Nutrient Procurement and Processing (3 of 3)
Content Standard Content Standard
The learners demonstrate an understanding of plant and animal organ systems for nutrient procurement and processing and their functions.
Performance Standard Performance Standard The learners shall be able to
• enumerate the structures or organs involved in nutrient procurement and processing in plants and animals;
• describe the functions of structures or organs involved in nutrient procurement and processing; and
• explain how food is processed in a mammalian digestive system Learning Competency
Learning Competency
The learners shall be able to compare and contrast nutrient procurement and processing in plants and animals.STEM_BIO11/12-IVa-h-1STEM_BIO11/12-IVa-h-1
Specific Learning Outcomes Specific Learning Outcomes
At the end of the lesson, the learners will be able to:
• enumerate and describe the main stages of food processing;
• describe the organs involved in food processing in the human digestive system and their roles;
• summarize the mechanisms of digestion, absorption, and delivery of nutrients into cells;
• explain the regulation of digestion; and
• cite some health problems associated with the digestive system.
60 MINS 60 MINS
LESSON OUTLINE Introduction
IntroductionCommunicating Learning Objectives 2 Motivation
Motivation The Digestive System 3
Instruction
Instruction Lecture on the Digestive System 30 Practice
Practice Drawing Activity or Laboratory Work 15 Enrichment
Microscopes and slides of a vertebrate small intestine cross-section. In the absence of microscopes and slides, visual aids of the mentioned specimen may be used.
Resources Resources
(1) Barrion AA, Tudor MFVA, Colle MCD, Reamillo MCS, and MAP Robles.
2000. BIOLOGY II Laboratory Manual: An Investigative Approach.
Institute of Biological Sciences, College of Arts and Sciences, UP Los Baños.
(2) Brooker RJ, Widmaier EP, Graham LE, Stiling PD. 2008.Biology. Boston:
McGraw- Hill. 1300 pp.
(3) Johnson GB and PH Raven.1996. BIOLOGY: Principles and Explorations.Austin, USA: Holt, Rinehart and Winston. 1072p.
(4) Reece JB, Urry LA, ,Wasserman SA, Minorsky PV, Jackson RB. 2011.
Campbell Biology (10th Edition). US: Benjamin Cummings. 1488 pp.
(5) Starr C and R Taggart. 2004. BIOLOGY: The Unity and Diversity of Life.
Tenth Edition. Australia: Thomson – Brooks/Cole. 933p.
INTRODUCTION (2 MINS) Communicating Learning Objectives Communicating Learning Objectives
1. Present the topic outline for Nutrient Procurement and Processing. An example is given below:
I. Plant Nutrition
A. Nutritional requirements of plants
B. Routes for absorption of water and minerals across the roots C. Nutritional adaptations by plants
II. Animal Nutrition
A. Nutritional requirements of animals B. Food uptake in cells
C. Variations in feeding mechanisms and digestive compartments in animals III. The Human Digestive System
2. Cite the Specific Learning Outcomes for this topic.
MOTIVATION (3 MINS) The Digestive System The Digestive System
1. The usual way of presenting food processing in the human digestive system is to follow the fate of food as it passes from mouth to anus.
2. A figure or diagram of the human digestive system may be presented to class as an overview of the components and processes of the digestive system.
3. Demonstrate peristalsis by placing a ball inside a stocking and squeezing to move it along.
INSTRUCTION (30 MINS) Lecture on the
Lecture on the Digestive SystemDigestive System
1. Enumerate and describe the main stages of food processing:
A. IngestionIngestion– the act of eating or feeding; this is coupled with the mechanical breakdown of food into smaller pieces allowing for a greater surface area for chemical digestion.
B. DigestionDigestion– breakdown of food into particles, then into nutrient molecules small enough
Teacher Tip Teacher Tip
The topic on Nutrient Procurement and Processing can be divided into three parts, with one-hour session being allotted for each part.
Part I. Plant Nutrition (1 hour) Part II. Animal Nutrition (1 hour) Part III. The Human Digestive System (1 hour)
Teacher tip Teacher tip
You may assign the students to bring food or snackpacked in foil or plastic that shows a table on Nutrition Facts.
