. More than 60% of our foods are carbohydrates. Starch, glycogen, sucrose, lactose and cellulose are the chief carbohydrates in our food. Before intestinal absorption, they are hydrolysed to hexose sugars (glucose, galactose and fructose).
B. A family of a glycosidases that degrade carbohydrate into their monohexose components catalyzes hydrolysis of glycocidic bonds. These enzymes are usually specific to the type of bond to be broken.
Carbohydrates are digested in the mouth by salivary amylase and in the small intestine by pancreatic amylase and intestinal enzymes. Monosaccharides like glucose are absorbed into the bloodstream through active transport involving sodium-glucose transporters in the intestinal walls. Glucose is the primary fuel for cells and its uptake is mediated by glucose transporters, especially GLUT2 and GLUT4 which are regulated by insulin. Deficiencies in disaccharide-digesting enzymes can cause issues like lactose intolerance and related symptoms.
Digestion & absorption of carbohydratesakina hasan
This document summarizes the digestion and absorption of carbohydrates. It begins by outlining the types of carbohydrates present in the diet and how they are broken down by enzymes into simpler monosaccharides. It then details the specific enzymes involved in digesting carbohydrates at each step, from salivary amylase in the mouth to pancreatic amylase and disaccharidases in the small intestine. Absorption of monosaccharides like glucose, galactose and fructose occurs via active transport in the intestinal epithelium. Clinical examples like lactose intolerance are also discussed.
Digestion and absorption of carbohydrateHerat Soni
This document summarizes the digestion and absorption of carbohydrates. It states that carbohydrates in the diet are primarily complex polysaccharides that are broken down by enzymes into monosaccharides in the gastrointestinal tract. The breakdown process begins in the mouth with salivary amylase and continues in the pancreas with pancreatic amylase and in the small intestine with enzymes that break down disaccharides into monosaccharides. Only monosaccharides can be absorbed into the intestinal cells, primarily through co-transport with sodium ions. The monosaccharides are then released into the bloodstream through facilitated diffusion transporters.
1. Digestion breaks down carbohydrates into monosaccharides like glucose and fructose. Salivary amylase and enzymes in the small intestine like maltase, lactase, and sucrase aid in this process.
2. Monosaccharides are absorbed into the bloodstream via active transport against concentration gradients or facilitated diffusion. Glucose is transported to tissues like the liver and brain, while pentoses are excreted by the kidneys.
3. Lactose intolerance occurs when lactase enzyme is deficient, causing undigested lactose to pass to the colon and cause gas, bloating, and diarrhea.
This document summarizes carbohydrate digestion in the human gastrointestinal tract. It describes how carbohydrates are broken down into smaller molecules by salivary and pancreatic amylases and intestinal disaccharidases and oligosaccharidases. The monosaccharides glucose, fructose and galactose that are produced are then absorbed into the bloodstream in the small intestine. Glucose absorption is an active process that utilizes sodium-glucose co-transporters, while fructose absorption occurs via facilitated diffusion. Factors that can influence carbohydrate absorption such as intestinal health, hormones and vitamins are also discussed.
This document summarizes carbohydrate metabolism, including the absorption of monosaccharides, fate of absorbed sugars, pathways for glucose utilization, oxidation of glucose through glycolysis and the Krebs cycle, and glycogen metabolism. Key points include: monosaccharides are absorbed via simple diffusion, facilitated transport, or active transport; glucose is utilized through oxidation, storage, or conversion to other compounds; glycolysis occurs via two phases to generate ATP or lactate; the Krebs cycle further oxidizes pyruvate to generate more ATP; glycogen is synthesized from and broken down back to glucose to provide energy.
The document summarizes the process of carbohydrate digestion in humans. It begins with mechanical digestion in the mouth through chewing. Chemical digestion then starts with salivary amylase breaking down some starch in the mouth. In the stomach, further mixing occurs and ptyalin continues breaking down starch, with around 30-40% being digested. The acidic stomach stops further digestion. In the small intestine, pancreatic amylase and intestinal enzymes hydrolyze starches and sugars into monosaccharides like glucose and fructose which are then absorbed into the bloodstream. Certain carbohydrates like cellulose are not digested but provide fiber.
1) Lipids are digested in the mouth, stomach, and small intestine by lingual lipase, gastric lipase, and pancreatic lipase respectively.
2) In the small intestine, bile salts emulsify lipids and pancreatic lipase breaks down triglycerides into fatty acids and monoacylglycerols.
3) The products of lipid digestion including fatty acids, monoacylglycerols, and cholesterol form mixed micelles that ferry the lipids to the intestinal mucosa where they are absorbed.
Carbohydrates are digested in the mouth by salivary amylase and in the small intestine by pancreatic amylase and intestinal enzymes. Monosaccharides like glucose are absorbed into the bloodstream through active transport involving sodium-glucose transporters in the intestinal walls. Glucose is the primary fuel for cells and its uptake is mediated by glucose transporters, especially GLUT2 and GLUT4 which are regulated by insulin. Deficiencies in disaccharide-digesting enzymes can cause issues like lactose intolerance and related symptoms.
Digestion & absorption of carbohydratesakina hasan
This document summarizes the digestion and absorption of carbohydrates. It begins by outlining the types of carbohydrates present in the diet and how they are broken down by enzymes into simpler monosaccharides. It then details the specific enzymes involved in digesting carbohydrates at each step, from salivary amylase in the mouth to pancreatic amylase and disaccharidases in the small intestine. Absorption of monosaccharides like glucose, galactose and fructose occurs via active transport in the intestinal epithelium. Clinical examples like lactose intolerance are also discussed.
Digestion and absorption of carbohydrateHerat Soni
This document summarizes the digestion and absorption of carbohydrates. It states that carbohydrates in the diet are primarily complex polysaccharides that are broken down by enzymes into monosaccharides in the gastrointestinal tract. The breakdown process begins in the mouth with salivary amylase and continues in the pancreas with pancreatic amylase and in the small intestine with enzymes that break down disaccharides into monosaccharides. Only monosaccharides can be absorbed into the intestinal cells, primarily through co-transport with sodium ions. The monosaccharides are then released into the bloodstream through facilitated diffusion transporters.
1. Digestion breaks down carbohydrates into monosaccharides like glucose and fructose. Salivary amylase and enzymes in the small intestine like maltase, lactase, and sucrase aid in this process.
2. Monosaccharides are absorbed into the bloodstream via active transport against concentration gradients or facilitated diffusion. Glucose is transported to tissues like the liver and brain, while pentoses are excreted by the kidneys.
3. Lactose intolerance occurs when lactase enzyme is deficient, causing undigested lactose to pass to the colon and cause gas, bloating, and diarrhea.
This document summarizes carbohydrate digestion in the human gastrointestinal tract. It describes how carbohydrates are broken down into smaller molecules by salivary and pancreatic amylases and intestinal disaccharidases and oligosaccharidases. The monosaccharides glucose, fructose and galactose that are produced are then absorbed into the bloodstream in the small intestine. Glucose absorption is an active process that utilizes sodium-glucose co-transporters, while fructose absorption occurs via facilitated diffusion. Factors that can influence carbohydrate absorption such as intestinal health, hormones and vitamins are also discussed.
