BIO204L WEEK 6-7 MODULE.pdf
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College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City...
College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 Week 6-7: Unit Learning Outcomes (ULO): At the end of the unit, you are expected to a. relate the functions of chloroplast and mitochondria to energy production (photosynthesis and cellular respiration). b. discuss the anatomy and physiology of the Human Digestive System. Big Picture in Focus ULO-a. relate the functions of chloroplast and mitochondria to energy production (photosynthesis and cellular respiration). In this segment, the important terminologies related to the functions of chloroplast and mitochondria to the energy production (photosynthesis and cellular respiration), which were denoted in the ULO-a, will be operationally and theoretically defined to establish a collective understanding needed for the discussion of the topics. You will encounter these vocabularies as we go through the details of chloroplast and mitochondria's functions to energy production. Please refer to these definitions when you have difficulty in understanding some concepts. 1. Photosynthesis It is a synthesis process by which plants and other chlorophyll-containing organisms use the light energy to produce carbohydrates (sugars) from carbon dioxide and water that generates oxygen as a byproduct aid of Chloroplast. 2. Cellular Respiration It is a biological process that releases chemical energy from sugars and other carbon-based molecules to make ATP when oxygen is present. 3. ATP ATP stands for Adenosine Triphosphate. It is composed of the nitrogen base adenine, the pentose (5C) sugar, which is the ribose, and three phosphate groups. The last phosphate group is bonded with a high energy chemical bond that can be broken to release energy for cells to function. 4. Fermentation It is a product of a metabolic process that produces energy from the carbohydrates in the absence of oxygen. If oxygen is present, products of glycolysis are used in cellular respiration. Fermentation helps a cell make ATP by allowing glycolysis to continue. 71 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 5. Chlorophyll It is a pigment that absorbs red and blue light (photons). It reflected or transmitted the green and yellow solar spectra. 6. Biochemical Pathway Series of reactions where the product of one reaction is required and consumed in the next response. For instance, glucose, a product of photosynthesis, is used in cellular respiration to make ATP. 7. Chloroplast This is a double membrane organelle that absorbs light energy. This is the site where photosynthesis occurs. It contains the Thylakoids that contains the chlorophyll and the Stroma, the solution around thylakoids. 8. Phosphorylation A biochemical metabolism that adds the phosphate group to a carbon-based compound. 9. ATP Synthase It is a multifunctional carrier protein that harnesses the energy in the thylakoid membrane. It is also a specialized enzyme that catalyzes ATP. It is an enzyme that converts the potential power of protons into ATP's chemical energy across the thylakoid membrane. 10. Calvin Cycle A biochemical pathway in photosynthesis that produces organic compounds using ATP & NADPH. It also processes carbon fixation where carbon atoms from CO2 are bonded or ‘fixed’ into carbohydrates. In this portion, you will accomplish the Unit Learning Outcomes, which was stipulated in the Big Picture. This will be done for the sixth and seventh weeks of this course. Your understanding of the following concepts is essential to proceed with successive topics. You may refer to other available references to explore more on the subjects. Thus, you are expected to utilize other books, research articles, and other resources that are available in the university’s library, e.g., ebrary, search.proquest.com, etc. LECTURE AUTOTROPHS AND HETEROTROPHS One of the attributes of all organisms is to acquire nourishment. The word “troph” refers to the sustenance, food, and the procurement of the nourishment. The term is derived from the Greek word “trophos,” denotes being nourished or the one who feeds. 