The different kinds of nutrients listed in the Nutrition Facts table are among the nutritional requirements of animals.
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to be Chemical digestion by enzymes involves breaking of chemical bonds through the addition of water, i.e., enzymatic hydrolysis.
C. Absorption Absorption– passage of digested nutrients and fluid across the tube wall and into the body fluids; the cells take up (absorb) small molecules such as amino acids and simple sugars.
D. EliminationElimination–expulsion of the undigested and unabsorbed materials from the end of the gut.
2. Describe the organs involved in food processing in the human digestive system:
A. The Oral Cavity, Pharynx, and EsophagusThe Oral Cavity, Pharynx, and Esophagus
I. Oral CavityOral Cavity – it is where food is initially chewed into shreds by the teeth, and mixed with saliva by the tongue. Saliva is secreted into the mouth by three pairs of salivary glands located above the upper jaw and below the lower jaw.
II. Pharynx Pharynx –the region in the back of the throat that serves as the entrance to the esophagus that connects to the stomach and trachea (windpipe) that serves as airway to the lungs. To block breathing as food leaves the pharynx, a flap-like valve (the epiglottis) and the vocal cords close off the trachea.
III. EsophagusEsophagus – connects the pharynx with the stomach. No digestion takes place within the esophagus but the contractions within its muscular wall propel the food past a sphincter, into the stomach. The rhythmic waves of contraction of the smooth muscle wall of the esophagus are called peristaltic contractions or peristalsis. The esophagus is about 25 cm (10 in.) long.
B. The StomachThe Stomach
I. The stomachstomachis a muscular, stretchable sac located just below the diaphragm. It has three important functions. First, it mixes and stores ingested food. Second, it secretes gastric juice that helps dissolve and degrade the food, particularly proteins. Third, it regulates the passage of food into the small intestine.
II. The gastric juicegastric juiceis a combination of HCl and acid-stable proteases.
III. The churning action of the stomach together with the potent acidity of the gastric juice convert food into a thick, liquid mixture called chyme.
Note to the Teacher
The lecture for this part is quite long; some details may be omitted in the delivery. A handout on the lecture may be given to the students so that time may be devoted to listening to the teacher instead of copying the lecture.
Teacher Tips:
Regardless of the variations in the structures of a complete digestive system (eg.digestive system of a toad versus that of a bird), there are four distinct stages of food processing that are carried out.
These are: ingestion, digestion, absorption, and elimination.
Saliva has several components. It contains an enzyme (salivary amylase), a buffer ( bicarbonate), slippery glycoproteins (mucins), and antimicrobial agents such as lysozyme.
A sphincter is a ring of smooth muscles that close off a passageway or an opening to the body surface.
The stomach secretes about 2 L of HCl every day, rendering a very low pH in the stomach (between 1.5 and 2.5), about 3 million times more acidic than the bloodstream.
Ask the students to research on how the gastric juice can facilitate chemical digestion.
C. Small IntestineSmall Intestine
I. The small intestinesmall intestineis approximately 6 meters long and is composed of three regions:
the duodenum, jejunum, and ileum.
II. It is where most enzymatic hydrolysis of the macromolecules from food occurs. The complete digestion of carbohydrates, fats, and proteins occurs in the duodenum, about the first 25 cm. of the small intestine.
III. The rest of the small intestine is devoted to absorbing water and the products of digestion into the bloodstream.
IV. Absorption of the end products of digestion takes place in the ileum, the surface area of which is increased by villi and microvilli.
D. The Accessory Digestive OrgansThe Accessory Digestive Organs
I. Pancreas, Liver, and GallbladderPancreas, Liver, and Gallbladder – review the functions discussed in previous meeting.
E. The Large Intestine or ColonThe Large Intestine or Colon
I. The large intestinelarge intestineis much shorter than the small intestine, about 1 meter.
II. It concentrates and stores undigested matter by absorbing mineral ions and water. A small amount of fluid, sodium, and vitamin K are absorbed through its walls.
