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University of Alaska Anchorage_BIOL112

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Ch. 12Test 3 Study Guide:Chapter 22 Respiratory System1. Know how CO2 is transported or carried in blood. What percentage is carried as bicarbonate, dissolved in gas, carried on globin? a. Blood transports CO2 from the tissue cells to the lungs in three forms. Dissolved in plasma (7-10%): the smallest amount of CO2 is transported simply dissolved in plasma. Chemically bound to hemoglobin (just over 20%): dissolved CO2 is bound and carried in the RBCs as carbamicohemoglobin. As bicarbonate ions in plasma (about 70%): most carbon dioxide molecules entering the plasma quickly enter RBCs, where the reactions that prepare CO2 for transport as bicarbonate ions in plasma mostly occur. When dissolved CO2 diffuses into RBCs, it combines with water, forming carbonic acid. It is unstable and dissociates into hydrogen ions and bicarbonate ions 2. Where and how do we convert CO2 into bicarbonate? a. Most carbon dioxide molecules entering the plasma quickly enter RBCs, where the reactions that prepare CO2 for transport as bicarbonate ions in plasma mostly occur. When dissolved CO2 diffuses into RBCs, it combines with water, forming carbonic acid. It is unstable and dissociates into hydrogen ions and bicarbonate ions Chapter 23 Digestive1. Know the 6 essential digestive processesa. The 6 essential digestive processes are ingestion, mechanical digestion, chemical digestion, propulsion, absorption, and defecation. Ingestion is taking the food into the digestive tract, usually via the mouth. Propulsion moves food through the alimentary canal (swallowing). Peristalsis is the major means of propulsion- it involves alternating waves of contraction and relaxation of muscles in the organ walls. Mechanical breakdown increases the surface area of ingested food, physically by preparing it for digestion by enzymes. Mechanical processes include chewing, churning food in the stomach, and segmentation (rhythmic local constrictions of the small intestine). Digestion involves a series of catabolic steps in which enzymes secreted into the lumen of the alimentary canal break down complex food molecules to their chemical building blocks. Absorption is the passage of digested end products from the lumen of the GI tract through the mucosal cells by active or passive transport into the blood or lymph. Defecation eliminates indigestible substances from the body via the anus in the form of feces. 2. Know the function of a mesentery. a. A mesentery is a double layer of pericardium. Its functions include it provides routes for blood vessels, lymphatics, and nerves; and is holds organs in place and stores fat. 3. Know the function and content of saliva. a. Salivation is a parasympathetic function. Its functions include: it cleanses the mouth, moistens and dissolves food chemicals, aids in bolus formation, and contains enzymes that begin the breakdown of starch. Saliva is made up of 97-99.5% water, it is hypoosmotic; it is also a slightly acidic solution containing electrolytes, enzymes, and defensins. Saliva protects against microorganisms because it contains IgA antibodies, lysozyme- a bacterial enzyme that inhibits bacterial growth in the mouth and may help prevent tooth decay, and defensins. Solutes include electrolytes (Na+, K+, Cl-, PO43-, 1and HCO3-), digestive enzymes salivary amylase and lingual lipase, the proteins mucin, lysozyme, and IgA, and metabolic wastes. 4. Where do we start digesting starch/carbohydrates? a. We begin to digest starch and carbs in our mouth while chewing. Salivary glands produce enzymes that begin the chemical breakdown of starchy foods. Salivary amylase,present in saliva, splits starch into oligosaccharides, smaller fragments of two to eight linked glucose molecules. Starch digestion continues until amylase is inactivated by stomach acid and broken apart by the stomach’s protein digesting enzymes. 5. What is amylase?a. Amylase is an enzyme that is secreted from salivary glands, pancreatic glands, and glands in the small intestine. They are the main factor in the digestion and breakdown ofstarch and carbohydrates.6. Know the chemicals that influence the secretion of hydrochloric acid (HCl-) into the stomach.a. Parietal cell secretes and produces HCLb. HCL secreting parietal cells is stimulated by three chemicals all of which bind to G protein coupled receptors on the parietal cells membrane and work thorough a second messenger system. The three chemicals are Ach, gastrin, and histamine. When only one of the three chemicals binds to parietal cells, HCL secretion is scanty, but when all three bind, HCL pours forth. 7. What is the role of HCl- in food digestion?a. HCL has a very acidic pH (1.5-3.5) which denatures protein in food, it activates pepsin, and kills many bacteria. 8. Know the cells of the gastric gland: parietal cell, chief cell. What do they produce?a. The parietal cell secretes and produces HCl and the intrinsic factor. The chief cell secretes inactive enzyme pepsinogen which is activated to pepsin. 9. Know the three phases of gastric secretion/salivation (cephalic/gastric/intestinal).a. The cephalic (reflex) phase: lasts only a few minutes prior to food entry. The Gastric phase: last’s 3 to 4 hours after food enters the stomach. The intestinal phase: brief stimulatory effect as partially digested food enters the duodenum, followed by inhibitory effects (enterogastric reflex and enterogastrones). 10. What cell produces HCO3- in the duodenum?a. In the Pancreas there are acini (clusters of secretory cells) the secrete pancreatic juice which contains HCO3-. 11. What is the role of bile in fat digestion?a. Bile is a yellow-green, alkaline solution that contains bile salts, bilirubin, cholesterol, neutral fats, phospholipids, and electrolytes. Bile salts contain cholesterol derivatives that function in fat emulsification and absorption. Bilirubin is a pigment formed from heme. 12. What is the major absorptive organ of the digestive tract?a. Small intestine. 13. Know what organs are retroperitoneal and intra-peritoneal. a. Retroperitoneal organs are organs that adhere to the dorsal abdominal wall and lose their mesentery and come to lie posterior to the peritoneum; these organs include mostof the pancreas, the duodenum, and parts of the large intestine. b. Intra-peritoneal (peritoneal) organs are digestive organs that keep their mesentery and remain in the peritoneal cavity; examples are the stomach. 14. Know what muscles relax and contract during defecation.2a. In the


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