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Digestion and Absorption of Carbohydrates

Carbohydrates store energy and are 1 of the 3 primary macronutrients (in addition to proteins and lipids). Carbohydrates are present in numerous foods, such as grains, fruits, legumes, and many vegetables. Polysaccharides, mostly in the form of starch, are the main dietary source of carbohydrates for humans. To be used as energy by humans, most carbohydrates must be digested (broken down) into monosaccharides that can be absorbed and then metabolized. The digestion of carbohydrates begins in the mouth with the action of salivary amylases. The remaining starch is further broken down by pancreatic amylase and brush border enzymes in the intestines. The oxidation of 1 g of carbohydrate provides 4 kcal of energy.

Last updated: Sep 1, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Review of Carbohydrate Structure

Classification

Table: Classifying carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates based on size
Name Definition Examples in humans
Monosaccharides Monosaccharides Single chain carbohydrates that are the most basic units of carbohydrates. They are typically colorless crystalline substances with a sweet taste and have the same general formula CNH2NON. Basics of Carbohydrates Molecules consisting of a single sugar group
  • Glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance
  • Galactose Galactose An aldohexose that occurs naturally in the d-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase causes an error in galactose metabolism called galactosemia, resulting in elevations of galactose in the blood. Lactose Intolerance
  • Fructose
    Disaccharides Disaccharides Oligosaccharides containing two monosaccharide units linked by a glycosidic bond. Basics of Carbohydrates A combination of 2 monosaccharides Monosaccharides Single chain carbohydrates that are the most basic units of carbohydrates. They are typically colorless crystalline substances with a sweet taste and have the same general formula CNH2NON. Basics of Carbohydrates
    • Maltose ( glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance + glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance)
    • Lactose ( glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance + galactose Galactose An aldohexose that occurs naturally in the d-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase causes an error in galactose metabolism called galactosemia, resulting in elevations of galactose in the blood. Lactose Intolerance)
    • Sucrose ( glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance + fructose)
      Oligosaccharides Oligosaccharides Carbohydrates consisting of between two (disaccharides) and ten monosaccharides connected by either an alpha- or beta-glycosidic link. They are found throughout nature in both the free and bound form. Basics of Carbohydrates A combination of 3‒10 monosaccharides Monosaccharides Single chain carbohydrates that are the most basic units of carbohydrates. They are typically colorless crystalline substances with a sweet taste and have the same general formula CNH2NON. Basics of Carbohydrates Usually attached to:
      • Proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis (forming glycoproteins Glycoproteins Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins. Basics of Carbohydrates)
      • Lipids Lipids Lipids are a diverse group of hydrophobic organic molecules, which include fats, oils, sterols, and waxes. Fatty Acids and Lipids (forming glycolipids Glycolipids Lipid attached to carbohydrate, outward-facing. The Cell: Cell Membrane)
        Polysaccharides Polysaccharides Basics of Carbohydrates A combination of > 10 monosaccharides Monosaccharides Single chain carbohydrates that are the most basic units of carbohydrates. They are typically colorless crystalline substances with a sweet taste and have the same general formula CNH2NON. Basics of Carbohydrates

        Glycosidic bonds

        • Connect a sugar molecule to something else
        • Covalent bonds between:
          • The -OH group on the anomeric carbon (usually C1) of a sugar
          • The -OH group of another compound (may be another sugar molecular or something else)
        • Bond formation results in loss of H2O
        • Named based on which carbons were joined together and the anomerism Anomerism Anomerism is the spatial configuration with respect to the 1st carbon atom in aldoses and 2nd carbon atom in ketoses. Basics of Carbohydrates of the anomeric carbon
          • E.g., α-1,4-glycosidic bonds joins the C1 (anomeric) carbon of the first saccharide (whose hydroxyl group was oriented in the α configuration) to the hydroxyl group on the C4 carbon of the next saccharide
        Disaccharides lactose and maltose