This document summarizes carbohydrate metabolism, including the absorption of monosaccharides, fate of absorbed sugars, pathways for glucose utilization, oxidation of glucose through glycolysis and the Krebs cycle, and glycogen metabolism. Key points include: monosaccharides are absorbed via simple diffusion, facilitated transport, or active transport; glucose is utilized through oxidation, storage, or conversion to other compounds; glycolysis occurs via two phases to generate ATP or lactate; the Krebs cycle further oxidizes pyruvate to generate more ATP; glycogen is synthesized from and broken down back to glucose to provide energy.
The document summarizes the process of carbohydrate digestion in humans. It begins with mechanical digestion in the mouth through chewing. Chemical digestion then starts with salivary amylase breaking down some starch in the mouth. In the stomach, further mixing occurs and ptyalin continues breaking down starch, with around 30-40% being digested. The acidic stomach stops further digestion. In the small intestine, pancreatic amylase and intestinal enzymes hydrolyze starches and sugars into monosaccharides like glucose and fructose which are then absorbed into the bloodstream. Certain carbohydrates like cellulose are not digested but provide fiber.
1) Lipids are digested in the mouth, stomach, and small intestine by lingual lipase, gastric lipase, and pancreatic lipase respectively.
2) In the small intestine, bile salts emulsify lipids and pancreatic lipase breaks down triglycerides into fatty acids and monoacylglycerols.
3) The products of lipid digestion including fatty acids, monoacylglycerols, and cholesterol form mixed micelles that ferry the lipids to the intestinal mucosa where they are absorbed.
Glycogen is a branched polymer of glucose residues that serves as a storage form of glucose. It is composed mainly of α-1,4 glycosidic linkages with branches every tenth residue by α-1,6 linkages. Glycogen is found primarily in liver and muscle cells bound in granules and provides a readily available source of glucose through breakdown. Glycogen synthesis utilizes UDP-glucose and glycogenin to initiate polymer formation, while breakdown is catalyzed by phosphorylase releasing glucose-1-phosphate and other enzymes are needed to further process the glucose for energy production.
Class 1 digestion and absorption of carbohydrateDhiraj Trivedi
Dr. Dhiraj J. Trivedi presenting Lecture on Carbohydrate metabolism for medical students.
Professor, SDM College of Medical Sciences, Dharwad, Karnataka, India
This document discusses glycogenesis and glycogenolysis. Glycogenesis is the process by which glucose is polymerized into glycogen in the liver and skeletal muscles. It involves phosphorylation of glucose, synthesis of UDP-glucose, addition of glucose units to glycogen by glycogen synthase, and branching of glycogen chains. Glycogenolysis is the breakdown of glycogen into glucose-1-phosphate. It involves cleavage of glycosidic bonds by glycogen phosphorylase and debranching enzyme. Glycogen levels are regulated by hormones like epinephrine, glucagon, and insulin which target glycogen phosphorylase and glycogen synthase.
Gluconeogenesis is the process by which glucose is synthesized from non-carbohydrate precursors like lactate, glycerol, and certain amino acids. It mainly takes place in the liver and kidneys. Key steps involve the conversion of pyruvate to oxaloacetate and regulation of enzymes like PEP carboxykinase and fructose-1,6-bisphosphatase. Gluconeogenesis is important for maintaining blood glucose levels during fasting or starvation when carbohydrate sources are limited.
Glycogenolysis is the breakdown of glycogen into glucose-1-phosphate. It occurs in three steps:
1) Phosphorolysis by glycogen phosphorylase cleaves α-1,4 glycosidic linkages, producing glucose-1-phosphate until four glucose residues remain.
2) A debranching enzyme removes these four residue branches through two activities, producing linear chains of glucose residues.
3) Phosphoglucomutase converts glucose-1-phosphate to glucose-6-phosphate, which can then enter glycolysis to produce energy or be released as free glucose from the liver. Glycogenolysis is regulated by allosteric effectors, hormones like glucagon and
Carbohydrate digestion is a mechanical and chemical breakdown of polysaccharides into monosaccharides like glucose, galactose and fructose. It involves enzymes that hydrolyze bonds between sugar molecules. Starch and glycogen are broken down by salivary and pancreatic enzymes into smaller molecules as they move through the mouth, stomach and small intestine. Final digestion occurs via disaccharidases in the jejunum wall, absorbing the monosaccharides. Deficiencies in these enzymes can cause osmotic diarrhea due to undigested carbohydrates fermenting in the colon.
Lipids undergo a multi-step digestion and absorption process in the gastrointestinal tract. Dietary lipids are emulsified and broken down into smaller components like fatty acids and monoacylglycerols by lingual and gastric lipases in the stomach and pancreatic lipase in the small intestine. Bile salts produced by the liver play a key role in emulsification. The products of digestion are incorporated into micelles and absorbed by intestinal cells. Inside cells, fatty acids are reassembled into triglycerides and packaged into chylomicrons that enter the lymphatic system and bloodstream for transport to tissues. Defects in digestion, emulsification, or absorption can impair this process.
This document discusses carbohydrate metabolism and energy production. It explains that ATP is the energy currency of cells and is produced through substrate-level phosphorylation and oxidative phosphorylation. Glucose is the main carbohydrate and can be stored as glycogen, metabolized for energy through glycolysis and the TCA cycle, or stored as fat. Glycolysis converts glucose to pyruvate, and pyruvate can then be converted to lactate, alanine, or enter the TCA cycle. The TCA cycle generates energy carriers that are used in the electron transport chain to produce large amounts of ATP through oxidative phosphorylation.
Digestion & absorption of carbohydrate.pptxABHIJIT BHOYAR
The goal of carbohydrate digestion is to break down all disaccharides and complex carbohydrates into monosaccharides for absorption, although not all are completely absorbed in the small intestine (e.g., fiber). Digestion begins in the mouth with salivary amylase released during the process of chewing.
The document summarizes the digestion and absorption of proteins in the human body. Dietary and endogenous proteins are broken down through digestion by enzymes in the stomach, pancreas, and intestines. In the stomach, pepsin digests proteins into proteoses and peptones. The pancreas secretes trypsin, chymotrypsin, and other enzymes as zymogens which are activated and further break down proteins. In the intestines, aminopeptidases and dipeptidases break down peptides into amino acids, which are then absorbed into the bloodstream through active transport mechanisms.
1. Lipids play major roles in cell structure and energy storage. Triacylglycerols are the main form of stored energy in mammals while phospholipids and cholesterol are components of cell membranes.
2. There are two main types of lipids - simple lipids like fats and oils which are esters of fatty acids and alcohols, and compound lipids which also contain phosphate, nitrogenous bases or other groups.