III. Unlike the small intestine, it does not coil up and does not have villi and has only one-thirtieth of the absorptive surface area of the small intestine.
IV. Many bacteria live and thrive within the large intestine where they help process undigested material into the final excretory product, feces.
F. The Rectum and AnusThe Rectum and Anus
I. The rectumrectumis a short extension of the large intestine and is the final segment of the digestive tract. It is where the compacted undigested food from the colon are pushed via peristaltic contractions.
II. The distention of the rectum triggers expulsion of feces.
III. The anusanusis the terminal opening of the digestive system through which feces are expelled.
Teacher Tip:
Teacher Tip:
The gut wall consists of four tissue layers surrounding a central cavity –the lumen. In contact with the lumen is the mucosa, followed by the submucosa, circular muscle layer, longitudinal muscle layer, and serosa.
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3. Summarize the mechanisms of digestion and absorption:
A. Carbohydrate digestion begins in the mouth but could not continue in the stomach due to the acidic pH that destroys the amylase. It resumes in the small intestine where the resulting monosaccharides are absorbed.
B. Proteins are digested in the stomach and small intestine. Resulting amino acids are absorbed in the small intestine where they leave the intestinal cell and enter the blood through a facilitated diffusion carrier in the plasma membranes on the opposite side.
C. Fat digestion occurs entirely in the small intestine. Although fatty acids and
monoglycerides enter epithelial cells from the intestinal lumen, it is triglycerides that are released on the other side of the cell and carried by blood capillaries to be transported throughout the body.
D. Most water-soluble vitamins are absorbed by diffusion or active transport. Fat-soluble vitamins follow the pathway for fat absorption.
4. Describe how nutrients are delivered into cells:
A. Substances pass through the brush border cells that line the free surface of each villus by active transport, osmosis, and diffusion across the lipid bilayer of plasma membranes.
B. The nutrients then proceed into the internal environment and pass to the blood which is collected into the hepatic portal vein leading to the liver.
C. After flowing through the liver, the blood carrying the nutrients passes into the hepatic vein which carries the blood back to the heart to be distributed to the different body tissues.
5. Explain the regulation of digestion:
A. The digestive system of animals is regulated in part by other organ systems, especially the nervous and endocrine systems.
B. The nervous system exerts control on the digestive system in two ways:
I. regulation of muscular and glandular activity by the local nerves in the alimentary canal; and
II. long-distance regulation by the brain.
C. Hormones regulate the rate of digestion.
Teacher Tip:
Teacher Tip:
Emphasize that digestion and absorption are inseparable in the total function of providing nutrition to body cells.
6. Cite some health problems associated with nutrition and digestive system:
A. Frequent complaints associated with the gastro-intestinal tract include heart burn, ulcers, and diarrhoea.
PRACTICE (20 MINS) Drawing Activity or Laboratory Work
1. As an alternative to a pure lecture discussion, questions related to the anatomy or function of each organ or component may be asked. As each digestive organ is discussed, reference to an overhead transparency or visual can be done.
2. For example: In relation to the oral cavity, ask the students what other structures or secretions may be found and cite the possible function of each in relation to digestion.
3. Sample answers: teeth, tongue, saliva – cite the functions of each; proceed to the succeeding parts of the digestive system
4. Ask the students to observe and draw a cross-section of the vertebrate small intestine (either from a microscopic slide viewed under scanner objective or a visual aid) and label the following components from the inner to outer layer:mucosa, submucosa, circular muscle layer, longitudinal muscle layer, and serosa.
5. If using a microscope to view the small intestine cross-section, shift to the low power objective (LPO) and focus on the infoldings of the mucosa which make up the villi. Draw and label.
6. Also present but could not be seen under an ordinary microscope are the numerous cytoplasmic extensions of the cells lining a villus, which are called microvilli. Keeping in mind the major functions of the small intestine, what is the significance of the presence of villi and microvilli?
