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Review for Module 7 quiz 1. What is an enzyme and how does it work? What is the active site of an enzyme? What major nutrient form enzymes? - An enzyme is a protein with a specific shape that lowers the Energy of activation. The specific site to which the substrate attaches is known as the active site. The enzyme and substrate join much like a ‘lock and key’ - It’s a Protien 2. Describe 3 ways enzymes are ‘turned off’ or their activity is slowed down. - Temperature – anything away from optimum may cause denaturation or coagulation - pH - substrate concentration – once saturation is reached reaction levels off - Review: The effect of temperature and ph of enzyme activity and what the purpose of an enzyme is: 3. Define monomers and polymers- A monomer is the simplest unit a polymer is made up of numerous monomers Eg. Starch is a polymer made of many glucose molecules 4. What is a lipid? Carbohydrate? Protein? What are their functions in the body? Also give examples Lipid – made of a glycerol backbone and 3 fatty acids and is known as a triglyceride, functions as a part of cell membranes, some hormones, insulation, and energy source Carbohydrate (CH2O) – part of cell membranes and is our major Energy source Protein – made up of amino acids (which contain N),of which there are 20 – 8 are essential and must be obtained from the diet, functions as part of cell membranes, enzymes, muscle tissue and energy source 5. Define, differentiate, give examples, and uses of monosaccharide, disaccharides, and polysaccharides. Monosaccharides – glucose, fructose and galactose – glucose major Energy source in blood Disaccharides – sucrose, lactose, and maltose – lactose is milk sugar Polysaccharides – starch (stored form in plants),glycogen (stored form in animals) and cellulose (structural carb in plants – fiber) Know the structure of a lipid (What things make it up) -All triglycerides (Lipids) have a glycerol backbone (that is always the same) and 3 fatty acids attached. The fatty acids are what differ among different types of triglycerides. Know the structure of a protein (What things make it up) - Proteins are formed from long chains of amino acids that are joined together by peptide bonds. - - The Enzyme Pepsin breaks proteins up into its amino acids 6. Give all the monomers of the three nutrients. Carbohydrates – monosaccharides / Protein – amino acids / Lipids - triglycerides 7. Describe lab tests that are used to identify all three nutrients. Benedicts – reducing sugar test – blue solutions turns orange upon heating Biuret test – protein test – blue solution turns purple in presence of peptide bonds Iodine test – yellow iodine turns black/blue in presence of starches Brown paper turns translucent in the presence of fats Benedicts test: Biuret test: 8. Define and differentiate between physical and chemical digestion Physical – break into smaller pieces to increase surface are Chemical – break bonds to break food into monomers for absorption 9. Trace the path of a piece of food from the time it enters the mouth until the waste leaves the body. Give key features of each organ Mouth – chewing – physical digestion/ saliva begins carb. digestion Pharynx – throat links esophagus and trachea Epiglottis – prevents food from entering trachea when swallowing Esophagus – peristalsis pushes bolus towards stomach Cardiac (esophageal) sphincter – controls the rate of food entering stomach Stomach – physical digestion using HCl, chemical digestion of proteins Pyloric sphincter – control rate of chyme entering duodenum Duodenum – first part of the small intestine where most digestion occurs Ileum – last part of the small intestine where most absorption occurs Large intestine – absorption of water, and electrolytes and formation of digestive wastes in the form of feces. Be able to Identify all the different parts of the digestive system: Know generally the role of each part of the digestive systems in food digestion (the following picture might help). (Accessory organs: Liver, Pancreas and Gall Bladder) Know the following Accessory organs and there role in Digestion: Accessory organs: 1) Pancreas - a soft tubular gland that lies just behind the stomach, and is connected to the duodenum by two ducts - has both a exocrine (secretory) and endocrine (hormonal) function - its exocrine functions are to secrete digestive enzymes and sodium bicarbonate to neutralize the stomach acid and establish a pH of 7.1-8.2 which will not only neutralize the enzyme pepsin, but activate the pancreatic enzymes - enzymes: - pancreatic amylase – digest carbohydrates maltose - trypsin – protein digestion: peptones small polypeptides (activated by enterokinase, secreted by the intestinal wall) - chymotrypsin – protein digestion: small polypeptides peptides (activated by trypsin) - carboxypeptidase – digests polypeptides amino acids - lipase – digests fats into fatty acids and glycerol - ribonuclease – digests RNA to nucleotides - deoxyribonuclease – digests DNA to nucleotides 2) Liver - the liver has over 500 functions, three being fundamental: - production of bile - storage of glucose in the form of glycogen ( fat if glycogen limits exceeded), conversion of galactose and fructose to glucose - detoxification of the blood (makes enzymes to break down toxins; ex: alcohol, caffeine, nicotine, barbiturates, poisons, excess hormones) - deamination of amino acids – removing nitrogen, producing ammonia and eventually urea (excreted by the kidneys) - it receives two separate blood supplies - via the portal vein – bringing freshly absorbed nutrients from