        Chemical structure of lactose and maltose demonstrating α versus β glycosidic bonds:
        In lactose, the anomeric carbon in galactose Galactose An aldohexose that occurs naturally in the d-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase causes an error in galactose metabolism called galactosemia, resulting in elevations of galactose in the blood. Lactose Intolerance (C1) is in the β configuration (the hydroxyl group points up); therefore, when galactose Galactose An aldohexose that occurs naturally in the d-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase causes an error in galactose metabolism called galactosemia, resulting in elevations of galactose in the blood. Lactose Intolerance bonds with the C4 in glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance, a β-1,4-glycosidic bond is formed. Maltose is made up of 2 glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance molecules. The anomeric carbon in glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance (C1) is the α configuration (the hydroxyl group points down); therefore, the bond in maltose is an α-1,4-glycosidic bond between 2 glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance molecules.

        Image by Lecturio.

        Digestion of Carbohydrates

        Carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates are primarily digested by amylases and brush border Brush border Tubular System enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes. Carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates can only be absorbed as monosaccharides Monosaccharides Single chain carbohydrates that are the most basic units of carbohydrates. They are typically colorless crystalline substances with a sweet taste and have the same general formula CNH2NON. Basics of Carbohydrates, so these enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes break large starch molecules all the way down into single monosaccharides Monosaccharides Single chain carbohydrates that are the most basic units of carbohydrates. They are typically colorless crystalline substances with a sweet taste and have the same general formula CNH2NON. Basics of Carbohydrates.

        Note: Many dietary carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates are in the form of starch, which is a mixture of amylose and amylopectin (both are made entirely of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance molecules): 

        • Amylose is a straight chain of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance molecules joined with α-1,4-glycosidic bonds. 
        • Amylopectin includes numerous branches formed by α-1,6-glycosidic bonds.

        Amylases

        • Cleave α-1,4 glycosidic bonds between sugar molecules
        • Create smaller and smaller polysaccharide chains until most α-1,4 glycosidic bonds are broken leaving:
          • Monosaccharides Monosaccharides Single chain carbohydrates that are the most basic units of carbohydrates. They are typically colorless crystalline substances with a sweet taste and have the same general formula CNH2NON. Basics of Carbohydrates
          • Disaccharides Disaccharides Oligosaccharides containing two monosaccharide units linked by a glycosidic bond. Basics of Carbohydrates
          • Oligosaccharides Oligosaccharides Carbohydrates consisting of between two (disaccharides) and ten monosaccharides connected by either an alpha- or beta-glycosidic link. They are found throughout nature in both the free and bound form. Basics of Carbohydrates
          • Indigestible starches (sugars joined by other types of bonds)
        • Active at higher pH pH The quantitative measurement of the acidity or basicity of a solution. Acid-Base Balance:
          • Active in the mouth and small intestines
          • Inactivated in the stomach Stomach The stomach is a muscular sac in the upper left portion of the abdomen that plays a critical role in digestion. The stomach develops from the foregut and connects the esophagus with the duodenum. Structurally, the stomach is C-shaped and forms a greater and lesser curvature and is divided grossly into regions: the cardia, fundus, body, and pylorus. Stomach: Anatomy
        • Types and location of amylase Amylase A group of amylolytic enzymes that cleave starch, glycogen, and related alpha-1, 4-glucans. Digestion and Absorption:
          • Salivary amylase Amylase A group of amylolytic enzymes that cleave starch, glycogen, and related alpha-1, 4-glucans. Digestion and Absorption: secreted in the mouth by salivary glands Salivary glands The salivary glands are exocrine glands positioned in and around the oral cavity. These glands are responsible for secreting saliva into the mouth, which aids in digestion. There are 3 major paired salivary glands: the sublingual, submandibular, and parotid glands. Salivary Glands: Anatomy
          • Pancreatic amylase Pancreatic Amylase A group of amylolytic enzymes that cleave starch, glycogen, and related alpha-1, 4-glucans. Pancreatic Parameters: secreted into the duodenum Duodenum The shortest and widest portion of the small intestine adjacent to the pylorus of the stomach. It is named for having the length equal to about the width of 12 fingers. Small Intestine: Anatomy by the exocrine pancreas Exocrine pancreas The major component (about 80%) of the pancreas composed of acinar functional units of tubular and spherical cells. The acinar cells synthesize and secrete several digestive enzymes such as trypsinogen; lipase; amylase; and ribonuclease. Secretion from the exocrine pancreas drains into the pancreatic ductal system and empties into the duodenum. Pancreas: Anatomy
        Amylopectin is partially digested by amylase