3. Triglycerides from the diet and from adipose tissue are broken down into fatty acids and glycerol. Fatty acids are transported to tissues via the bloodstream bound to albumin or within lipoproteins, then undergo beta-oxidation in the mitochondria to
Carbohydrates are digested into monosaccharides like glucose, fructose, and galactose which are then absorbed in the small intestine. Glucose accounts for about 80% of absorbed monosaccharides and is actively transported into intestinal cells via sodium-glucose transporters, using the sodium gradient as an energy source. Galactose absorption is similar to glucose while fructose absorption occurs via facilitated diffusion without requiring sodium or energy. Absorption rates vary between sugars with galactose absorbing most rapidly, followed by glucose, then fructose and pentoses absorbing slowest. Health of the intestinal mucosa and various hormones can also impact carbohydrate absorption rates.
Fructose is metabolized primarily in the liver and small intestine. In the liver, fructose is converted to fructose-1-phosphate by fructokinase using ATP as energy. Fructose-1-phosphate is then cleaved by aldolase B into glyceraldehyde and dihydroxyacetone phosphate, which both enter glycolysis to generate energy. This pathway allows fructose to be rapidly metabolized and generates intermediates for glycolysis, though it requires two ATP per fructose molecule. Disorders of this pathway can cause hypoglycemia or liver failure if not treated by avoiding dietary fructose and sucrose.
Carbohydrates are digested in the mouth by salivary amylase and in the small intestine by pancreatic amylase and intestinal enzymes. These enzymes break down starches and sugars into monosaccharides like glucose, galactose and fructose, which are then absorbed into the bloodstream. Some common disorders of carbohydrate digestion include lactose intolerance, due to a deficiency of lactase, and sucrase deficiency, due to a lack of the enzyme sucrase. These disorders can cause abdominal symptoms like cramps and diarrhea.
This document summarizes the digestion and absorption of carbohydrates. It notes that carbohydrates are broken down into monosaccharides like glucose, fructose, and galactose by enzymes in the mouth and small intestine. These monosaccharides are then absorbed actively through the small intestine. Glucose absorption uses active transport involving sodium-glucose transporters, while fructose absorption occurs through facilitated diffusion. Factors like thyroid hormones can affect carbohydrate absorption rates. Conditions like lactose intolerance can also impact digestion if digestive enzymes are absent.
Carbohydrates are organic compounds that serve as a major source of energy. They are classified based on their structure as monosaccharides, disaccharides, or polysaccharides. Common monosaccharides include glucose, fructose, and galactose. Important disaccharides are sucrose, lactose, and maltose. Starch and cellulose are examples of polysaccharides. Carbohydrates can be identified using chemical tests such as Molisch, Fehling's, Benedict's, Barfoed, and iodine tests. These tests identify carbohydrates based on properties such as being reducing or non-reducing sugars.
This document summarizes the digestion and absorption of carbohydrates. It discusses that carbohydrates are broken down into monosaccharides in the mouth by salivary amylase, pass undigested through the stomach, and are further broken down in the small intestine by pancreatic amylase and intestinal disaccharidases into absorbable monosaccharides like glucose, fructose and galactose. These monosaccharides are then absorbed into the bloodstream through active transport using sodium-glucose transporters or facilitated diffusion using glucose transporters. Lactose intolerance results if the enzyme lactase is deficient and lactose cannot be fully digested.
The document summarizes carbohydrate digestion and metabolism. Carbohydrates are digested by enzymes in the mouth, stomach, and small intestine into monosaccharides like glucose, galactose, and fructose. These are then absorbed into the bloodstream and tissues. Glucose is the primary fuel for cellular respiration and can be stored or used to make other biomolecules. Glycolysis converts glucose to pyruvate in the cytoplasm and generates a small amount of ATP. Aerobic glycolysis provides more ATP through oxidation of pyruvate in the mitochondria.
Carbohydrates are digested by enzymes into monosaccharides like glucose, galactose and fructose. They are absorbed into the bloodstream and transported to tissues. In the mouth, starch is broken down into maltose and dextrins by salivary amylase. In the small intestine, pancreatic amylase further breaks starches into maltose and isomaltose while disaccharidases break down lactose, sucrose and isomaltose. Cellulose is not digested. Glucose, galactose and fructose are absorbed via active transport mediated by carriers or passive diffusion, entering the liver and tissues to be used for energy or storage. Undigested carbo
Glycogen is a branched polymer of glucose residues that serves as a storage form of glucose. It is composed mainly of α-1,4 glycosidic linkages with branches every tenth residue by α-1,6 linkages. Glycogen is found primarily in liver and muscle cells bound in granules and provides a readily available source of glucose through breakdown. Glycogen synthesis utilizes UDP-glucose and glycogenin to initiate polymer formation, while breakdown is catalyzed by phosphorylase releasing glucose-1-phosphate and other enzymes are needed to further process the glucose for energy production.
Class 1 digestion and absorption of carbohydrateDhiraj Trivedi
Dr. Dhiraj J. Trivedi presenting Lecture on Carbohydrate metabolism for medical students.
Professor, SDM College of Medical Sciences, Dharwad, Karnataka, India
This document discusses glycogenesis and glycogenolysis. Glycogenesis is the process by which glucose is polymerized into glycogen in the liver and skeletal muscles. It involves phosphorylation of glucose, synthesis of UDP-glucose, addition of glucose units to glycogen by glycogen synthase, and branching of glycogen chains. Glycogenolysis is the breakdown of glycogen into glucose-1-phosphate. It involves cleavage of glycosidic bonds by glycogen phosphorylase and debranching enzyme. Glycogen levels are regulated by hormones like epinephrine, glucagon, and insulin which target glycogen phosphorylase and glycogen synthase.
Gluconeogenesis is the process by which glucose is synthesized from non-carbohydrate precursors like lactate, glycerol, and certain amino acids. It mainly takes place in the liver and kidneys. Key steps involve the conversion of pyruvate to oxaloacetate and regulation of enzymes like PEP carboxykinase and fructose-1,6-bisphosphatase. Gluconeogenesis is important for maintaining blood glucose levels during fasting or starvation when carbohydrate sources are limited.
Glycogenolysis is the breakdown of glycogen into glucose-1-phosphate. It occurs in three steps:
1) Phosphorolysis by glycogen phosphorylase cleaves α-1,4 glycosidic linkages, producing glucose-1-phosphate until four glucose residues remain.
2) A debranching enzyme removes these four residue branches through two activities, producing linear chains of glucose residues.
3) Phosphoglucomutase converts glucose-1-phosphate to glucose-6-phosphate, which can then enter glycolysis to produce energy or be released as free glucose from the liver. Glycogenolysis is regulated by allosteric effectors, hormones like glucagon and
Carbohydrate digestion is a mechanical and chemical breakdown of polysaccharides into monosaccharides like glucose, galactose and fructose. It involves enzymes that hydrolyze bonds between sugar molecules. Starch and glycogen are broken down by salivary and pancreatic enzymes into smaller molecules as they move through the mouth, stomach and small intestine. Final digestion occurs via disaccharidases in the jejunum wall, absorbing the monosaccharides. Deficiencies in these enzymes can cause osmotic diarrhea due to undigested carbohydrates fermenting in the colon.
