Carbohydrates PDF

carbohydrates  Overview Definition of Carbohydrates. Classification of Carbohydrates. Functions of carbohydrates Regulation of carbohydrates metabolism  Definition of Carbohydrates Carbohydrates are defined as poly hydroxy aldehydes or ketones and their derivatives...

carbohydrates  Overview Definition of Carbohydrates. Classification of Carbohydrates. Functions of carbohydrates Regulation of carbohydrates metabolism  Definition of Carbohydrates Carbohydrates are defined as poly hydroxy aldehydes or ketones and their derivatives or as substances that yields this compounds on hydrolysis A carbohydrate is a biological molecule consisting of carbon (C),hydrogen (H) and oxygen (O) atoms  Classification of Carbohydrates Base on number of sugar units in the chain: Carbohydrates are classified according to the number of sugar units that make them up to Monosaccharaides Disaccharides Oligosaccharides Polysaccharides  Monosaccharaides They are the simplest sugars and cannot be hydrolysed further into smaller units. Contain a single carbon chain Monosaccharaides are classified : 1. Based on number of carbon atoms they possess: Trioses , Tetrose , Pentose Hexoses , 2. Depending upon their groups : as aldoses or ketoses.  Disaccharides Combination of tow monosaccharaides A disaccharide is formed when a dehydration reaction joins two monosaccharaides this covalent bond is called a glycosidic linkage The most common disaccharides are Maltose( Glucose + glucose) Lactose (Glactose + glucose Sucrose (Fructose + glucose) Lactase is the disaccharidase enzyme responsible for hydrolysis of disaccharides to monosaccharaides.  Oligosaccharides Oligosaccharide, any carbohydrate composed from three to ten units of simple sugars (monosaccharaides).  Polysaccharides Most carbohydrates found in nature occur as polysaccharides, polymer of medium to high molecular weight. Polysaccharides, also called glycans, differ from each other in the identity of their recurring monosaccharide units, in the length of their chains, in the types of bonds Iinking the units, and in the degree of branching Amylase hydrolyzes starch to disaccharides Polysacariedes are of two types Homopolysaccharides: contain only a single monomeric species. Heteropolysaccharides contain two or more different kinds of monomeric species.  Chemical properties of carbohydrates Some of carbohydrates are reducing substance can reduce or oxidize other compound. Example ( glucose ,maltose ,Fructose, lactose and glactose). Non reducing carbohydrates can not reduce or oxidize compound example sucrose  Functions of Carbohydrates Energy to fuel cellular reaction. Are intermediates in the formation of fats and proteins. Aid in regulation of nerve tissue and is the energy source of the brain. Formation of RNA and DNA. Formation of connective tissue. The nervous system including the brain totally depends on the glucose from ECF. The nervous tissue cannot concentrate or store glucose.  Fate of Glucose Ingested carbohydrates are polymers such as starch and glycogen. Amylase enzyme is responsible for the digestion of this compound to disaccharides and dextrin. The enzymes sucrase and lactase are hydrolyze sucrose to glucose and fructose and lactose to glucose and glactose. Glucose is absorbed from small intestine, then metabolism of the carbohydrate in the body begins. Glucose is transported through blood stream to the liver. In the liver glucose either used or stored There are three ways in which glucose is either utilized or stored in the body: Glycolysis. ,Glycogenesis' Conversation to fat  Glycolysis Break down of glucose to pyruvic acid or lactic acid (or both) for the production of energy in form (ATP)  Glycogenesis & Glycogenolysis The process of glycogen formation is called glycogenesis. While the term glycogenolysis describes the break down of glycogen Glucose is converted to glycogen and stored in the liver and skeletal muscle  Glucose when needed by the body can be recovered from fat and protein. This process is known as gluconeogenesis  Regulation of Blood Glucose Metabolism This is under two major hormones : insulin and glucagon , both produce by the pancreas their action oppose each other. Other hormones include: Epinephrine Glucocorticoid ACTH Growth hormone. Thyroxine. Somatostatin.  Insulin Primary hormone responsible for the entry of glucose into the cell. Produce and secrete by beta cell in the islets of Langerhans in the pancreas. Normally released when glucose level are high and not It decreased blood glucose level by : Transport glucose to muscle and adipose tissue. Increases glycogenesis, lipogenesis and glycolysis and inhibiting glycogneolysis. Insulin is the only hormone decreased blood glucose levels (hypoglycemic hormone).  Glucagon Primary hormone responsible for increase blood glucose. Produce and secrete by alph cell in the islets of Langerhans in the pancreas. Releasing during stress and fasting states. Act by glycogenolysis in liver increase gluconeogenesis Can refer to as hyper glycemic hormone  Epinephrine : oProduce by adrenal medulla. oIncrease plasma glucose Glucocorticoids primarily cortisol: oReleased from adrenal cortex oStimulated by ACTH oIncrease plasma glucose Growth hormone: Released form anterior pituitary Stimulate by decreased blood glucose level and inhibited by increase blood glucose  Somatostatin oProduce by gamma cell in the islet of Langerhans of the pancreas oIncrease plasma glucose level by inhibition of insulin Hypoglycemia  Hypoglycemia is characterized by blood glucose levels that are less than normal. Exact definition of the glucose level in hypoglycemia is under debate; symptoms of hypoglycemia usually occur when blood glucose has fallen below 50 mg/dl. The warning signs and symptoms of hypoglycemia are all related to the central nervous system.  Classification of Hypoglycemia Two types of hypoglycemia occur, Reactive (postprandial, or after meals) Fasting (postabsorptive). Reactive hypoglycemia It is the hypoglycemia that is caused by a stimulus such as excessive insulin administration Fasting hypoglycemia Hypoglycemia that occurs after fasting is rare. Fasting hypoglycemia may occur as a response to insulinproducing tumors of the pancreas (insulinomas) Reactive hypoglycemia may be diagnosed with Whipple’s triad: low blood glucose with classic symptoms of hypoglycemia, which are improve by glucose administration  Whipple triad Fasting hypoglycemia (