Online Counseling Resource YCMOU ELearning Drive… School of Architecture, Science and Technology Yashwantrao Chavan Maharashtra Open University, Nashik – , India

OC-SEP033-CP01-01 Introduction Programmes and Courses  SEP – SBT033 – Unit 01  SEP – SBI033 – Unit 01  SEP – SGS033 – Unit 01

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.3 Credits  Academic Inputs by Arun Punaji More. M.Sc. (Microbiology) Experience: 11 Years. 

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.4 How to Use This Resource  Counselor at each study center should use this presentation to deliver lecture of minutes during Face-To-Face counseling.  Discussion about students difficulties or tutorial with assignments should follow the lecture for about minutes.  Handouts (with 6 slides on each A4 size page) of this presentation should be provided to each student.  Each student should discuss on the discussion forum all the terms which could not be understood. This will improve his writing skills and enhance knowledge level about topics, which shall be immensely useful for end exam.  Appear several times, for all the Self-Tests, available for this course.  Student can use handouts for last minutes preparation just before end exam.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.5 Learning Objectives  After studying this module, you should be able to: Describe digestion of carbohydrates. Describe various digestive end products of carbohydrates. Describe various digestive enzymes involve in digestion of carbohydrates. Explain the action of various digestive enzymes.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.6 Introduction-1  The carbohydrates are the main source of energy in mammals.  About 60% of energy requirements of the mammals is met by carbohydrates.  All the carbohydrates are first broken down into monosaccharides such as glucose, fructose before they are absorbed through digestive tracts.  Let’s see how the carbohydrates are digested by various enzymes in digestive tract.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.7 Introduction-2  Students will learn about the mechanism by which the digestive end products are absorbed through the digestive tract and about the various digestive end products of carbohydrates digestion.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.8 Digestion of Carbohydrates-1  The human diet includes three major sources of carbohydrates : Sucrose (disaccharide). Lactose (disaccharide). Starch (polysaccharide).  In digestion of sucrose, sucrose is hydrolyzed into fructose and glucose.  In digestion of lactose, lactose is hydrolyzed into glucose and galactose.  In digestion of starch, starch is first hydrolyzed into maltose and oligosaccharides.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.9 Digestion of Carbohydrates-2  Digestion of carbohydrates takes place in three different anatomical sites such as: Mouth. Stomach. Small intestine.  Digestion of carbohydrates in mouth: When food is chewed in mouth, carbohydrates are mixed with saliva and partially digested due to action of ptyalin, an α-amylase secreted by parotid gland. In mouth the carbohydrates are hydrolyzed by this enzyme into maltose and into small oligosaccharides of glucose.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.10 Digestion of Carbohydrates-3  Digestion of carbohydrates in mouth: Since the carbohydrates remain in mouth for very short time, only approximately 5% of starch is hydrolysed into maltose and small oligosaccharides of glucose.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.11 Digestion of Carbohydrates-4  Digestion of carbohydrates in stomach: In stomach the food is mixed with gastric juice. The action of α-amylase in saliva continue in stomach until it is thoroughly mixed with gastric juice making the content acidic inhibiting the action of α-amylase on carbohydrates; and bring about digestion of 40% of carbohydrates.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.12 Digestion of Carbohydrates-5  Digestion of carbohydrates in small intestine: In small intestine the enterocytes lining micro villi of small intestine secrete four enzymes:  Lactase.  Sucrase.  Maltase.  α-dextrinase. These enzymes hydrolyse the disaccharides into their corresponding monosaccharides.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.13 Digestion of Carbohydrates-6  Lactase hydrolyzes lactose into galactose and glucose.  Sucrase hydrolyzes sucrose into glucose and fructose.  Maltase hydrolyzes maltose into maltose into glucose.  Α-dextrinase hydrolyzes small polymers of glucose into glucose.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.14 Absorption of Monosaccharides-1  Absorption of glucose:- Glucose is absorbed by an active transport process. Glucose absorption requires sodium. Glucose absorption is coupled with the active transport of sodium ions into epithelium cells of small intestine. When concentration of sodium ions inside the epithelium cells decreases due to transport of sodium ions into blood, sodium ions in the intestinal lumen move into epithelium cells by the process of facilitated diffusion with the help of transport proteins.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.15 Facilitated Transport In this figure 1,2, and 3 are carrier proteins.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.16 Active Transport In this figure 1, 2, and 3 are carrier proteins.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.17 Absorption of Monosaccharides-2  Absorption of glucose:- In facilitated diffusion the transport proteins do not move into epithelium cells until they are combine some second molecule such as glucose which has ability to combine with the same transport proteins. Thus the glucose molecules are co- transported along with the sodium ions with the help of transport proteins into epithelium cells. The glucose molecules then move into the paracellular space through the epithelium cells' basolateral membrane and from paracellular space into blood.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.18 Absorption of Monosaccharides-3  Absorption of galactose also occurs by the sodium co- transport mechanism.  Fructose is also transported into epithelium cells by facilitated diffusion mechanism but not coupled with the sodium co-transport; therefore the rate of the fructose transport into the epithelium cells is half that of glucose.  Once inside the epithelium cells, fructose is phosphorylated and the converted to glucose which is then transported into blood as described above.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.19 What We Learn…..  The digestion of various carbohydrates such as starch, lactose and sucrose.  The enzymes involved in the digestion of above sugars.  The final products of carbohydrates digestion.  Absorption mechanism of various end products of carbohydrates digestion.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.20 Critical Thinking Question  Why highly dehydrated person is given glucose solution mixed with table salt?

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.21 Tips for Critical Thinking Question  Absorption mechanism of glucose.

School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.22 Study Tips  Book Title:Textbook of medical physiology. Dr. Arthur C. Guyton, John E. Hall. Author: Dr. Arthur C. Guyton, John E. Hall. Publication: Elsevier India Private Limited.  Book Human Physiology Title: Human Physiology C. C. Chattergy. Author: C. C. Chattergy.

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