Lipids undergo a multi-step digestion and absorption process in the gastrointestinal tract. Dietary lipids are emulsified and broken down into smaller components like fatty acids and monoacylglycerols by lingual and gastric lipases in the stomach and pancreatic lipase in the small intestine. Bile salts produced by the liver play a key role in emulsification. The products of digestion are incorporated into micelles and absorbed by intestinal cells. Inside cells, fatty acids are reassembled into triglycerides and packaged into chylomicrons that enter the lymphatic system and bloodstream for transport to tissues. Defects in digestion, emulsification, or absorption can impair this process.
This document discusses carbohydrate metabolism and energy production. It explains that ATP is the energy currency of cells and is produced through substrate-level phosphorylation and oxidative phosphorylation. Glucose is the main carbohydrate and can be stored as glycogen, metabolized for energy through glycolysis and the TCA cycle, or stored as fat. Glycolysis converts glucose to pyruvate, and pyruvate can then be converted to lactate, alanine, or enter the TCA cycle. The TCA cycle generates energy carriers that are used in the electron transport chain to produce large amounts of ATP through oxidative phosphorylation.
Digestion & absorption of carbohydrate.pptxABHIJIT BHOYAR
The goal of carbohydrate digestion is to break down all disaccharides and complex carbohydrates into monosaccharides for absorption, although not all are completely absorbed in the small intestine (e.g., fiber). Digestion begins in the mouth with salivary amylase released during the process of chewing.
The document summarizes the digestion and absorption of proteins in the human body. Dietary and endogenous proteins are broken down through digestion by enzymes in the stomach, pancreas, and intestines. In the stomach, pepsin digests proteins into proteoses and peptones. The pancreas secretes trypsin, chymotrypsin, and other enzymes as zymogens which are activated and further break down proteins. In the intestines, aminopeptidases and dipeptidases break down peptides into amino acids, which are then absorbed into the bloodstream through active transport mechanisms.
1. Lipids play major roles in cell structure and energy storage. Triacylglycerols are the main form of stored energy in mammals while phospholipids and cholesterol are components of cell membranes.
2. There are two main types of lipids - simple lipids like fats and oils which are esters of fatty acids and alcohols, and compound lipids which also contain phosphate, nitrogenous bases or other groups.
3. Triglycerides from the diet and from adipose tissue are broken down into fatty acids and glycerol. Fatty acids are transported to tissues via the bloodstream bound to albumin or within lipoproteins, then undergo beta-oxidation in the mitochondria to
Carbohydrates are digested into monosaccharides like glucose, fructose, and galactose which are then absorbed in the small intestine. Glucose accounts for about 80% of absorbed monosaccharides and is actively transported into intestinal cells via sodium-glucose transporters, using the sodium gradient as an energy source. Galactose absorption is similar to glucose while fructose absorption occurs via facilitated diffusion without requiring sodium or energy. Absorption rates vary between sugars with galactose absorbing most rapidly, followed by glucose, then fructose and pentoses absorbing slowest. Health of the intestinal mucosa and various hormones can also impact carbohydrate absorption rates.
Fructose is metabolized primarily in the liver and small intestine. In the liver, fructose is converted to fructose-1-phosphate by fructokinase using ATP as energy. Fructose-1-phosphate is then cleaved by aldolase B into glyceraldehyde and dihydroxyacetone phosphate, which both enter glycolysis to generate energy. This pathway allows fructose to be rapidly metabolized and generates intermediates for glycolysis, though it requires two ATP per fructose molecule. Disorders of this pathway can cause hypoglycemia or liver failure if not treated by avoiding dietary fructose and sucrose.
Carbohydrates are digested in the mouth by salivary amylase and in the small intestine by pancreatic amylase and intestinal enzymes. These enzymes break down starches and sugars into monosaccharides like glucose, galactose and fructose, which are then absorbed into the bloodstream. Some common disorders of carbohydrate digestion include lactose intolerance, due to a deficiency of lactase, and sucrase deficiency, due to a lack of the enzyme sucrase. These disorders can cause abdominal symptoms like cramps and diarrhea.
This document summarizes the digestion and absorption of carbohydrates. It notes that carbohydrates are broken down into monosaccharides like glucose, fructose, and galactose by enzymes in the mouth and small intestine. These monosaccharides are then absorbed actively through the small intestine. Glucose absorption uses active transport involving sodium-glucose transporters, while fructose absorption occurs through facilitated diffusion. Factors like thyroid hormones can affect carbohydrate absorption rates. Conditions like lactose intolerance can also impact digestion if digestive enzymes are absent.
Carbohydrates are organic compounds that serve as a major source of energy. They are classified based on their structure as monosaccharides, disaccharides, or polysaccharides. Common monosaccharides include glucose, fructose, and galactose. Important disaccharides are sucrose, lactose, and maltose. Starch and cellulose are examples of polysaccharides. Carbohydrates can be identified using chemical tests such as Molisch, Fehling's, Benedict's, Barfoed, and iodine tests. These tests identify carbohydrates based on properties such as being reducing or non-reducing sugars.
This document summarizes the digestion and absorption of carbohydrates. It discusses that carbohydrates are broken down into monosaccharides in the mouth by salivary amylase, pass undigested through the stomach, and are further broken down in the small intestine by pancreatic amylase and intestinal disaccharidases into absorbable monosaccharides like glucose, fructose and galactose. These monosaccharides are then absorbed into the bloodstream through active transport using sodium-glucose transporters or facilitated diffusion using glucose transporters. Lactose intolerance results if the enzyme lactase is deficient and lactose cannot be fully digested.
The document summarizes carbohydrate digestion and metabolism. Carbohydrates are digested by enzymes in the mouth, stomach, and small intestine into monosaccharides like glucose, galactose, and fructose. These are then absorbed into the bloodstream and tissues. Glucose is the primary fuel for cellular respiration and can be stored or used to make other biomolecules. Glycolysis converts glucose to pyruvate in the cytoplasm and generates a small amount of ATP. Aerobic glycolysis provides more ATP through oxidation of pyruvate in the mitochondria.
Carbohydrates are digested by enzymes into monosaccharides like glucose, galactose and fructose. They are absorbed into the bloodstream and transported to tissues. In the mouth, starch is broken down into maltose and dextrins by salivary amylase. In the small intestine, pancreatic amylase further breaks starches into maltose and isomaltose while disaccharidases break down lactose, sucrose and isomaltose. Cellulose is not digested. Glucose, galactose and fructose are absorbed via active transport mediated by carriers or passive diffusion, entering the liver and tissues to be used for energy or storage. Undigested carbo
1) Carbohydrates in food are broken down into monosaccharides like glucose, galactose, and fructose through the actions of salivary and pancreatic amylases and intestinal disaccharidases.
2) These monosaccharides are then actively transported across the intestinal mucosa into the bloodstream or passively diffuse for absorption.