the small intestine - via the hepatic artery – bringing oxygenated blood from the lungs/heart - bile - each day, the liver secretes between 800 – 1000 mL of bile - bile is stored in the gallbladder for release on demand into the small intestine - consists of water, bile salts, cholesterol and bile pigments (made from bilirubin – yellow in colour) - bile acts as an emulsifier, breaking large fat globules into small ones, allowing lipase more surface area for digestion Know the following organs and there role in Digestion: Mouth - the mouth is where mechanical and chemical digestion begins - the food is moistened by saliva produced by the salivary glands(we produce 1.7 L per day), which moistens the food to make it easier to swallow, and also contains the first digestive enzymes: - amylase (enzyme names end in ase) which begins the breakdown of starch into maltose (a disaccharide) and dextrins (short glucose chains), and maltase, which breaks maltose into glucose Stomach - the stomach holds up to 2L (4L) of food, and will hold food for from 3 to 6 hours while it is broken down - There are three important chemicals in the stomach involved in digestion: - HCl(aq) – secreted by the parietal cells of the stomach, lowers the pH of the stomach to 2.0, allowing the activation of pepsin to pepsinogen - Pepsin – secreted as an inactive precursor, pepsinogen (cannot be active or it would digest cellular proteins) by the peptic (chief) cells. It is activated by the lowered pH in the stomach (which changes the shape of the enzyme) - mucous – secreted by the mucous (goblet) cells, protects the stomach endothelium from the acid and enzymes - Two other secretions: - gastrin – a hormone that stimulates gastric secretions (which is stimulated by the presence of proteins in the stomach), and relaxes the pyloric sphincter to allow stomach emptying - rennin – found principally in children, it is involved in the digestion of milk – slowing its emptying from the stomach - physical digestion - the acid along with the peristaltic motions of the stomach contents helps to break up tissues - the pepsin will break up proteins into smaller polypeptides called peptones (protein digestion will be completed in the small intestine) - most materials are not absorbed in the stomach, but some drugs (notably aspirin), some water, electrolytes, alcohol and some are absorbed in the stomach - the highly acidic stomach contents, called chyme is emptied into the small intestine a bit at a time through the pyloric sphincter Small Intestine - measures up to 7m in length, but only 2.5 cm in diameter, divided into three sections - duodenum – 25 cm long, where most digestion occurs - jejunum – 3 m long focusing on absorption - ileum – 4 m long - the majority of digestion and absorption (90%) takes place here – lipid digestion, continuation of carbohydrate and protein digestion - the accessory organs of digestion, the pancreas, gall bladder and the liver secrete their juices into the duodenum to aid in digestion - the small intestine, in order to better digest and absorb digested materials is highly folded to increase surface area (by 600x); the folds are called villi, which are covered in small cytoplasmic projections called microvilli, the structure of the small intestine (from the outer surface in) includes: - villi/microvilli – surface (epithelial) cells designed for absorption - lacteal – vessel projection of the lymphatic system, designed to absorb fats - capillaries – vessels of the circulatory system, for absorption of all other nutrients for immediate transport to the liver for processing - as the chyme enters the duodenum, its acidity and contents stimulates a number of hormones’ release, which in turn stimulate the secretion of digestive and protective chemicals from accessory organs and the intestinal epthelium itself Large Intestine - about 1.5 m in length, a diameter of 6.5 cm. - at the junction of the small and large intestine, the ileum exists the appendix, which has no real function given our diet - the large intestine has three main functions: - absorption of water and electrolytes - production of feces – consisting of water, inorganic salts, cells from the GI tract, bacteria, bacterial decomposition and undigested food - housing bacteria, that will use remaining unabsorbed nutrients or undigested carbohydrates to make vitamin K and B vitamins for us to absorb (as well as methane gas) 10. Why are salivary glands important? Moistens food forming the bolus and contains salivary amylase starting carbohydrate digestion 11. Identify all of the enzymes found in the stomach. What do they digest? How are these enzymes activated? What does the mucous lining do? Pepsinogen activated by HCl forms pepsin which breaks proteins down into polypeptides. Mucous lining prevents the stomach walls form being digested. 12. Identify all of the enzymes found in the small intestine. What do they digest? What do they produce? How are they activated? - Pancreatic amylase breaks down carbs - Carbohydrases break down disaccharides into monosaccharides - Pancreatic proteases (trypsin) breaks down polypeptides into dipeptides - Pancreatic lipase breaks down fats into fatty acids - These enzymes are all activated by the secretion of bicarbonate from the pancreas - result in a pH of 8 13. Discuss the role of the pancreas in digestion. Why doesn’t the pancreas digest itself? What is the role of bicarbonate ions? - Pancreas secretes various digestive enzymes - Enzymes are secreted in inactive form - Bicarbonate reduces acidity of the duodenum activating enzymes. 