Energy, Chemical Reactions and Enzymes

Transcription

1 Phosphorylation Hydrolysis Energy, Chemical Reactions and Enzymes Chapter 2 (selections) What is Energy? Energy is the capacity to do work Potential Energy Kinetic Energy Chemical Bond Energy Like a rechargeable battery ATP Energy from exergonic reactions Energy for endergonic reactions ADP + P

2 Laws of Energy Laws of Energy Laws of Thermodynamics: First Law Laws of Thermodynamics: Second Law Chemical Reactions Exergonic Reactions vs. Endergonic Reactions Reactants Products Energy of Activation

3 Enzymes Enzymes are proteins that serves as a biological catalysts, increasing the rate of reactions without being consumed in the reactions. Alkaline phosphatase Energy Reactants Progress of the reaction E A without enzyme Products E A with enzyme Net change in energy Enzymes Substrate Active site Cofactors and coenzymes The lock and key hypothesis states that the active site specifically matches the shape of the substrate enzyme active site

4 Enzymes can be Inhibited or Enhanced Competitive Inhibitors Noncompetitive (allosteric) Inhibitors or Stimulators Everything competes for the active site! Competitive Inhibition Non-competitive (allosteric) Inhibition and activation

5 Functions and Processes of the Digestive System: Move nutrients, water, electrolytes from external to internal environment Protective function Digestive Homeostasis Requires: 1. Digestion: chemical, mechanical breakdown of food polymers! monomers 2. Absorption From GI lumen to ECF Not regulated; "what you eat is what you get." Digestive Homeostasis Requires: 3. Motility Ingestion, mastication, peristalsis, segmentation Regulated 4. Secretion Exocrine and endocrine (hormones, enzymes, mucus, paracrines) Regulated Many enzymes are secreted as inactive proenzymes known as zymogens The Challenges: Prevent autodigestion Match input with output

6 Layers of the GI Tract 1. Mucosa Absorbs & secretes; contains goblet cells 2. Submucosa Vessels, lymphatics and nerves 3. Muscularis Responsible for movement 4. Serosa Binds and protects Journey Through the Tube: The Esophagus Pharynx to stomach Lower esophageal sphincter Should there be an S in the LES? Open, cut esophagus from a pig

7 Stores food, begins protein digestion, churns bolus and forms chyme Four regions of the stomach Pyloric sphincter Stomach Stomach Rugae and gastric pits Gastric glands: Goblet cells --> mucus Parietal cells --> HCl and intrinsic factor Chief cells --> pepsinogen (a zymogen)

8 Stomach Small Intestine what is the function of such low ph? how is pepsin made? is anything absorbed here? wait a second... what is the stomach made of? Duodenum, jejunum, ileum Absorption of carbohydrates, amino acids, lipids, electrolytes, bile, vitamins, water Why so many villi and microvilli? pepsin Small Intestine Enzymes: Lactase, sucrase, maltase Peptidase Lipase Motility in the small intestine peristalsis segmentation fetal pig

9 Large Intestine Cecum, colon, rectum, anal canal Colon: ascending, transverse, descending, sigmoid Absorbs water and electrolytes Passes waste out of the body how much? how often?

10 Accessory Organs Mouth, cheeks, lips, tongue, palate, teeth Salivary Glands Produce mucus to lubricate food Salivary amylase The Liver

11 Functions of the Liver Functions of the Liver Bile production and secretion Detoxification of blood Carbohydrate Metabolism Glucose! glycogen Glucose! fat Glycogen! glucose Amino acids! glucose 4. Lipid Metabolism Synthesis of triglycerides and cholesterol Excretion of cholesterol 5. Protein Synthesis Gallbladder Pancreas Endocrine functions: Islets of Langerhans Exocrine functions Enzymes produced in the pancreas are produced as zymogens

12 Pancreas Trypsinogen + enterokinase! trypsin Pancreatic juice: water, bicarbonate, amylase, trypsin, chymotrypsin, carboxypeptidase, lipase, nucleases So What? Digestive System Disorders Eating disorders Ulcers Vomiting Constipation, Diarrhea Lactose intolerance Cancers of the digestive system