72 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 Autotrophs They are considered as the producer. They make their food and fix carbon. These organisms produce complex organic compounds such as the carbohydrates, fats, and proteins from simple inorganic molecules using the energy from light through photosynthesis or inorganic chemical reactions or chemosynthesis. Kinds of Autotrophs Phototrophs - These are mostly plants that use light as a source of energy. Chemoautotrophs - Bacteria or fungi that obtain their food by inorganic chemical reactions. Heterotrophs Organisms that obtain energy from organic molecules that are made by autotrophs. These organisms fail to synthesize their food and are dependent on the producers or other organisms to supply organic compounds required for their growth. Kinds of Heterotrophs: Herbivores - A heterotroph that obtains energy directly from plants. Carnivores - Those animals which feed on other animals. Omnivores - Animals that obtain their food from plants as well as from other animals. Saprobes - Organisms that obtain energy by breaking down remains of dead plants and animals. They are also called Detritivores that fed on detritus or decomposed matters. The diagram below is an overview of the cycle between autotrophs and heterotrophs. Photosynthesis is the principal means by which plants, algae, and many bacteria produce organic compounds and oxygen from carbon dioxide and water (green arrow). 73 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 PHOTOSYNTHESIS It is the production of carbohydrates (sugars) from carbon dioxide and water, using sunlight as the source of energy and chlorophyll. It is a conversion of light energy into chemical energy stored in organic compounds (carbohydrates or glucose). The synthesis process is used primarily by autotrophs such as the plants, algae, and some bacteria (prokaryotes). Chloroplasts are the organelles where photosynthesis takes place in plants. Most chloroplasts are in leaf cells. Two main parts of chloroplast needed for photosynthesis: Stroma – fluid surrounds the grana Grana – stack of thylakoids, contain chlorophyll 74 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 Steps of Photosynthesis 1. The chlorophyll in the cells of plants absorbs light from the sun. 2. The sun’s energy splits the water molecules into hydrogen and oxygen. 3. The hydrogen joins with carbon dioxide (CO2) to make sugar (food). 4. The sugar is carried to other parts of the plant. The extra oxygen is released into the air. LIGHT AND DARK REACTION PHASE Stage 1 – The Light-Dependent Reaction The light reaction phase captured energy from the sunlight. It takes place within the thylakoid membrane. The ultimate source of energy for all living things on Earth is the sun. The main form of energy from the sun is in the form of electromagnetic radiation. Visible radiation (white light) is used for photosynthesis. Chlorophyll is a pigment that absorbs red & blue light (photons), so green is reflected or transmitted. Chlorophyll is located in the thylakoid membranes. So, Plants are green because the green wavelength is revealed, not absorbed. The sun's energy is absorbed and used to split the water molecules and release the oxygen molecules into the environment. When the chlorophyll absorbs light, some of its electrons are raised to a higher energy level. The electromagnetic wavelengths and the wavelengths that are absorbed by the chlorophyll. This phase of photosynthesis takes place when there is a light source. In the natural world, this is in daylight. It takes the hydrogen from water, releases oxygen, changes the light energy into chemical energy, and makes glucose. 75 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 2 Types of Chlorophyll - Chlorophyll a – involved in light reactions - Chlorophyll b – assists in capturing light energy and considered as an accessory pigment - Carotenoids – accessory pigments that capture more light energy, the red, orange and yellow Stage 2 – The Light Independent Reaction or Calvin Cycle or the Dark Reaction Phase Light-independent reactions use energy from light-dependent results to make sugars. Its reactions take place in the stroma of chloroplasts. Carbon dioxide molecules are used to build sugar, and six-carbon simple sugar is produced. The sugars produced are often used to develop starches and cellulose. The two essential things to these reactions are the carbon dioxide and energy produced from the light-dependent results. The second phase of photosynthesis occurs after the sun goes down. It uses oxygen and glucose already made within the plant to create and release water and carbon dioxide. Depending on how much energy the plant has stored during the daytime, this process can continue through the night. 76 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 CELLULAR RESPIRATION It is the process in which organisms take molecules broken down from food and release the chemical energy stored in the chemical bonds of those molecules. It’s important to remember that food is not the direct source of energy. It is a biological process that releases chemical energy from sugar and other carbon-based molecules to make ATP when oxygen is present. The types of molecules that are broken down include any food (organic) molecule, or nutrients, such as the carbohydrates, fats/lipids, and proteins. They can be processed and broken down as sources of energy to produce ATP. ATP will release energy for cellular metabolic processes like active transport