        Amylopectin is partially digested by amylase Amylase A group of amylolytic enzymes that cleave starch, glycogen, and related alpha-1, 4-glucans. Digestion and Absorption. Amylopectin molecules are chains of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance, joined together by α-1,4-glycosidic bonds (create a straight chain of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance molecules) and α-1,6-glycosidic bonds (create a branch off the straight chain). Amylase Amylase A group of amylolytic enzymes that cleave starch, glycogen, and related alpha-1, 4-glucans. Digestion and Absorption breaks the α-1,4-glycosidic bonds.

        Image by Lecturio.

        Brush border Brush border Tubular System enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes

        Brush border Brush border Tubular System enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes are membrane-bound proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis on the luminal surface of enterocytes in the small intestine Small intestine The small intestine is the longest part of the GI tract, extending from the pyloric orifice of the stomach to the ileocecal junction. The small intestine is the major organ responsible for chemical digestion and absorption of nutrients. It is divided into 3 segments: the duodenum, the jejunum, and the ileum. Small Intestine: Anatomy. There are 4 major brush-border enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes involved in carbohydrate digestion Digestion Digestion refers to the process of the mechanical and chemical breakdown of food into smaller particles, which can then be absorbed and utilized by the body. Digestion and Absorption.

        • Isomaltase: cleaves α-1,6-glycosidic bonds 
        • Maltase: 
          • Splits maltose → glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance + glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance
          • Splits maltotriose → glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance + glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance + glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance
        • Lactase: splits lactose → glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance + galactose Galactose An aldohexose that occurs naturally in the d-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase causes an error in galactose metabolism called galactosemia, resulting in elevations of galactose in the blood. Lactose Intolerance
        • Sucrase: 
          • Splits sucrose → glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance + fructose
          • Splits other small oligosaccharides Oligosaccharides Carbohydrates consisting of between two (disaccharides) and ten monosaccharides connected by either an alpha- or beta-glycosidic link. They are found throughout nature in both the free and bound form. Basics of Carbohydrates

        Absorption of Carbohydrates

        After digestion Digestion Digestion refers to the process of the mechanical and chemical breakdown of food into smaller particles, which can then be absorbed and utilized by the body. Digestion and Absorption, carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates are absorbed and transported via the blood to the portal circulation Portal circulation A system of vessels in which blood, after passing through one capillary bed, is conveyed through a second set of capillaries before it returns to the systemic circulation. It pertains especially to the hepatic portal system. Systemic and Special Circulations. Transport may be either an active, facilitated, or passive mechanism.  

        • Active transport Active transport The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy. The Cell: Cell Membrane involves the use of transporter enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes, which uses energy to move carbohydrates Carbohydrates A class of organic compounds composed of carbon, hydrogen, and oxygen in a ratio of cn(H2O)n. The largest class of organic compounds, including starch; glycogen; cellulose; polysaccharides; and simple monosaccharides. Basics of Carbohydrates across the plasma membrane Plasma membrane A cell membrane (also known as the plasma membrane or plasmalemma) is a biological membrane that separates the cell contents from the outside environment. A cell membrane is composed of a phospholipid bilayer and proteins that function to protect cellular DNA and mediate the exchange of ions and molecules. The Cell: Cell Membrane even against the concentration gradient.
        • Facilitated diffusion Diffusion The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially facilitated diffusion, is a major mechanism of biological transport. Peritoneal Dialysis and Hemodialysis occurs down concentration gradients with the additional aid of transmembrane enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes that do not require energy.
        • Passive absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption moves sugars down concentration gradients without enzymatic assistance or energy needed; it is the slowest mechanism.

