BIOH 370 1st EditionLecture 24Outline of Last Lecture Digestive System Day 2I. The Stomacha. Gastric Juicesb. HCL in the StomachII. The PancreasIII. Liver and Gallbladdera. Filteringb. Functionsc. Regulation of Bile/ Pancreatic JuicesIV. Small IntestineV. Gut Associated Lymphoid TissueVI. Antigen Recognition and uptake in the GALTVII. Benefits of ProbioticsOutline of Current Lecture Digestive System Lecture Day 3I. Large IntestineII. Phases of Digestion1. Cephalic PhaseThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.2. Gastric Phase3. Intestinal PhaseIII. Digestion1. Carbohydrate Digestion2. Protein Digestion3. Lipid DigestionIV. HormonesV. DefecationVI. Digestive System Developmental AspectsVII. ObesityVIII. Roux en Y Gastric Bypass (RYGB)IX. Metabolism and NutritionX. Metabolism During Absorptive State and Post-absorptive StateXI. ATP- Anabolic and Catabolic ReactionsXII. Oxidation-Reductions (redox) ReactionsXIII. Carbohydrate MetabolismXIV. ChemiosmosisXV. Glucose Anabolism and CatabolismXVI. Lipid Metabolism- Lipid Anabolism and CatabolismXVII. Protein MetabolismXVIII. VitaminsXIX. Key Molecules at Metabolic CrossroadsXX. NutritionXXI. Heat and Energy BalanceXXII. Regulation of Body Temperature XXIII. Heat StrokeXXIV. FeverXXV. Homeostatic ImbalancesCurrent LectureDigestive System Lecture Day 3I. Large Intestine- Functions1. Haustral churning, peristalsis, and mass peristalsis drive contents of colon into rectum2. Bacteria convert proteins to amino acids, break down aa and produce some B vitamins and Vitamin K3. Absorption of wome water, ions and vitamins4. Form feces5. Defecation- Intestinal glands are present in the large intestine are primarily for water absorptionII. Phases of Digestion1. Cephalic Phase: : smell, sight, thought or initial taste of food activates cerebral cortex, hypothalamus and brain stem2. Gastric Phase:- Neural regulation - Hormonal regulation3. Intestinal PhaseIII. Digestion1. Carbohydrate Digestion:- Begins in the Mouth: Salivary and pancreatic amylase begins to hydrolyze polysaccharides in the mouth (and to a limited extent in the stomach) into oligosaccharideso sucrose, maltose and lactose - Small Intestine: Pancreatic amylase which enters the duodenum also hydrolyzes polysaccharides into oligosaccharides Carbohydrate absorption begins in the duodenum and is usually completed by the first 100cm of small intestine2. Protein Digestion:- Begins in the Stomach: Food bolus enters the mouth (stimulates acid production from gastric pareital cells) HCl (and Acetylcholine) stimulates pepsinogen release from chief cells Pepsinogen ®pepsin Presence of food in the antrum, antral distention and vagal stimulation gastrin (in the duodenum) Peptides and aminoacids enter duodenum ®cholecystokinin (CCK)by epithelial cells Pancreatic juice: trypsin, chymotrypsin, carboxypeptidase and elastase- Small Intestine:o Brush border peptidases digest oligopeptides that are absorbed at the luminal border of the enterocyteAminopeptidase and dipeptidaseo 50% of protein absorption occurs in the duodenum but continues through the small intestine3. Lipid Digestion- Stomach:o Lingual lipaseo Gastric lipase- Small Intestine:o When lipids enter the duodenum, cells within the duodenal mucosa secrete CCK and secretin.o CCK + secretin Þ* gallbladder contraction and pancreatic secretiono Pancreas secretes lipase, cholesterol esterase and phospholipase A2 Þ to breakdown the lipidso Bile salts emulsify the lipid byproducts to form micelleso Enterocytes absorb the micelles ®® thoracic duct to enter the blood stream through the left subclavian vein.o Fat absorption occurs along the entire small intestineIV. HormonesV. Defecation:1. Rectum- rectal valves stop feces from being passed with gas2. Anal canal- The last segment of the large intestine3. Sphincters- Internal anal sphincter—smooth muscle- External anal sphincter—skeletal muscleVI. Digestive System Developmental Aspects:1. In the third week - Endoderm has folded and foregut and hindgut have formed- Midgut is open and continuous with the yolk sac- Mouth and anal openings are nearly formed2. In the eighth week- Accessory organs are budding from endoderm3. Fetal nutrition is via the placenta, but the GI tract is stimulated to mature by amniotic fluid swallowed in utero4. The newborn’s rooting reflex helps the infant find the nipple; the sucking reflex aids in swallowing5. Aging results in:- Decreased secretory mechanisms and motility- Loss of strength and tone of digestive muscular tissue- Changes in neurosecretory feedback- Diminished response to pain and internal sensations VII. Obesity:- BMI > 25 is overweighto Over 1.5 billion adults- BMI>30 is obeseo Over 600 million adults- Overweight/Obeseo 61.6% of Montana adults63% of USo 25.6% Montana children31.6% of US- Traditional weightloss strategies involve:o Low energy dietso Exerciseo Behavior therapyo Pharmacotherapy- Bariatric surgeryo Considerable and long term weight lossVIII. Roux en Y Gastric Bypass (RYGB):- Safest and has the most efficacy- Comprises 70-75% of all bariatric surgeries- Can be performed open or laparoscopically (preferred)- Has both malabsorptive and restrictive components- The distal stomach, duodenum and proximal jejunum are bypassed and a small gastric pouch is formedIX. Metabolism and Nutrition:- major nutrients are carbohydrates, lipids, and proteins- Micro nutrients are vitamins and minerals- Water- KCal= amount of energy required to raise the temp 1g water by 1 degree C- For nutritional purposes ‘calories’ refers to KCal.X. Metabolism During Absorptive State and Post-absorptive State:XI. ATP- Anabolic and Catabolic ReactionsATP Generation in animal cells:1. Substrate-level phosphorylation (in cytosol)2. Oxidative phosphorylation (electron transport chain in inner mitochondria membrane)XII. Oxidation-Reductions (redox) Reactions:1. Oxidation; gain of oxygen or loss of hydrogen2. Oxidation-reduction (redox) reactions- Oxidized substances lose electrons and energy- Reduced substances gain electrons and energy3. Coenzymes act as hydrogen (or electron) acceptors- Nicotinamide adenine dinucleotide (NAD+) - Flavin adenine dinucleotide (FAD)XIII. Carbohydrate Metabolism:- What happens to the pyruvic acid depends on the availability of oxygen. - If oxygen is scarce (anaerobic conditions), pyruvic acid is reduced