of molecules across the cell membrane, protein synthesis, and muscle contractions. The energy that is released from chemical bonds during cellular respiration is stored in molecules of ATP. Cellular respiration takes place in the mitochondria of the eukaryotic cell. Recall that the mitochondria are considered the “powerhouse” of the cell because it produces the majority of a cell’s ATP. Parts of the Mitochondria Many similarities exist between the chloroplast and the mitochondria. - It has a double membrane. - Mitochondria have their DNA and only come from preexisting mitochondria. - Mitochondria have a smooth outer membrane. - Mitochondria have a folded inner-membrane called the cristae. - A folded inner membrane allows more surface area for chemical reactions to occur. 77 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 - Mitochondria have a center called the matrix. Major Steps of Cellular Respiration 1. Glycolysis (anaerobic) 2. Krebs Cycle (aerobic) 3. Electron Transport Chain (aerobic) Energy Carriers Found in Cellular Respiration - ATP - NADH (similar to NADPH in photosynthesis) - FADH2 Glycolysis Glycolysis is an anaerobic step in the cellular respiration pathway; therefore, it doesn’t require oxygen. Glycolysis takes place in the cytoplasm of the cell and is a series of reactions using enzymes. It is a process of splitting of a molecule of glucose. The products of glycolysis are broken down in the mitochondria to make more ATP. When a molecule of glucose is split, pyruvic acid, NADH, and ATP are produced. Glycolysis makes four ATP molecules, but it takes two molecules of ATP for the reaction to occur. Therefore, glycolysis yields a net of 2 ATP molecules. Pyruvic acid production is the primary goal of glycolysis, and these molecules will move on to the Krebs Cycle: Pyruvic Acid, Krebs Cycle, NADH, ETC, ATP, and usable energy. 78 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 The Aerobic Pathway Pre-Krebs Cycle (Acetyl- CoA) Before pyruvic acid enters the Krebs Cycle, it combines with an enzyme called Coenzyme A (CoA). This reaction produces a molecule of Acetyl CoA. It is a molecule produced by almost all nutrients (carb., protein, lipids) before entering the Krebs Cycle. Krebs Cycle or the Citric Acid Cycle This cycle is named after Hans Krebs, who won the Nobel Prize for the pathway he discovered in cellular respiration. It is a cyclical series of oxidation reactions that give off CO2 and produce one ATP per cycle. It requires an oxygen molecule (Aerobic) and turns twice per glucose molecule that produces 1 ATP per turn, a total of two ATP for the whole process. This cycle takes place in the matrix of mitochondria. The Acetyl CoA that formed from Pyruvic Acid combines with a four-carbon molecule to make a molecule of citric acid. Citric acid is broken down in several steps, providing the energy to make NADH, FADH2, and ATP. 79 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 Krebs Cycle Reactant Summary Krebs Cycle Product Summary Pyruvic Acid 2 ATP Usable energy ADP NADH Goes to ETC NAD+ FADH2 Goes to ETC FAD+ CO2 Byproduct The Electron Transport Chain The ETC is a series of proteins located in the mitochondrial membrane. It uses high energy electrons from the NADH and FADH2, provided by the Krebs Cycle to move H+(protons) across the concentration gradient. These protons pass back down the concentration gradient through ATP synthase to form ATP. This is very much like the ETC in the light reactions of photosynthesis. Oxygen is used as the final electron acceptor at the end of the ETC. Oxygen receives electrons and H+(hydrogen ions) and produces a molecule of water. ETC Product Summary 34 ATP - Usable energy H2O - Byproduct 80 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 Overview of Aerobic Respiration Cellular Respiration ATP Tally 1. Glycolysis – 2 ATP 2. Krebs Cycle – 2 ATP 3. ETC – up to 34 ATP Grand Total = 36-38 ATP Anaerobic Pathways - Fermentation This process happens to the products of glycolysis when O2 is absent. Breathing provides enough oxygen for your body to carry out normal activities. When you conduct a high level of activity, breathing doesn’t supply enough air for your cell’s activities. If oxygen is not present, glycolysis products (pyruvic acid and NADH) will enter an alternative process called Fermentation. Fermentation provides enough ATP and recycles NADH into NAD+ so that glycolysis may continue until more oxygen becomes available. Where does Fermentation occur? The cytosol of the cell Two Types of Fermentation Lactic Acid Fermentation It is a process that occurs in muscle cells in the body. Lactic acid is a waste product of fermentation that will build up and cause your muscles to “burn” during laborious exercise. It 81 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 also occurs in some bacteria and molds. Waste