        Transporters have specific roles, and their functions may be active, facilitated, or passive.

        • Sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia–glucose-linked transporter 1 (SGLT1):
          • Found in the luminal membrane of enterocytes in the small intestine Small intestine The small intestine is the longest part of the GI tract, extending from the pyloric orifice of the stomach to the ileocecal junction. The small intestine is the major organ responsible for chemical digestion and absorption of nutrients. It is divided into 3 segments: the duodenum, the jejunum, and the ileum. Small Intestine: Anatomy
          • Functions to transport glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance and galactose Galactose An aldohexose that occurs naturally in the d-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase causes an error in galactose metabolism called galactosemia, resulting in elevations of galactose in the blood. Lactose Intolerance into the enterocytes
          • Relies on an actively generated sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia gradient generated by a Na+/K+-ATPase
          • Transports 2 sodiums, 1 glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance or galactose Galactose An aldohexose that occurs naturally in the d-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase causes an error in galactose metabolism called galactosemia, resulting in elevations of galactose in the blood. Lactose Intolerance, and water 
        • Glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance transporter 2 ( GLUT2 GLUT2 A glucose transport facilitator that is expressed primarily in pancreatic beta cells; liver; and kidneys. It may function as a glucose sensor to regulate insulin release and glucose homeostasis. Digestion and Absorption)  
          • Found in kidney, liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy, and pancreas Pancreas The pancreas lies mostly posterior to the stomach and extends across the posterior abdominal wall from the duodenum on the right to the spleen on the left. This organ has both exocrine and endocrine tissue. Pancreas: Anatomy and on the basolateral membrane of enterocytes in the small intestine Small intestine The small intestine is the longest part of the GI tract, extending from the pyloric orifice of the stomach to the ileocecal junction. The small intestine is the major organ responsible for chemical digestion and absorption of nutrients. It is divided into 3 segments: the duodenum, the jejunum, and the ileum. Small Intestine: Anatomy
          • Transports all 3 primary monosaccharides Monosaccharides Single chain carbohydrates that are the most basic units of carbohydrates. They are typically colorless crystalline substances with a sweet taste and have the same general formula CNH2NON. Basics of Carbohydrates ( glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance, galactose Galactose An aldohexose that occurs naturally in the d-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase causes an error in galactose metabolism called galactosemia, resulting in elevations of galactose in the blood. Lactose Intolerance, and fructose) via facilitated diffusion Diffusion The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially facilitated diffusion, is a major mechanism of biological transport. Peritoneal Dialysis and Hemodialysis 
          • With regard to absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption: GLUT2 GLUT2 A glucose transport facilitator that is expressed primarily in pancreatic beta cells; liver; and kidneys. It may function as a glucose sensor to regulate insulin release and glucose homeostasis. Digestion and Absorption moves monosaccharides Monosaccharides Single chain carbohydrates that are the most basic units of carbohydrates. They are typically colorless crystalline substances with a sweet taste and have the same general formula CNH2NON. Basics of Carbohydrates out of the enterocytes and into the interstitial space. 
          • Bidirectionality allows for a change in function depending on cellular conditions.
        • GLUT5 GLUT5 A hexose transporter that mediates fructose transport in skeletal muscle and adipocytes and is responsible for luminal uptake of dietary fructose in the small intestine. Digestion and Absorption 
          • Transports fructose via facilitated diffusions

        Passive glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption represents a minority of absorptive capabilities. Most absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption occurs in the 1st part of the small intestine Small intestine The small intestine is the longest part of the GI tract, extending from the pyloric orifice of the stomach to the ileocecal junction. The small intestine is the major organ responsible for chemical digestion and absorption of nutrients. It is divided into 3 segments: the duodenum, the jejunum, and the ileum. Small Intestine: Anatomy ( duodenum Duodenum The shortest and widest portion of the small intestine adjacent to the pylorus of the stomach. It is named for having the length equal to about the width of 12 fingers. Small Intestine: Anatomy, jejunum Jejunum The middle portion of the small intestine, between duodenum and ileum. It represents about 2/5 of the remaining portion of the small intestine below duodenum. Small Intestine: Anatomy).