ENRICHMENT (5 MINS) Conceptual Questions
1. Distinguish between digestion and absorption.
2. Give some reasons why dietary fiber which can come from fruits and vegetables, is so important in our diet.
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EVALUATION (5 MINS)
1. The pancreas connects to which part of the alimentary canal?
A. Esophagus B. Stomach C. Small intestine D. Cecum E. Large intestine
2. Which of the following statements regarding the vertebrate stomach is not correct?
A. Its cells secrete the protease enzyme pepsin.
B. It is a saclike organ that evolved to store food.
C. Its cells secrete hydrochloric acid.
D. It is the initial site of protein digestion.
E. Absorption of many nutrients occurs there.
3. Absorption in the small intestine is increased by :
A. The many villi that are present on the inner surface of the small intestine.
B. The brush border formed by microvilli on the cells of the villi.
C. The presence of numerous transporter proteins on the epithelial cells.
D. All of the above.
E. None of the above.
4. Which of the following is a function of the large intestine?
A. It participates in cellulose digestion by microbes that exist in the cecum of herbivores.
B. It stores and concentrates fecal material.
C. Its cells absorb salts and water that remain in chyme after it leaves the small intestine.
D. Its cells absorb certain vitamins.
E. All of the above.
5. Which of the following is correct?
A. Carbohydrate digestion starts in the mouth and resumes in the small intestine.
B. Protein digestion occurs only in the small intestine.
C. Fat digestion occurs in the stomach and small intestine.
D. Both water-soluble and fat-soluble vitamins are absorbed by diffusion or active transport.
E. All of the above.
Answer K Answer Key:ey:
1. C 2. E 3. D 4. E 5. A
The teacher may add more items to the quiz to be taken from the lecture material or books with end of chapter review questions.
Assignment Assignment
1. Enumerate the major digestive enzymes for carbohydrate, protein, fat, and nucleic acid digestion. Tabulate as follows:
ENZYME / SOURCE ORGAN / WHERE ACTIVE / SUBSTRATE / MAIN BREAKDOWN PRODUCTS
2. What contributes to the absorption capacity of the small intestine?
3. Why doesn’t gastric juice destroy the stomach cells that make it?
4. What are the cells making up the gastric glands of the stomach?
5. Describe the following ailments associated with the digestive system and identify their causes:
A. Gastric ulcers B. Acid reflux C. Heartburn
ASSESSMENT GUIDE
ASSESSMENT GUIDE (FOR THE ACTIVITY AND (FOR THE ACTIVITY AND LABORALABORATORY WORK NUTORY WORK NUMBERS 2 AND 3MBERS 2 AND 3 INVOLVING DRAWING LABELING)
INVOLVING DRAWING LABELING)
1.(POOR)(POOR)– disorganized drawing with many errors in the labeling of cell layers in the root cross sections and in the tracing of the apoplast and symplast routes.
2.(SATISFACTORY)(SATISFACTORY)– acceptable drawing with some errors in the labeling of cell layers in the root cross sections and in the tracing of the apoplast and symplast routes.
3.(VERY GOOD)(VERY GOOD)– clear drawing with minimal error in the labeling of cell layers in the root cross sections and in the tracing of the apoplast and symplast routes.
4.(EXCELLENT)(EXCELLENT)– clear drawing with correct labels for the cell layers in the root cross sections;
and accurate tracing of the apoplast and symplast routes.
ASSESSMENT GUIDE
ASSESSMENT GUIDE (FOR QUIZ AND ASSI(FOR QUIZ AND ASSIGNMENT): THE TEACHGNMENT): THE TEACHER MAER MAY ASSIGNY ASSIGN POINTS TO THE QUESTIONS
POINTS TO THE QUESTIONS 1.(POOR)(POOR)– 74% and below 2.(FAIR)(FAIR)– 75 TO 79% correct 3.(SATISFACTORY)(SATISFACTORY)– 80 to 84% correct
4.(VERY SATISFACTORY)(VERY SATISFACTORY)– 85 to 89% correct 5.(OUTSTANDING)(OUTSTANDING)– 90 to 100% correct
Note to the Teacher:
Note to the Teacher:
Answers to the assignment may be written on bond paper and submitted on the following meeting.
Answers to the assignment may be found in Reece et al., 2011; Starr and Taggart, 2004, and; any General Biology book.
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