products of the fermentation process give different cheese flavors. Yogurt is another product of lactic acid fermentation. Alcoholic Fermentation Alcoholic fermentation is a process used by many yeasts and plants. It also uses glycolysis products (NADH and pyruvic acid) to provide enough NAD+ and ATP for glycolysis to continue. It used to make bread or dough rise and is also used for beer and wine. Bacteria that rely upon fermentation play a significant role in the digestive systems of animals. They breakdown molecules by taking undigested material for their needs. Without these bacteria, we’d be unable to digest food fully. Performance Task/ Laboratory Activities (Instructions and procedures will be provided by the subject teacher.) Laboratory Activity # 9 Laboratory Activity # 10 You can also refer to the sources below to help you further understand the lesson: Mason, Kenneth A. (2017). Biology (11th edition). New York, NY McGraw-Hill Educ. Johnson, George B. (2017). Essentials to the living world. New York, NY McGraw- Hill Educ. https://ebookcentral.proquest.com Starr, Cecie (2015). Biology: A Human Emphasis (9th edition). Australia Cengage. Learning. https://ebookcentral.proquest.com Photosynthesis https://youtu.be/KfvYQgT2M-k Cellular Respiration https://youtu.be/pNzFYBA2Ofg Since you already know the basic concepts in the Photosynthesis and Cellular Respiration. Let us determine your understanding of the ideas presented in the unit content by answering the following: Activity 1 1. ___________ Which types of organisms are autotrophs? 2. ____________Which types of organisms are heterotrophs? 82 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 3. ____________What substance is the by-product of photosynthesis that is used for completing of cellular respiration? 4. ____________What is the ultimate original source of energy for all living things on Earth? 5. ____________What is ATP? 6. ____________ How many phosphates does ATP have? 7. ____________ What is the by-product of photosynthesis? 8. ____________ Why do the leaves of plants appear green to the human eye? 9. ____________ Why do plant root cells not have chloroplasts? 10. ____________ It is the name referred to the process that takes place when organic compounds are broken down in the absence of oxygen. Activity 1. In this activity you are expected to give a detailed explanation of your answer to the following questions. 1. What is the photosynthesis and cellular respiration equation? __________________________________________________________________________________ __________________________________________________________________________________ 2. What is the real benefit of fermentation? Give at least three important products of fermentation commonly used by the society. __________________________________________________________________________________ __________________________________________________________________________________ 3. What is the importance of photosynthesis and cellular respiration to us? __________________________________________________________________________________ __________________________________________________________________________________ 4. Explain how cellular respiration complements photosynthesis. __________________________________________________________________________________ __________________________________________________________________________________ 83 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 5. What is the ultimate end product of cellular respiration? __________________________________________________________________________________ __________________________________________________________________________________ Activity 1. Based on the discussion of the essential concepts in Photosynthesis and Cellular Respiration and the laboratory activities you have done, what do you think are the three most significant lessons you have learned. Write your answers below. 1. _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ 2. _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ 3. _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ Do you have any questions for clarification? Questions/Issues Answers 1. 2. 84 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 3. 4. 5. Photosynthesis Cellular Respiration Glycolysis Kreb’s Cycle Calvin Cycle Fermentation Electron Transport Chain Photosystem ATP Light Dependent Reaction Chloroplast Mitochondria Big Picture in Focus ULO-b. discuss the anatomy and physiology of Human Digestive System. In this segment, the important terminologies related to the anatomy and physiology of the Human Digestive System, which was denoted in the ULO-b, will be operationally and theoretically defined to establish a collective understanding needed for the discussion of the topics. You will encounter these vocabularies as we go through the details of the Human Digestive System's anatomy and physiology. Please refer to these definitions when you have difficulty in understanding some concepts. 