3) Once absorbed, monosaccharides are used for energy production, storage as glycogen or fat, or converted into other biologically important substances in tissues like the liver.
1. Carbohydrate digestion begins in the mouth and small intestine through enzymes like amylase and disaccharidases.
2. Further digestion by pancreatic enzymes occurs in the small intestine through enzymes like pancreatic amylase.
3. Final digestion is carried out by enzymes in the intestinal mucosal cells, breaking down sugars into monosaccharides that can be absorbed.
This document provides an overview of carbohydrate metabolism. It discusses:
1) The digestion of carbohydrates in the mouth, stomach, and small intestine by enzymes like amylase and disaccharidases into monosaccharides like glucose, galactose, and fructose.
2) The absorption of monosaccharides into the bloodstream and their fate in tissues through pathways like glycolysis and glycogenesis.
3) Glycolysis, the breakdown of glucose to pyruvate with production of ATP, and its regulation and clinical significance.
The document summarizes carbohydrate metabolism. It discusses the digestion, absorption, and utilization of carbohydrates. Carbohydrate digestion occurs via salivary and pancreatic amylases in the mouth and small intestine, breaking down starches and glycogen into disaccharides and trisaccharides that are then further broken down by intestinal enzymes. Absorption occurs mainly in the jejunum via both active and facilitated transport. Glucose is then distributed to tissues via the bloodstream and undergoes glycolysis and other pathways to produce energy or be used for biosynthesis. Glycolysis is discussed in detail, including its regulation by key enzymes and hormones.
Carbohydrates are the largest source of calories and are broken down into glucose, which is the main carbohydrate used for energy in the body. Carbohydrates are digested by enzymes in the mouth, stomach and intestines into monosaccharides like glucose that can be absorbed. Glucose is then transported via blood to tissues like muscle where it is used for energy production or stored as glycogen in the liver and muscle. The regulation of carbohydrate metabolism involves hormones like insulin and glucagon that control glucose uptake, storage and production to maintain blood glucose levels.
Carbohydrates are the largest source of calories and are broken down into glucose, which is the main carbohydrate used in metabolism. Glucose is absorbed into the bloodstream and transported to tissues like muscle where it is either used for energy or stored as glycogen. Carbohydrate digestion begins in the mouth and small intestine where enzymes break starches and sugars into glucose and other monosaccharides that can be absorbed. Glucose is then regulated through various pathways including glycolysis, the citric acid cycle, and oxidative phosphorylation to produce energy in the form of ATP.
This document provides an introduction to carbohydrates and glycolysis. It defines carbohydrates and their main functions. Carbohydrates are classified into monosaccharides, oligosaccharides, and polysaccharides. Monosaccharides include glucose, fructose, and galactose. Glycolysis is described as the breakdown of glucose to pyruvate or lactate with production of ATP. Key steps of glycolysis include conversion of glucose to glucose-6-phosphate and production of two ATP molecules. Glycolysis occurs in the cytosol and is the first step of glucose metabolism, providing energy and intermediates for other pathways.
Cell body defense CBD DIGESTION-GLYCOLYSIS.pptxAlabiDavid4
This document provides an overview of carbohydrate digestion, absorption, and metabolism. It discusses:
- The breakdown of ingested carbohydrates (starch, lactose, sucrose) into monomers like glucose, fructose, and galactose by enzymes in the digestive tract.
- The transport of these monomers across intestinal cells and into the bloodstream, facilitated by sodium-dependent and facilitative glucose transporters.
- The major pathways of glucose metabolism, including glycolysis. Glycolysis converts glucose to pyruvate, generating a small amount of ATP both aerobically and anaerobically in most cells.
- Tissues and cell types rely heavily on glycolysis, like red blood
This document discusses carbohydrate chemistry, metabolism, and regulation. It covers:
- The structure and classification of carbohydrates including monosaccharides, disaccharides, oligosaccharides, and polysaccharides.
- The digestion of carbohydrates in the mouth, stomach, and small intestine by enzymes that break down polysaccharides and oligosaccharides into monosaccharides like glucose, which are then absorbed.
- The metabolism of glucose through three main pathways: glycolysis, the tricarboxylic acid cycle, and oxidative phosphorylation to generate cellular energy. Glycolysis occurs anaerobically in the cytosol and aerobically in the mitochondria.
- The regulation of blood glucose levels through pathways
The document provides an overview of carbohydrate metabolism. It discusses the main dietary sources of carbohydrates and their functions, including providing energy. It describes the digestion of carbohydrates by salivary, pancreatic and intestinal enzymes into monosaccharides that are absorbed into the bloodstream. Glucose and galactose enter cells via active transport while fructose uses facilitated diffusion. The liver plays a key role in carbohydrate metabolism, storing glucose and releasing it into circulation. Tissues take up glucose via different glucose transporters. The document outlines several major pathways involved in carbohydrate metabolism.
Carbohydrate digestion involves hydrolysis of carbohydrates into smaller molecules by enzymes. Starch is broken down by salivary amylase and pancreatic amylase in the mouth and small intestine. Disaccharides are further broken down by disaccharidases in the small intestine. Glucose is absorbed into the bloodstream via GLUT transporters in the intestinal mucosa. Glycolysis is the pathway that breaks down glucose to pyruvate, generating ATP through substrate-level phosphorylation. It occurs in the cytosol of cells and is regulated by enzymes like hexokinase, phosphofructokinase, and pyruvate kinase.
This document summarizes the metabolism of carbohydrates. It discusses that carbohydrates provide the largest component of the diet and their main function is to supply energy. It describes the digestion of carbohydrates by salivary, pancreatic and intestinal enzymes into monosaccharides that can be absorbed. The major pathways of carbohydrate metabolism are then outlined as glycolysis, the hexose monophosphate shunt, glycogenesis, glycogenolysis and gluconeogenesis. The key steps of glycolysis including the preparatory, splitting and oxidative phases are detailed.
Diegestion Absorption of CHO and Hexose sugar metabolism.pdfTeshaleTekle1
The document discusses the digestion and absorption of carbohydrates. It begins by describing the different types of dietary carbohydrates and the enzymes involved in digesting them in the mouth, stomach, and small intestine. These include salivary amylase, pancreatic amylase, intestinal mucosal enzymes, and disaccharidases. Non-digestible fibers are also mentioned. The absorption of monosaccharides by active transport and facilitated diffusion is summarized. Defects in carbohydrate digestion and absorption and the metabolism of sugars other than glucose are briefly covered.
The document discusses carbohydrate metabolism. It begins with an introduction to nutrition and carbohydrates, classifying carbohydrates and their functions. It then outlines the major pathways of carbohydrate metabolism, including glycolysis, the citric acid cycle, gluconeogenesis, glycogen metabolism, the hexose monophosphate shunt, and the metabolism of galactose, fructose, and amino sugars. Clinical aspects related to deficiencies in these pathways are also mentioned.
