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UAB BY 124 - In stomach

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BY 124 1st Edition Lecture 15Outline of Last Lecture Chapter 41I. Essential CompoundsII. Enzymatic HydrolysisIII. GroupsIV. How animals feed V. The appearance of an alimentary canalVI. Processing stagesVII. What is food?VIII. In mouthIX. Crucial diagram for studyingOutline of Current Lecture Chapter 41 (cont.)I. In stomachII. Hormones III. Small intestineIV. Other organs used in digestiona. Liver b. Gall bladderc. Biled. Pancrease. Cecumf. Large intestineV. Nutrition Current LectureChapter 41 (cont.)I. In stomacha. Lots of gastric pits (Figure 41.11)i. Mucous cells – mucusii. Parietal cells – hydrochloric acid (HCl)iii. Chief cells – pepsinogen (can be changed to pepsin by HCl given off by parietal cells)II. Hormone – to excite or set in motiona. Zymogens – inactive enzymesb. Gastrin – produced by lower part of stomach. Gets in blood and the moves into top of stomachi. Helps release of pepsinii. Controlled by nervous system and other hormonal releasec. Pepsin – reduces proteins to small polypeptidesd. HCl – not necessarily a hormone; breaks things down because very acidic. i. Breaks down “glue” between cells which is important because it increases surface areaii. Antimicrobial agent for stomachiii. Thought to have caused ulcers1. Found that ulcers were actually caused by Helicobacter pylorie. Bolus is turned into chimef. Chyme leaves pyloric sphincterg. Have fast growing cells – why it is hard for those on chemotherapy to eatIII. Small Intestine (Figure 41.9)a. Small and large intestinesi. Small intestine has smaller diameter than large intestineb. Figure 41.17i. Carnivore – longer small intestine, short cecum, and shorter large intestineii. Herbivore – shorter small intestine, long cecum, and longer large intestinec. 3 parts:i. Duodenum1. Where most digestion occursii. Jejunumiii. Ileum 1. Where most of absorption of nutrients occurs – microvillia. “brush border”b. Inside villi (Figure 41.13)i. Blood capillary – goes into blood1. Amino acids and glucoseii. Lacteal – goes into lymph vessels (lymphatic system)1. Fat iii. Uses active diffusion by using pumps iv. Fat moves into epithelial cells and they are formed into triglycerides where they are coated with phospholipids, cholesterol, and proteins to create a chylomicron which passes into lactealsd. Breaks down nucleic acids coming from pancreas by breaking phosphodiester bond and turning them into nucleotidesIV. Other organs used in digestion (Figure 41.9)a. Liver – i. Constantly makes and secretes bile that is stored and released through the gall bladder and contains the breakdown products of hemoglobinii. Adds color to fecesb. Gallbladder – i. Does not make anythingii. JUST stores and releases bileiii. Releases bile when cholecystokinin (CCK) is triggered by food entering intestines1. CCK also effects pancreasc. Bile (not an organ)i. Does not digest anything1. Emulsification – breaks up into smaller pieces (kind of like shaking a ball of oil in water and seeing it split up)a. Increases surface area ii. Alkalined. Pancreas – (Figure 41.19)i. Pancreatic ii. Secretes digestion enzymesiii. Helps neutralize chyme by producing sodium bicarbonate1. Results in “basic” environmentiv. Releases secretin – secretin tells pancreas to release sodium bicarbonatev. CCK is told to release its enzymes here toovi. Enterogasterones1. CCK and secretin2. Tells stomach to slowly release chymevii. 3 zymogens released by pancreas in response to CCK (in lumen of duodenum)1. Trypsinogen → releases trypsin which can react to make more trypsin or/and it can activate the next two zymogens2. Procarboxypeptidase3. Chymotrypsinogenviii. Endopeptidase and exopeptidase 1. Pepsin, trypsin, and chymotrypsin → endopeptidasesa. Break bonds in middle of polypeptide chainb. Some can be very specific 2. Aminopeptidase and carboxypeptidase → exopeptidasesa. Cut from the endb. Aminopeptidase – cuts one amino acid in on amino endc. Carboxypeptidase – cuts one amino acid in on carboxyl ende. Cecum – i. Junction between small and large intestineii. Appendix located just below it1. Thought to be a vestigial organiii. Cows use it to store microorganisms to help breakdown cellulose in the plants that they eatf. Large intestinei. 2 parts1. Colona. Ascendingb. Transcendingc. Descending2. Rectuma. Ends with the anusii. Basically does the final check on wateriii. Gets rid of saltsiv. Escherichia Coli (E. Coli)v. Rectum will get filled and will send a signal to brain to release the buildup of fecal material vi. Material can spend anywhere from 12-24 hours in the large intestineV. Nutritiona. Essential amino acids for adults (Figure 41.2)i. Methionineii. Valineiii. Threonineiv. Phenylalaninev. Leucinevi. Isoleucinevii. Tryptophanviii. Lysineb. “Essential” means that your body cannot make them and that you have to get them in your dietc. Basal metabolic rate – amount of energy measuredin calories needed to maintain your body at restd. Fats give (~1.5x) more energy than protein and carbohydratese. Table 41.1 – vitamin requirements of humansi. Only have to know which are fat and water solublef. Table 41.2 – mineral requirements of humansi. Trace minerals – only need a little bit of


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