1. Digestion Digestion is a catabolic process that turns the food we eat into absorbable nutrients that will be used for energy, growth, and cell development. The digestive system or the gastrointestinal tract is the primary organ system that functions for digestion. It is long winding tubes that begin from the mouth and ends at the anus. It is the breakdown of food, either chemically or mechanically, to utilize nutrients. 85 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 2. Absorption of Food The digested nutrients permeate in the epithelial membrane of the microvilli in the small intestine. This means that the digested food molecules pass through the small intestine wall and into our bloodstream. Once these molecules are in the blood, they are conducted to the different parts of the body where they are converted into energy and for the growth, development, and repair. 3. Gastric Juice These are colorless acidic digestive fluid secreted by the glands in the mucous membrane of the stomach lining. These contain 0.2 to 0.4 % hydrochloric acid (HCl) and several enzymes such as pepsin, which are very active in promoting digestion. 4. Pancreatic Juice These are substances produced from the pancreas that contains enzyme in response to the presence of partially digested food in the small intestine. These digestive juices include trypsinogen—Chrymotrypsinogen, lipase, amylase, and other enzymes responsible for the digestion of all nutrients. 5. Accessory Organs of the Digestive System These are organs in the body that are not directly involved in the digestive tract but played crucial roles in the digestion process. These include salivary glands, liver, gallbladder, pancreas, and appendix. In this portion, you will accomplish the Unit Learning Outcomes, which was stipulated in the Big Picture. This will be done for the sixth to seventh weeks of this course. Your understanding of the following concepts is essential to proceed with successive topics. You may refer to other available references to explore more on the subjects. Thus, you are expected to utilize other books, research articles, and other resources that are available in the university’s library, e.g., ebrary, search.proquest.com, etc. LECTURE PHYSIOLOGY AND ANATOMY OF HUMAN DIGESTIVE SYSTEM 86 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 Digestion is a catabolic process that turns the food we eat into absorbable nutrients that will be used for energy, growth, and cell development. The digestive system or the gastrointestinal tract is the primary organ system that functions for digestion. It is long winding tubes that begin from the mouth and ends at the anus. It breaks down food, either chemically or mechanically, to utilize the nutrients. Every organ of the digestive system function together to move the ingested food and liquids through the gastrointestinal tract until such time that the food is fully absorbed in the small intestine into the bloodstream. The large intestine will absorb the water, and the undigested food will become the stool. Nutrition – It is the process by which organisms obtain and utilize their food. There are three parts to Nutrition: Ingestion- the process of taking food into the digestive system so that it may be hydrolyzed or digested. Digestion- the breakdown of food (either chemically or mechanically) to utilize nutrients. Absorption - the passage of material through the lining of the intestine into the blood or through a cell membrane. Egestion /Elimination – getting rid of wastes. Types of Nutrients Micronutrients - Vitamins - Minerals, - Water Macronutrients - Proteins break into amino acids - Lipids break Fatty acids and glycerol - Carbohydrates break into glucose Phases of Digestion 1. Mechanical Phase –takes place in the mouth, converted into smaller pieces by the teeth, in chewing or mastication. 2. Chemical Phase – the food is acted upon by enzymes and other digestive juices to convert the large unit of food into smaller and simpler units. The Human Digestive System is composed of the gastrointestinal tract or digestive tract. These are tube organs that started from the mouth to the anus. The GI tract organs include the mouth, esophagus, stomach, small intestine, large intestine, rectum, and the anus. However, 87 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 these hollow organs are not enough to do the complete digestion, and they need to have complementary organs that secrete enzymes to digest the food material fully. These accessory organs involve the liver, pancreas, gallbladder, and salivary glands. Mouth Food begins its journey through the digestive system in the mouth, also known as the oral cavity. Inside the