This document provides an introduction to carbohydrates and glycolysis. It defines carbohydrates and their main functions. Carbohydrates are classified as monosaccharides, oligosaccharides, or polysaccharides. Monosaccharides include glucose, fructose, and galactose. Glycolysis breaks down glucose to pyruvate or lactate with production of a small amount of ATP. Glycolysis occurs in the cytosol and is the first step of carbohydrate metabolism both aerobically and anaerobically.
Carbohydrate is an organic compound that consists only of carbon (C), hydrogen & oxygen. The primary function of carbohydrates is to provide energy for the body.
Simple carbohydrates have one or two sugar molecules.
Complex carbohydrates have three or more sugar molecules, such as legumes, bread, rice, pasta.
Debridement is an important component of the wound bed preparation (WBP) management Model.
Cause of the wound and patient-centered concerns, debridement is a necessary step in local wound care.
Debridement is the removal of necrotic tissue, exudate, bacteria, and metabolic waste from a wound in order to improve or facilitate the healing process
Chest pain or discomfort
Common presenting symptom of cardiovascular disease
May be cardiac or noncardiac in origin.
Cardiac – angina, MI, pericarditis, mitral valve prolapse, dissecting aortic aneurysm
Non cardiac – anemia (physical exertion), cervical disc disease, anxiety, trigger points etc
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Radiating pain to neck, jaw, upper trapezius, upper back, shoulder or arms (commonly left
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Biologist & gerontologist used concept of senescence to explain biological aging
Senescence or normal aging refers to a gradual, time related to biological process that takes places as degenerative processes overtake regenerative or growth processes.
or
senescence: a change in the behavior of an organism with age leading to a decreased power of survival and adjustment
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There are natural and synthetic immunomodulatory agents .
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non-skeletal mesodermal tissues: adipose tissue, fibrous tissue, muscle, blood vessels and peripheral nerves (despite neuroectodermal origin)
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It’s normally due to an injury or a headache, occasionally facial pain may also be due to neurological or vascular causes, but equally well may be dental in origin.
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Eating a diet high in vegetables, fruits, whole grains, and legumes.
Choosing lean, low-fat sources of protein.
Limiting sweets, soft drinks, and foods with added sugar.
Including proteins, carbohydrates, and a little good fat in all meals and snacks.
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Explore the benefits of combining Ayurveda with conventional Parkinson's treatments. Learn how a holistic approach can manage symptoms, enhance well-being, and balance body energies. Discover the steps to safely integrate Ayurvedic practices into your Parkinson’s care plan, including expert guidance on diet, herbal remedies, and lifestyle modifications.
8 Surprising Reasons To Meditate 40 Minutes A Day That Can Change Your Life.pptxHolistified Wellness
We’re talking about Vedic Meditation, a form of meditation that has been around for at least 5,000 years. Back then, the people who lived in the Indus Valley, now known as India and Pakistan, practised meditation as a fundamental part of daily life. This knowledge that has given us yoga and Ayurveda, was known as Veda, hence the name Vedic. And though there are some written records, the practice has been passed down verbally from generation to generation.
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There is increasing confidence that cell therapies will soon play a role in the treatment of autoimmune disorders, but the extent of this impact remains to be seen. Early readouts on autologous CAR-Ts in lupus are encouraging, but manufacturing and cost limitations are likely to restrict access to highly refractory patients. Allogeneic CAR-Ts have the potential to broaden access to earlier lines of treatment due to their inherent cost benefits, however they will need to demonstrate comparable or improved efficacy to established modalities.
In addition to infrastructure and capacity constraints, CAR-Ts face a very different risk-benefit dynamic in autoimmune compared to oncology, highlighting the need for tolerable therapies with low adverse event risk. CAR-NK and Treg-based therapies are also being developed in certain autoimmune disorders and may demonstrate favorable safety profiles. Several novel non-cell therapies such as bispecific antibodies, nanobodies, and RNAi drugs, may also offer future alternative competitive solutions with variable value propositions.
Widespread adoption of cell therapies will not only require strong efficacy and safety data, but also adapted pricing and access strategies. At oncology-based price points, CAR-Ts are unlikely to achieve broad market access in autoimmune disorders, with eligible patient populations that are potentially orders of magnitude greater than the number of currently addressable cancer patients. Developers have made strides towards reducing cell therapy COGS while improving manufacturing efficiency, but payors will inevitably restrict access until more sustainable pricing is achieved.
Despite these headwinds, industry leaders and investors remain confident that cell therapies are poised to address significant unmet need in patients suffering from autoimmune disorders. However, the extent of this impact on the treatment landscape remains to be seen, as the industry rapidly approaches an inflection point.
Rasamanikya is a excellent preparation in the field of Rasashastra, it is used in various Kushtha Roga, Shwasa, Vicharchika, Bhagandara, Vatarakta, and Phiranga Roga. In this article Preparation& Comparative analytical profile for both Formulationon i.e Rasamanikya prepared by Kushmanda swarasa & Churnodhaka Shodita Haratala. The study aims to provide insights into the comparative efficacy and analytical aspects of these formulations for enhanced therapeutic outcomes.
2. I. Introduction:
A. More than 60% of our foods are carbohydrates.
Starch, glycogen, sucrose, lactose and cellulose are
the chief carbohydrates in our food. Before intestinal
absorption, they are hydrolysed to hexose sugars
(glucose, galactose and fructose).
B. A family of a glycosidases that degrade
carbohydrate into their monohexose components
catalyzes hydrolysis of glycocidic bonds. These
enzymes are usually specific to the type of bond to
be broken.
3. Digestion of carbohydrate by salivary α -amylase (ptylin)
in the mouth:
A. This enzyme is produced by salivary glands. Its optimum pH is
6.7.
B. It is activated by chloride ions (cl-).
C. It acts on cooked starch and glycogen breaking α 1-4 bonds,
converting them into maltose [a disaccharide containing two
glucose molecules attached by α 1-4 linkage]. This bond is not
attacked by alpha-amylase.
Because both starch and glycogen also contain 1-6 bonds, the
resulting digest contains isomaltose [a disaccharide in which two
glucose molecules are attached by 1-6 linkage].
E. Because food remains for a short time in the mouth, digestion of
starch and glycogen may be incomplete and gives a partial
digestion products called: starch dextrins (amylodextrin,
erythrodextrin and achrodextrin).
F. Therefore, digestion of starch and glycogen in the mouth gives
maltose, isomaltose and starch dextrins.
4. ln the stomach: carbohydrate digestion stops
temporarily due to the high acidity which
inactivates the salivary - amylase.
IV. Digestion of carbohydrate by the pancreatic - amylase small
intestine in the small intestine.
A. α-amylase enzyme is produced by pancreas and acts in small
intestine. Its optimum pH is 7.1.
B. It is also activated by chloride ions.
C. It acts on cooked and uncooked starch, hydrolysing them into
maltose and isomaltose.
Final carbohydrate digestion by intestinal enzymes:
A. The final digestive processes occur at the small intestine and
include the action of several disaccharidases. These enzymes
are secreted through and remain associated with the brush
border of the intestinal mucosal cells.
