Digestion & Absorption of CHO PDF

Introduction to biochemistry  Definition Science in which chemistry is applied to studying living organisms, and the atoms and molecules comprising living organisms. The chemistry of life. Aim To explain biological form and function in chemical terms. Why is it importa...

Introduction to biochemistry  Definition Science in which chemistry is applied to studying living organisms, and the atoms and molecules comprising living organisms. The chemistry of life. Aim To explain biological form and function in chemical terms. Why is it important? To understand what the cell is doing, we can prevent or treat diseases, and make things happen.  The Foundations of Biochemistry Cellular Foundations Chemical Foundations Physical Foundations Genetic Foundations Evolutionary Foundations Knowledge of biochemistry is essential to all life sciences: Physiology, Immunology, Pharmacology, Pathology, Toxicology, Microbiology  1. Cellular Foundations Diverse living organisms share common chemical features: 1. Basic structural units (cells). 2. Monomeric subunits (nucleotides, amino acids). 3. Pathways for synthesis of cellular components. 4. Genetic code and history of evolutionary change from same ancestors.  All living cells share certain structural features  2. Chemical foundations Biochemistry aims to explain biological form and function in chemical terms. All organisms share a common evolutionary origin based on the observed universality of chemical intermediates & transformations “biochemical unity” Jacques Monod (1954): “What is true of E. coli is true of the elephant.” Macromolecules Three families of macromolecules  Digestion & absorption of carbohydrates  Introduction Dietary Carbohydrates Monosaccharides Disaccharides Polysaccharides a) Glucose (Grape Sugar) a)Maltose (Malt Sugar) a) Starch b) Fructose (Fruit Sugar) b) Lactose (Milk Sugar) b) Cellulose c) Sucrose (Cane sugar) c) Glycogen c)Galactose (brain sugar) Cellulose Q Not digested by human digestive system ?  Introduction Digestion & Absorption 1- In the Mouth: Salivary amylase acts on the α 1-4 glucosidic bonds 2- In the Stomach Some acid hydrolysis 3- In the Small Intestine a) Pancreatic amylase b) Intestinal disaccharidases  Introduction Digestion & Absorption glucose, galactose and fructose  Introduction Digestion & Absorption Absorption Simple Facilitated Cotransport (Passive) Transport (Active Transport) Diffusion (GLUT-5)  Introduction Digestion & Absorption Q Transporters Transport of glucose and galactose by SGLT-1 is an active transport Glucose-Na+ symport glc-Na+ symport protein  Disorders of Digestion & Absorption 1- Lactose intolerance (Lactase deficiency) - Cause: Deficiency of Lactase E. - Manifestations: Vomiting, Bloating, Watery Diarrhea, Cramps & Dehydration - Treatment: Avoid lactose-containing diet  Disorders of Digestion & Absorption 2- Sucrose intolerance (Sucrase deficiency) - Cause: inherited sucrase deficiency - Manifestations: Similar to lactase deficiency. It starts later after addition of cane sugar (sucrose) to the infant's diet - Treatment: Avoid Sucrose containing diet  Introduction Uptake of Glucose - Glucose is transported through cell membranes of different tissues by different protein carriers or Transporters - Facilitative transporters and Sodium dependent transporters  Introduction Uptake of Glucose GLUT- 2 - Is important for regulation of blood glucose - Is for rapid uptake and release of glucose - Liver & Kidney Glucose Homeostasis - Pancreatic B-cells Insulin Secretion - Basal Border Absorption of sugars Small Intestinal  Introduction Uptake of Glucose GLUT- 4 - Is Insulin dependent transporter  Introduction Uptake of Glucose GLUT- 4 - Is Insulin dependent transporter Heart Skeletal muscles Adipose Tissue - Ensure that, glucose uptake by these tissues only when the blood glucose is increased Q Transporters - GLUT- 2 Is important for regulation of blood glucose. - Glucose transporter in heart, skeletal muscles & adipose tissue is of GLUT-4 type.  Introduction Fate of Absorbed Sugars Glucose Provides Oxidation Other Storage Compounds CHO, Lipid Glycogen & A.A TAG Glucose can be excreted in urine if its plasma level exceeded the renal threshold (180 mg/dl)   OXIDATION OF GLUCOSE Major pathway Minor pathway Glycolysis Uronic acid HMP Krebs’ cycle pathway ETC  MCQ - Glucose transporter in myocyte stimulated by insulin is: A. GLUT-1 B. GLUT-2 C. GLUT-3 D. GLUT-4  MCQ - Facilitated transport of glucose that is insulin insensitive (non - dependent) takes place in: A. Skeletal muscle B. Liver C. Adipose tissue D. Heart