mouth are many accessory organs that aid in the digestion of food, the tongue, teeth, and salivary glands. Teeth chop food into small pieces moistened by saliva before the language, and other muscles push the food into the pharynx. The breaking down of food starts in the mouth when you ingest food, mechanical and chemical digestion. Food is chewed (masticated) mechanically. When masticating starts, the salivary glands secrete saliva, a digestive enzyme that contains amylase or the ptyalin. The proteins in the saliva break down the starches and help moistens the food. The bolus, a lump of moistening partially digested food, formed by the action of the mouth, teeth, and tongue, which moves more certainly through the esophagus into your stomach. The peristaltic movement of involuntary muscle contractions pushes the food along the esophagus. To avoid choking, Epiglottis, a flap of cartilage, closes the trachea (windpipe) when swallowing, and food travels down the esophagus. Teeth - are 32 small, hard organs found along the anterior and lateral edges of the mouth. Each tooth is made of a bone-like substance called dentin and covered in a layer of enamel, the hardest substance in the body. The teeth are designed for cutting and grinding food into smaller pieces. Tongue - is located on the inferior portion of the mouth, just posterior and medial to the teeth. It is a small organ made up of several pairs of muscles covered in a thin, bumpy, skin-like layer. Salivary Glands - are accessory organs that produce a watery secretion known as saliva. Saliva helps to moisten food and begins the digestion of carbohydrates. The body also uses saliva to lubricate food as it passes through the mouth, pharynx, and esophagus. Pharynx The pharynx, or throat, is a funnel-shaped tube connected to the posterior end of the mouth. The pharynx is responsible for the passing of masses of chewed food from the mouth to the esophagus. The pharynx also plays an essential role in the respiratory system. Air from the nasal cavity passes through the pharynx on its way to the larynx and eventually, the lungs. Because the pharynx serves two different functions, it contains a flap of tissue known as the epiglottis that acts as a switch to route food to the esophagus and air to the larynx. Esophagus The esophagus is a muscular tube connecting the pharynx to the stomach that is part of the upper gastrointestinal tract. It carries swallowed masses of chewed food along its length. At the esophagus's inferior end is a muscular ring called the lower esophageal sphincter or cardiac sphincter. This sphincter's function is to close off the end of the throat and trap food in the stomach. 88 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 Stomach The stomach is a muscular sac located on the left side of the abdominal cavity, just inferior to the diaphragm. This major organ acts as a storage tank for food so that the body has time to digest large meals properly. The stomach also contains hydrochloric acid and digestive enzymes that continue the digestion of food that began in the mouth. Glands in your stomach lining make stomach acid and enzymes that break down food. Muscles of your stomach mix the food with these digestive juices. These are colorless acidic digestive fluid secreted by the glands in the mucous membrane of the stomach lining. These contain 0.2 to 0.4 % hydrochloric acid (HCl) and several enzymes such as pepsin, which are very active in promoting digestion. Small Intestine The small intestine is a long, thin tube about 1 inch in diameter and about 10 feet long that is part of the lower gastrointestinal tract. It is located just inferior to the stomach and takes up most of the abdominal cavity space. The entire small intestine is coiled like a hose, and the inside surface is full of many ridges and folds. These folds are used to maximize the digestion of food and absorption of nutrients. By the time food leaves the small intestine, around 90% of all nutrients have been extracted from the food that entered it. Liver and Gallbladder The liver is a roughly triangular accessory organ of the digestive system located to the right of the stomach, just inferior to the diaphragm and superior to the small intestine. The liver weighs about 3 pounds and is the second-largest organ in the body. The liver has many different functions in the body, but the primary purpose in digestion is the production of bile and its secretion into the small intestine. Bile is a bitter, greenish-yellow alkaline fluid, stored in the gallbladder between meals and upon eating is discharged into the duodenum where it aids the process of digestion. The gallbladder is a small, pear-shaped organ located just posterior to the liver. The gallbladder is used to store and recycle excess bile from the small intestine to be reused for the digestion of subsequent