5. B. The disaccharidases include:
1. Lactase (β-galactosidase) which hydrolyses lactose into two
molecules of glucose and galactose:
Lactase
Lactose Glucose + Galactose
2. Maltase ( α-glucosidase), which hydrolyses maltose into two
molecules of glucose:
Maltase
Maltose Glucose + Glucose
3. Sucrose (α-fructofuranosidase), which hydrolyses sucrose into
two molecules of glucose and fructose:
Sucrose
Sucrose Glucose + Fructose
4. α - dextrinase (oligo-1,6 glucosidase) which hydrolyze (1 ,6)
linkage of isomaltose.
Dextrinase
Isomaltose Glucose + Glucose
6. Digestion of cellulose:
A. Cellulose contains β(1-4) bonds between glucose molecules.
B. In humans, there is no β (1-4) glucosidase that can digest
such bonds. So cellulose passes as such in stool.
C. Cellulose helps water retention during the passage of food
along the intestine producing larger and softer feces
preventing constipation.
7. Absorptions
A.The end products of carbohydrate digestion are monosaccharides:
glucose, galactose and fructose. They are absorbed from the
jejunum to portal veins to the liver, where fructose and galactose
are transformed into glucose.
B.Two mechanisms are responsible for absorption of
monosaccharides: active transport (against concentration
gradient i.e. from low to high concentration) and passive transport
(by facilitated diffusion).
C. For active transport to take place, the structure of sugar should
have:
1. Hexose ring.
2. OH group at position 2 at the right side. Both of which are present
in glucose and galactose. Fructose, which does not contain -OH
group to the right at position 2 is absorbed more slowly than
glucose and galactose by passive diffusion (slow process).
3. A methyl or a substituted methyl group should be present at
carbon 5.
I. Introduction
8. II. Mechanisms of absorption:
A. Active transport:
1. Mechanism of active transport:
a) In the cell membrane of the intestinal cells, there is a mobile
carrier protein called sodium dependant glucose transporter
(SGL T-1) It transports glucose to inside the cell using
energy. The energy is derived from sodium-potassium
pump. The transporter has 2 separate sites, one for sodium
and the other for glucose. It transports them from the
intestinal lumen across cell membrane to the cytoplasm.
Then both glucose and sodium are released into the
cytoplasm allowing the carrier to return for more transport
of glucose and sodium.
9. b) The sodium is transported from high to low concentration
(with concentration gradient) and at the same time causes the
carrier to transport glucose against its concentration gradient.
The Na+ is expelled outside the cell by sodium pump. Which
needs ATP as a source of energy. The reaction is catalyzed by
an enzyme called "Adenosine triphosphatase (ATPase)".
Active transport is much more faster than passive transport.
c) Insulin increases the number of glucose transporters in
tissues containing insulin receptors e.g. muscles and adipose
tissue.
10. B. Transport Proteins
Transport proteins = Integral membrane proteins that
transport specific molecules or ions across
biological membranes.
Protein
(Figure 8.9)
11. B. Passive transport (facilitated diffusion):
Sugars pass with concentration gradient i.e. from high to low
concentration. It needs no energy. It occurs by means of a sodium
independent facilitative transporter (GLUT -5). Fructose and
pentoses are absorbed by this mechanism. Glucose and
galactose can also use the same transporter if the concentration
gradient is favorable.
C. There is also sodium – independent transporter (GLUT-2), that
facilitates transport of sugars out of the cell i.e. to circulation.
2. Inhibitors of active transport:
a) Ouabin (cardiac glycoside): Inhibits adenosine triphosphatase
(ATPase) necessary for hydrolysis of ATP that produces energy
of sodium pump.
b) Phlorhizin; Inhibits the binding of sodium in the carrier protein.
12. Summary of types of functions of most
important glucose transporters:
SiteFunction
Intestine and renal
tubules.
Absorption of glucose
by active transport
(energy is derived from
Na+- K+ pump)
SGLT-
1
Intestine and spermFructose transport and
to a lesser extent
glucose and galactose.
GLUT -
5
-Intestine and renal
tubule
-β cells of islets-liver
Transport glucose out
of intestinal and renal
cells circulation
GLUT -
2
13. III. Defects of carbohydrate digestion and
absorption:
A. Lactase deficiency = lactose intolerance:
1. Definition:
a) This is a deficiency of lactase enzyme which digest lactose into
glucose and galactose
b) It may be:
(i) Congenital: which occurs very soon after birth (rare).
(ii) Acquired: which occurs later on in life (common).
2. Effect: The presence of lactose in intestine causes:
a) Increased osmotic pressure: So water will be drawn from the tissue
(causing dehydration) into the large intestine (causing diarrhoea).
b) Increased fermentation of lactose by bacteria: Intestinal bacteria
ferment lactose with subsequent production of CO2 gas. This causes
distention and abdominal cramps.
c) Treatment: Treatment of this disorder is simply by removing lactose
(milk) from diet.
14. B. Sucrose deficiency:
A rare condition, showing the signs and symptoms of lactase deficiency. It
occurs early in childhood.
C. Monosaccharide malabsorption:
This is a congenital condition in which glucose and galactose are absorbed
only slowly due to defect in the carrier mechanism. Because fructose is not
absorbed by the carrier system, its absorption is normal.
IV. Fate of absorbed sugars:
Monosaccharides (glucose, galactose and fructose) resulting from
carbohydrate digestion are absorbed and undergo the following:
A. Uptake by tissues (liver):
After absorption the liver takes up sugars, where galactose and fructose
are converted into glucose.
B. Glucose utilization by tissues:
Glucose may undergo as one of the following fate:
15. 1. Oxidation: through
a) Major pathways (glycolysis and Krebs' cycle) for production of energy.
b) Hexose monophosphate pathway: for production of ribose, deoxyribose
and NADPH + H+
c) Uronic acid pathway, for production of glucuronic acid, which is used in
detoxication and enters in the formation of mucopolysaccharide.
2. Storage: in the form of:
a) Glycogen: glycogenesis.
b) Fat: lipogenesis.
3. Conversion: to substances of biological importance:
a) Ribose, deoxyribose RNA and DNA.
b) Lactose milk.
c) Glucosamine, galactosamine mucopolysaccharides.
d) Glucoronic acid mucopolysaccharides.
e) Fructose in semen.
17. I. Glycolysis (Embden Meyerhof
Pathway):
A. Definition:
1. Glycolysis means oxidation of glucose to give pyruvate (in the
presence of oxygen) or lactate (in the absence of oxygen).
B. Site:
cytoplasm of all tissue cells, but it is of physiological importance in:
1. Tissues with no mitochondria: mature RBCs, cornea and lens.
2. Tissues with few mitochondria: Testis, leucocytes, medulla of the
kidney, retina, skin and gastrointestinal tract.
3. Tissues undergo frequent oxygen lack: skeletal muscles especially
during exercise.