        Order of events in monosaccharide absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption:

        1. Absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption into the enterocytes across the apical membrane: 
          • Glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance and galactose Galactose An aldohexose that occurs naturally in the d-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase causes an error in galactose metabolism called galactosemia, resulting in elevations of galactose in the blood. Lactose Intolerance: via SGLT1
          • Fructose: via GLUT5 GLUT5 A hexose transporter that mediates fructose transport in skeletal muscle and adipocytes and is responsible for luminal uptake of dietary fructose in the small intestine. Digestion and Absorption
        2. Release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology into the interstitial space through GLUT2 GLUT2 A glucose transport facilitator that is expressed primarily in pancreatic beta cells; liver; and kidneys. It may function as a glucose sensor to regulate insulin release and glucose homeostasis. Digestion and Absorption on the basolateral membrane via facilitated diffusion Diffusion The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially facilitated diffusion, is a major mechanism of biological transport. Peritoneal Dialysis and Hemodialysis
        3. Absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption into capillaries Capillaries Capillaries are the primary structures in the circulatory system that allow the exchange of gas, nutrients, and other materials between the blood and the extracellular fluid (ECF). Capillaries are the smallest of the blood vessels. Because a capillary diameter is so small, only 1 RBC may pass through at a time. Capillaries: Histology from the interstitial space
        4. Capillaries Capillaries Capillaries are the primary structures in the circulatory system that allow the exchange of gas, nutrients, and other materials between the blood and the extracellular fluid (ECF). Capillaries are the smallest of the blood vessels. Because a capillary diameter is so small, only 1 RBC may pass through at a time. Capillaries: Histology drain into veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology portal vein Portal vein A short thick vein formed by union of the superior mesenteric vein and the splenic vein. Liver: Anatomy liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy for metabolism
        Absorption monosaccharides

        Absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption of monosaccharides Monosaccharides Single chain carbohydrates that are the most basic units of carbohydrates. They are typically colorless crystalline substances with a sweet taste and have the same general formula CNH2NON. Basics of Carbohydrates across enterocytes
        SGLT1: sodium Sodium A member of the alkali group of metals. It has the atomic symbol na, atomic number 11, and atomic weight 23. Hyponatremia–glucose-linked transporter
        GLUT5 GLUT5 A hexose transporter that mediates fructose transport in skeletal muscle and adipocytes and is responsible for luminal uptake of dietary fructose in the small intestine. Digestion and Absorption: glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance transporter 5
        GLUT2 GLUT2 A glucose transport facilitator that is expressed primarily in pancreatic beta cells; liver; and kidneys. It may function as a glucose sensor to regulate insulin release and glucose homeostasis. Digestion and Absorption: glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance transporter 2

        Image by Lecturio.

        Monosaccharide Transport Within the Body

        Once in the blood, monosaccharides Monosaccharides Single chain carbohydrates that are the most basic units of carbohydrates. They are typically colorless crystalline substances with a sweet taste and have the same general formula CNH2NON. Basics of Carbohydrates are transported to cells throughout the body and absorbed into peripheral cells by a number of different transporters. Several important glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance transporters include:

        • GLUT4:
          • Most important glucose-uptake transporter
          • Expressed the most in skeletal muscle and adipose tissue Adipose tissue Adipose tissue is a specialized type of connective tissue that has both structural and highly complex metabolic functions, including energy storage, glucose homeostasis, and a multitude of endocrine capabilities. There are three types of adipose tissue, white adipose tissue, brown adipose tissue, and beige or “brite” adipose tissue, which is a transitional form. Adipose Tissue: Histology
          • Stimulated by insulin Insulin Insulin is a peptide hormone that is produced by the beta cells of the pancreas. Insulin plays a role in metabolic functions such as glucose uptake, glycolysis, glycogenesis, lipogenesis, and protein synthesis. Exogenous insulin may be needed for individuals with diabetes mellitus, in whom there is a deficiency in endogenous insulin or increased insulin resistance. Insulin to move circulating glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance into cells for use and/or storage
        • SGLT2:
          • Located in the proximal convoluted tubule Proximal convoluted tubule The renal tubule portion that extends from the bowman capsule in the kidney cortex into the kidney medulla. The proximal tubule consists of a convoluted proximal segment in the cortex, and a distal straight segment descending into the medulla where it forms the u-shaped loop of henle. Osmotic Diuretics ( PCT PCT The renal tubule portion that extends from the bowman capsule in the kidney cortex into the kidney medulla. The proximal tubule consists of a convoluted proximal segment in the cortex, and a distal straight segment descending into the medulla where it forms the u-shaped loop of henle. Osmotic Diuretics) in the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy
          • Responsible for > 90% of filtered glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance reabsorption
        Table: Review of transporters
        Transporter Location Function
        GLUT1 Most human cells: RBC, CNS, cornea Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium. It serves as the first refracting medium of the eye. Eye: Anatomy, placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity, fetal tissue
        • Controls glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption into the CNS across the blood– brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification barrier
        • Basal glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance uptake in all cells
        • High affinity for glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance
        GLUT2 GLUT2 A glucose transport facilitator that is expressed primarily in pancreatic beta cells; liver; and kidneys. It may function as a glucose sensor to regulate insulin release and glucose homeostasis. Digestion and Absorption
        • Small intestines: basolateral membrane of enterocytes
        • Liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy: hepatocytes Hepatocytes The main structural component of the liver. They are specialized epithelial cells that are organized into interconnected plates called lobules. Liver: Anatomy
        • Pancreatic β-islet cells
        • Kidney and small intestines
        • Transports monosaccharides Monosaccharides Single chain carbohydrates that are the most basic units of carbohydrates. They are typically colorless crystalline substances with a sweet taste and have the same general formula CNH2NON. Basics of Carbohydrates from basolateral membrane of enterocytes into the blood
        • Allows hepatocytes Hepatocytes The main structural component of the liver. They are specialized epithelial cells that are organized into interconnected plates called lobules. Liver: Anatomy to take up and release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance for glycolysis Glycolysis Glycolysis is a central metabolic pathway responsible for the breakdown of glucose and plays a vital role in generating free energy for the cell and metabolites for further oxidative degradation. Glucose primarily becomes available in the blood as a result of glycogen breakdown or from its synthesis from noncarbohydrate precursors (gluconeogenesis) and is imported into cells by specific transport proteins. Glycolysis and gluconeogenesis Gluconeogenesis Gluconeogenesis is the process of making glucose from noncarbohydrate precursors. This metabolic pathway is more than just a reversal of glycolysis. Gluconeogenesis provides the body with glucose not obtained from food, such as during a fasting period. The production of glucose is critical for organs and cells that cannot use fat for fuel. Gluconeogenesis
        GLUT3
        • Most human cells
        • CNS
        • Placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity
        • Transports glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance across the blood– brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification barrier, even in times of relative hypoglycemia Hypoglycemia Hypoglycemia is an emergency condition defined as a serum glucose level ≤ 70 mg/dL (≤ 3.9 mmol/L) in diabetic patients. In nondiabetic patients, there is no specific or defined limit for normal serum glucose levels, and hypoglycemia is defined mainly by its clinical features. Hypoglycemia
        • High affinity for glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance
        GLUT4
        • Adipose tissue Adipose tissue Adipose tissue is a specialized type of connective tissue that has both structural and highly complex metabolic functions, including energy storage, glucose homeostasis, and a multitude of endocrine capabilities. There are three types of adipose tissue, white adipose tissue, brown adipose tissue, and beige or “brite” adipose tissue, which is a transitional form. Adipose Tissue: Histology
        • Muscle tissue
        • Regulates glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance homeostasis Homeostasis The processes whereby the internal environment of an organism tends to remain balanced and stable. Cell Injury and Death
        • Stimulated by insulin Insulin Insulin is a peptide hormone that is produced by the beta cells of the pancreas. Insulin plays a role in metabolic functions such as glucose uptake, glycolysis, glycogenesis, lipogenesis, and protein synthesis. Exogenous insulin may be needed for individuals with diabetes mellitus, in whom there is a deficiency in endogenous insulin or increased insulin resistance. Insulin: controlled glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance uptake and storage
        • Induced by physical exercise
        GLUT5 GLUT5 A hexose transporter that mediates fructose transport in skeletal muscle and adipocytes and is responsible for luminal uptake of dietary fructose in the small intestine. Digestion and Absorption
        • Enterocytes
        • Spermatocytes
        Transports fructose
        SGLT1 Apical membrane of enterocytes in small intestines Absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance and galactose Galactose An aldohexose that occurs naturally in the d-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase causes an error in galactose metabolism called galactosemia, resulting in elevations of galactose in the blood. Lactose Intolerance from the gut lumen into enterocytes
        SGLT2 Proximal convoluted tubule Proximal convoluted tubule The renal tubule portion that extends from the bowman capsule in the kidney cortex into the kidney medulla. The proximal tubule consists of a convoluted proximal segment in the cortex, and a distal straight segment descending into the medulla where it forms the u-shaped loop of henle. Osmotic Diuretics
        • High-affinity, low-capacity transport proteins Transport proteins Proteins and Peptides
        • Responsible for > 90% of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance reabsorption

