in chyme; very little absorption; regulated by signals from the small intestines and is affected by meal size and compositionGastric juice - secreted and continues the process of chemical digestion; components are water, hydrochloric acid, pepsinogen, mucusHydrochloric Acid - Kills microorganisms, inhibits amylase, helps digestion of proteins with activation of pepsin and unfolding proteinsMucus in stomach - Protects stomach lining from pepsin and hydrochloric acidSmall intestine - Mechanical digestion through local contractions mixes chyme with digestive juices; chemical digestion of carbohydrates, proteins, lipids, and nucleic acids is completed; provides primary surface for absorption of nutrients and waterPancreas - secretes pancreatic juice containing bicarbonate, pancreatic amylase, pancreatic proteases, pancreatic lipasesIntestinal glands - secretes intestinal enzymes to aid breakdown of double sugars into simple sugars and break down of short chains of amino acids to single chains of amino acidsLiver - Produces bileGallbladder - stores bile and secretes bile into small intestineBicarbonate - neutralizes stomach add gastric juicesBile - emulsifies far so lipases can access fat moleculesLarge intestine - Ends at the anus; absorption of water, some vitamins and minerals; bacteria, intestinal micro-flora, digest some nutrients and make it vitamin K and some B vitamins; rectum stores fecesSimple diffusion - A substance crosses a cell membrane by moving from a higher concentration to a lower concentration; energy not required (vitamins and fatty acidsFacilitated diffusion - A substance crosses a cell membrane with the assistance of a transport protein; energy not required (fructose)Osmosis - Water crosses cell membranes freely; moves from a lower solute concentration to a high solute concentration till it is the same on both sides; energy not requiredActive transport - Energy required (Sodium ion, glucose, amino acids)Bloodstream transport pathways - Water-soluble nutrients and smaller products of fat digestion are absorbed into capillaries; liverLymphatic system transport pathway - Larger fats and fat-soluble vitamins are absorbed into lactealsGastro esophageal Reflux (heartburn) - Occurs when stomach content including acids moves from the stomach into the esophagusGERD - Chronic heartburn; symptoms included burning sensation, pain, bleeding, ulcers, and cancerUlcers - Occurs in the esophagus, stomach, or small intestine from damage to lining by stomach acid andpepsin; causes by H. Pylori, aspirin, and other pain relievers; symptoms include pain, bleeding, and cancerGallstones - Solid material accumulates in the gall bladder and/or bile ducts and blocks bile; symptoms includes painDiarrhea - Frequent, watery stools occur when substances move too quickly through the large intestines for water to be absorbed or when water is drawn from cells into the lumen of the intestines; caused by infections, irritants, medications, and diseases; symptoms include pain, dehydration, and malnutritionConstipation - Hard, dry stools which are difficult to pass; caused by too little water, fiber, exercise, decreased strength of large intestinal muscles,