18. C. Steps:
Stages of glycolysis
1. Stage one (the energy requiring stage):
a) One molecule of glucose is converted into two molecules of
glycerosldhyde-3-phosphate.
b) These steps requires 2 molecules of ATP (energy loss)
2. Stage two (the energy producing stage(:
a) The 2 molecules of glyceroaldehyde-3-phosphate are converted into
pyruvate (aerobic glycolysis) or lactate (anaerobic glycolysis(.
b) These steps produce ATP molecules (energy production).
D. Energy (ATP) production of glycolysis:
ATP production = ATP produced - ATP utilized
19. •In the energy investment phase, ATP provides
activation energy by phosphorylating glucose.
–This requires 2 ATP per glucose.
•In the energy payoff
phase, ATP is
produced by
substrate-level
phosphorylation
and NAD+ is
reduced to NADH.
•2 ATP (net) and
2 NADH are produced
per glucose.
Fig. 9.8
22. Energy production of glycolysis:
Net energyATP utilizedATP produced
2 ATP2ATP
From glucose to
glucose -6-p.
From fructose -6-p to
fructose 1,6 p.
4 ATP
(Substrate level
phosphorylation)
2ATP from 1,3 DPG.
2ATP from
phosphoenol
pyruvate
In absence of oxygen
(anaerobic
glycolysis)
6 ATP
Or
8 ATP
2ATP
-From glucose to
glucose -6-p.
From fructose -6-p to
fructose 1,6 p.
4 ATP
(substrate level
phosphorylation)
2ATP from 1,3 BPG.
2ATP from
phosphoenol
pyruvate.
In presence of
oxygen (aerobic
glycolysis)
+ 4ATP or 6ATP
(from oxidation of 2
NADH + H in
mitochondria).
23. E. Oxidation of extramitochondrial NADH+H+:
1. cytoplasmic NADH+H+ cannot penetrate mitochondrial membrane,
however, it can be used to produce energy (4 or 6 ATP) by respiratory
chain phosphorylation in the mitochondria.
2. This can be done by using special carriers for hydrogen of NADH+H+
These carriers are either dihydroxyacetone phosphate (Glycerophosphate
shuttle) or oxaloacetate (aspartate malate shuttle).
a) Glycerophosphate shuttle:
1) It is important in certain muscle and nerve cells.
2) The final energy produced is 4 ATP.
3) Mechanism: -
The coenzyme of cytoplasmic glycerol-3- phosphate dehydrogenase
is NAD+.
- The coenzyme of mitochodrial glycerol-3-phosphate dehydogenase is
FAD.
-Oxidation of FADH, in respiratory chain gives 2 ATP. As glycolysis
gives 2 cytoplasmic NADH + H+ 2 mitochondrial FADH, 2 x 2
ATP = 4 ATP.
b) Malate – aspartate shuttle:
1) It is important in other tissues patriculary liver and heart.
2) The final energy produced is 6 ATP.
24. Differences between aerobic and
anaerobic glycolysis:
AnaerobicAerobic
LactatePyruvate1. End product
2 ATP6 or 8 ATP2 Energy
Through Lactate
formation
Through respiration
chain in mitochondria
3. Regeneration of
NAD+
Not available as lactate
is cytoplasmic substrate
Available and 2 Pyruvate
can oxidize to give 30
ATP
4. Availability to TCA in
mitochondria
25. Substrate level phosphorylation:
This means phosphorylation of ADP to ATP at the reaction itself .in
glycolysis there are 2 examples:
- 1-3 Bisphosphoglycerate + ADP 3 Phosphoglycerate + ATP
- Phospho-enol pyruvate + ADP Enolpyruvate + ATP
I. Special features of glycolysis in RBCs:
1. Mature RBCs contain no mitochondria, thus:
a) They depend only upon glycolysis for energy production (=2 ATP).
b) Lactate is always the end product.
2. Glucose uptake by RBCs is independent on insulin hormone.
3. Reduction of met-hemoglobin: Glycolysis produces NADH+H+, which is
used for reduction of met-hemoglobin in red cells.
26. Biological importance (functions) of glycolysis:
1. Energy production:
a) anaerobic glycolysis gives 2 ATP.
b) aerobic glycolysis gives 8 ATP.
2. Oxygenation of tissues:
Through formation of 2,3 bisphosphoglycerate, which decreases the
affinity of Hemoglobin to O2.
3. Provides important intermediates:
a) Dihydroxyacetone phosphate: can give glycerol-3phosphate, which is
used for synthesis of triacylglycerols and phospholipids (lipogenesis).
b) 3 Phosphoglycerate: which can be used for synthesis of amino acid
serine.
c) Pyruvate: which can be used in synthesis of amino acid alanine.
4. Aerobic glycolysis provides the mitochondria with pyruvate, which gives
acetyl CoA Krebs' cycle.
27. Reversibility of glycolysis (Gluconeogenesis):
1. Reversible reaction means that the same enzyme can catalyzes the
reaction in both directions.
2. all reactions of glycolysis -except 3- are reversible.
3. The 3 irreversible reactions (those catalyzed by kinase enzymes) can be
reversed by using other enzymes.
Glucose-6-p Glucose
F1, 6 Bisphosphate Fructose-6-p
Pyruvate Phosphoenol pyruvate
4. During fasting, glycolysis is reversed for synthesis of glucose from non-
carbohydrate sources e.g. lactate.
This mechanism is called: Gluconeogenesis.
28. Comparison between glucokinase and
hexokinase enzymes:
HexokinaseGlucokinaase
All tissue cellsLiver only1. Site
High affinity (low km) i.e. it acts
even in the presence of low blood
glucose concentration.
Low affinity (high km) i.e. it
acts only in the presence of
high blood glucose
concentration.
2. Affinity to glucose
Glucose, galactose and fructoseGlucose only3. Substrate
No effectInduces synthesis of
glucokinase.
4. Effect of insulin
Allosterically inhibits hexokinaseNo effect5. Effect of glucose-6-p
It phosphorylates glucose inside
the body cells. This makes glucose
concentration more in blood than
inside the cells. This leads to
continuous supply of glucose for
the tissues even in the presence of
low blood glucose concentration.
Acts in liver after meals. It
removes glucose coming in
portal circulation, converting
it into glucose -6-phosphate.
6. Function
29. Importance of lactate production in anerobic
glycolysis:
1. In absence of oxygen, lactate is the end product of glycolysis:
2. In absence of oxygen, NADH + H+ is not oxidized by the
respiratory chain.
3. The conversion of pyruvate to lactate is the mechanism for
regeneration of NAD+.
4. This helps continuity of glycolysis, as the generated NAD+ will be
used once more for oxidation of another glucose molecule.
Glucose Pyruvate Lactate
30. •As pyruvate enters the mitochondrion, a
multienzyme complex modifies pyruvate to
acetyl CoA which enters the Krebs cycle in the
matrix.
–A carboxyl group is removed as CO2
–A pair of electrons is transferred from the
remaining two-carbon fragment to NAD+ to
form NADH.
–The oxidized
fragment, acetate,
combines with
coenzyme A to
form acetyl CoA.