        Clinical Relevance

        • Lactose intolerance Lactose intolerance Lactose intolerance (LI) describes a constellation of symptoms due to lactase deficiency (LD), the enzyme located in the brush border of the absorptive cells in the small intestine. Lactose is the disaccharide present in milk and requires hydrolysis by lactase to break it down into its 2 absorbable constituents, glucose and galactose. Lactose intolerance typically presents with bloating, abdominal cramping, diarrhea, and flatulence. Lactose Intolerance: malabsorptive GI disorder caused by a deficiency in lactase, a brush border Brush border Tubular System enzyme involved in the digestion Digestion Digestion refers to the process of the mechanical and chemical breakdown of food into smaller particles, which can then be absorbed and utilized by the body. Digestion and Absorption and absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption of lactose. Lactose is a disaccharide composed of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance and galactose Galactose An aldohexose that occurs naturally in the d-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase causes an error in galactose metabolism called galactosemia, resulting in elevations of galactose in the blood. Lactose Intolerance. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with lactose intolerance Lactose intolerance Lactose intolerance (LI) describes a constellation of symptoms due to lactase deficiency (LD), the enzyme located in the brush border of the absorptive cells in the small intestine. Lactose is the disaccharide present in milk and requires hydrolysis by lactase to break it down into its 2 absorbable constituents, glucose and galactose. Lactose intolerance typically presents with bloating, abdominal cramping, diarrhea, and flatulence. Lactose Intolerance present with abdominal pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways, diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea, and flatulence after consuming lactose products. Treatment is dietary modification or lactase supplementation in milder cases.
        • Galactosemia Galactosemia Galactosemia is a disorder caused by defects in galactose metabolism. Galactosemia is an inherited, autosomal-recessive condition, which results in inadequate galactose processing and high blood levels of monosaccharide. The rare disorder often presents in infants with symptoms of lethargy, nausea, vomiting, diarrhea, and jaundice. Galactosemia: autosomal recessive Autosomal recessive Autosomal inheritance, both dominant and recessive, refers to the transmission of genes from the 22 autosomal chromosomes. Autosomal recessive diseases are only expressed when 2 copies of the recessive allele are inherited. Autosomal Recessive and Autosomal Dominant Inheritance condition that prevents galactose Galactose An aldohexose that occurs naturally in the d-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase causes an error in galactose metabolism called galactosemia, resulting in elevations of galactose in the blood. Lactose Intolerance processing due to a deficiency in 1 of 3 key enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes, the most common is galactose-1-phosphate uridylyltransferase. Galactosemia Galactosemia Galactosemia is a disorder caused by defects in galactose metabolism. Galactosemia is an inherited, autosomal-recessive condition, which results in inadequate galactose processing and high blood levels of monosaccharide. The rare disorder often presents in infants with symptoms of lethargy, nausea, vomiting, diarrhea, and jaundice. Galactosemia is a serious condition that presents early in life in infants, who experience lethargy Lethargy A general state of sluggishness, listless, or uninterested, with being tired, and having difficulty concentrating and doing simple tasks. It may be related to depression or drug