14. Discuss the role of the liver and gall bladder in digestion. - Liver produces bile which is stored in the gall bladder – physically breaks down fats by emulsification 15. How is the surface area of the small intestine increased? Why is this important? - The lining of the gut is folded into villi and microvilli greatly increasing SA – allows us to absorb large quantities of nutrients 16. What is peristalsis? Identify two places it occurs. - Rhythmic contraction of smooth muscle – esophagus and small intestine 17. Why is chewing important in digestion? Increases surface area of food molecules making digestion more efficient 18. How and where are all the monomers of lipids, proteins, and carbohydrates absorbed? What happens to the nutrients after they are absorbed? - Amino acids and monosaccharides are absorbed from the villi into blood - Fatty acids absorbed from villi into lymph (lacteal) - Once absorbed these nutrients are used for life processes 19. Why is the diet of a person whose gall bladder has been removed restricted in fat intake? - Less bile 20. What is the role of the large intestine? Absorption of water, electrolytes and elimination of digestive waste in the form of feces. 21. What does the epiglottis do? Prevents liquids/solids from entering the trachea Respiration, Ch 7 1. Describe the path of a molecule of oxygen as it moves from the air to a blood cell. Give key features of each part of this respiratory tract Nose – warms and moistens air Pharynx – hallway between digestive and respiratory systems Trachea – mucus traps debris and cilia sweep it away - has cartilage rings to prevent collapse Bronchi – one leading to each lung, mucus and cilia – trap and sweep and divide Bronchioles – smaller tubes throughout the lungs leading to Alveoli – microscopic air sacs where oxygen diffuses to blood 2. What does the nasal cavity do to the air that is inhaled? Moisten and warms the air 3. How do bronchioles differ from the trachea? They are smaller and do NOT have cartilage rings 4. Where does gas exchange with blood occur in the respiratory tract? Why does it occur in this location? The alveoli walls are very thin and are surrounded by capillaries •Carbon dioxide and oxygen transfer between the alveoli and capillaries through diffusion •You have about 150 million alveoli, whose total combined surface area could cover a tennis court! Between the blood capillaries and the alveoli – this location has a large surface area, is moist, and the walls are thin enough to allow diffusion 5. Why must the internal surface of the lungs be kept moist? Facilitates diffusion 6. Why are there tiny hairs (cilia) and mucus in the respiratory tract? Trap and sweep debris 7. What is the role of the cartilage rings (C-rings) that line the trachea and bronchi? Prevent collapse of these tubes 8. Describe the movement of your ribs, intercostal muscles and diaphragm as you breathe in and out. Inhalation – active process – diaphragm moves down and ribs up and out lowering air pressure Exhalation – passive process – diaphragm moves up and ribs drop back down raising air pressure 9. Explain why a pressure gradient must be made to allow proper inhaling and exhaling Air always moves from high pressure to low pressure 10. Define the following terms: tidal volume, inspiratory reserve volume, expiratory reserve volume, vital capacity. What device takes these measurements? Spirometer readings: 11. Why must the respiratory system and the circulatory system work together? Oxygen gained through respiration and delivered via circulation 12. List and describe 3 respiratory disorders. Pneumonia, Emphysema, Lung Cancer 13. Describe the structure and function of hemoglobin. What blood cell contains hemoglobin? Explain how hemoglobin picks up oxygen Hb contains 4 Heme (Fe2+) which binds to oxygen and the globin part binds to carbon dioxide 14. How is carbon dioxide transported in the blood? What is carbonic anhydrase needed for in the blood? - HbCO2 - Dissolved in the blood plasma - H20 + CO2 forms H2CO3 which dissociates into H+ and HCO3 - Transport of Gases in the Blood - •oxygen is only slightly soluble in the blood (0.3mL / 100 mL), so it must be bound to hemoglobin to be transported in the blood. As oxyhemoglobin, the blood can carry 20 mL/100 mL of oxygen. The amount of oxygen that combines with hemoglobin depends on the partial pressures of oxygen in the blood and in the tissues. About 97% of all oxygen is carried by oxyhemoglobin, and the other 3% is carried in the plasma of the blood. - •About 9% of the carbon dioxide is carried in the plasma and 27% is carried as carbaminohemoglobin (HbCO2), and 64% is carried as carbonic acid or bicarbonate. This reaction is catalyzed by the enzyme carbonic anhydrase. The reaction decreases the amount of carbon dioxide in the plasma, thus increasing the rate of diffusion of carbon dioxide from the cells to the blood. Once the blood is returned back to the lungs, the concentration of carbonic acid becomes very high, encouraging the diffusion of carbon dioxide out of the blood into the lungs. 15. If the blood has lots of carbon dioxide in it, what would its pH be? Explain Acid due to the build – up of H+ ions 16. What are chemoreceptors? How do they control breathing rate? Measure pH and regulate breathing •Breathing is an autonomic function that is controlled by nerves from the medulla oblongata in the brain. Chemoreceptors detect the levels of carbon dioxide (acid) and oxygen in the blood and signal the brain to speed up or slow down breathing. 17. Describe all the ways smoking destroys your respiratory tract. - Damages cilia - Damages mucus producing cells - Destroys lung tissue