addiction. Hyponatremia, nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics, vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia, diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea, and jaundice Jaundice Jaundice is the abnormal yellowing of the skin and/or sclera caused by the accumulation of bilirubin. Hyperbilirubinemia is caused by either an increase in bilirubin production or a decrease in the hepatic uptake, conjugation, or excretion of bilirubin. Jaundice. Later manifestations can include neurodevelopmental symptoms, cataracts, growth delay, and premature Premature Childbirth before 37 weeks of pregnancy (259 days from the first day of the mother’s last menstrual period, or 245 days after fertilization). Necrotizing Enterocolitis ovarian insufficiency. Treatment is dietary modification.
        • Diabetes mellitus Diabetes mellitus Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus: metabolic condition caused by chronic hyperglycemia Hyperglycemia Abnormally high blood glucose level. Diabetes Mellitus. Diabetes mellitus Diabetes mellitus Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus is due to deficiency in or resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing to insulin Insulin Insulin is a peptide hormone that is produced by the beta cells of the pancreas. Insulin plays a role in metabolic functions such as glucose uptake, glycolysis, glycogenesis, lipogenesis, and protein synthesis. Exogenous insulin may be needed for individuals with diabetes mellitus, in whom there is a deficiency in endogenous insulin or increased insulin resistance. Insulin. GLUT4 transporters are insulin-sensitive and help promote the storage of glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance under certain conditions. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with type 2 Type 2 Spinal Muscular Atrophy diabetes mellitus Diabetes mellitus Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus have a disruption in their response to insulin Insulin Insulin is a peptide hormone that is produced by the beta cells of the pancreas. Insulin plays a role in metabolic functions such as glucose uptake, glycolysis, glycogenesis, lipogenesis, and protein synthesis. Exogenous insulin may be needed for individuals with diabetes mellitus, in whom there is a deficiency in endogenous insulin or increased insulin resistance. Insulin and thus glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance accumulates in the blood, causing the chronic hyperglycemia Hyperglycemia Abnormally high blood glucose level. Diabetes Mellitus. Symptoms include urinary frequency, increased thirst, and increased appetite. Serious complications of diabetes mellitus Diabetes mellitus Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus include diabetic ketoacidosis Diabetic ketoacidosis A life-threatening complication of diabetes mellitus, primarily of type 1 diabetes mellitus with severe insulin deficiency and extreme hyperglycemia. It is characterized by ketosis; dehydration; and depressed consciousness leading to coma. Hyperglycemic Crises, cardiovascular disease, neuropathy Neuropathy Leprosy, and kidney disease.

        References

        1. Barrett, K.E., Barman, S.M., Brooks, H.L., Yuan, J.X. (2019). Digestion & absorption of nutrients. Chapter 26 of Ganong’s Review of Medical Physiology, 26th ed. New York: McGraw-Hill Education. Retrieved June 25, 2021, from https://accessmedicine.mhmedical.com/content.aspx?bookid=2525&sectionid=204296544
        2. Holesh, J.E., Aslam, S., Martin, A. (2021). Physiology, carbohydrates. StatPearls. Retrieved June 25, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK459280/
        3. Goodman, B.E. (2010). Insights into digestion and absorption of major nutrients in humans. Advances in Physiology Education 34(2):44–53. https://pubmed.ncbi.nlm.nih.gov/20522896/

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