meals. Pancreas The pancreas is a large gland located just inferior and posterior to the stomach. It is about 6 inches long and shaped like a short, lumpy snake with its “head” connected to the duodenum and its “tail” pointing to the left wall of the abdominal cavity. The pancreas secretes digestive enzymes into the small intestine to complete the chemical digestion of foods. Large Intestine The large intestine is a long, thick tube about 2 ½ inches in diameter and about 5 feet long. It is located just inferior to the stomach and wraps around the small intestine's superior and lateral border. The large intestine absorbs water and contains many symbiotic bacteria that aid in the breaking down wastes to extract some small amounts of nutrients. Feces in the large intestine exit the body through the anal canal. 89 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 Digestive Homeostasis Disorders 1. Ulcers – an erosion of the surface of the alimentary canal generally associated with some kind of irritant. 2. Constipation – a condition in which the large intestine is emptied with difficulty. Too much water is reabsorbed, and the solid waste hardens. 3. Diarrhea – a gastrointestinal disturbance characterized by decreased water absorption and increased peristaltic activity of the large intestine. This results in increased, multiple, watery feces. This condition may result in severe dehydration, especially in infants. 4. Appendicitis – an inflammation of the appendix due to infection. Standard treatment is the removal of the appendix via surgery. 5. Gallstones – an accumulation of hardened cholesterol and calcium deposits in the gallbladder. It can either be “passed” or surgically removed. 6. Anorexia Nervosa - a psychological condition where an individual thinks they appear overweight and refuses to eat. Weighs 85% or less than what is developmentally expected for age and height. Young girls do not begin to menstruate at the appropriate age. 7. Heart Burn – acid from the stomach backs up into the esophagus. Performance Task/ Laboratory Activities (Instructions and procedures will be provided by the subject teacher.) Laboratory Activity # 11 You can also refer to the sources below to help you further understand the lesson: Mason, Kenneth A. (2017). Biology (11th edition). New York, NY McGraw-Hill Educ. Johnson, George B. (2017). Essentials to the living world. New York, NY McGraw- Hill Educ. https://ebookcentral.proquest.com Starr, Cecie (2015). Biology: A Human Emphasis (9th edition). Australia Cengage. Learning. https://ebookcentral.proquest.com Human Digestive System https://youtu.be/X3TAROotFfM 90 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 Since you already know the basic concepts in the study of the Human Digestive System. Let us determine your understanding of the ideas presented in the unit content by answering the following: Activity 1 – Identification 1. ___________It is a group of organs working together to convert food into energy and basic nutrients to feed the entire body. 2. ___________ It is also known as the oral cavity. 3. ___________ It is a phase of digestion that takes place in the mouth, converted into smaller pieces by the teeth, in the process of chewing or mastication. 4. ___________ It is a long, thin tube about 1 inch in diameter and about 10 feet long that is part of the lower gastrointestinal tract. It is located just inferior to the stomach and takes up most of the space in the abdominal cavity. 5. ___________ It is the phase of Digestion wherein the food is acted upon by enzymes and other digestive juices to convert the large unit of food into smaller and simpler units. 6. ___________ They are accessory organs that produce a watery secretion known as ptyalin. 7. ___________ These are substances that complete the digestion process. 8. ____________ It is responsible for the storage and recycle excess bile from the small intestine so that it can be reused. 9. ____________ responsible for the lipid digestion. 10. _____________ site where the complete digestion of the lipids occurs. 91 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 Activity 1. In this activity you are expected to give a detailed explanation of your answer to the following questions. 1. How does aging affect digestion? _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ 2. What digestion of food groups is mostly affected by cholecystectomy or surgical removal of the gallbladder? Why? _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ 3. Could a person survive without the stomach? Why or Why not? _____________________________________________________________________ _____________________________________________________________________ 4. What are the benefits and risks of having bacteria in our gastrointestinal tract? _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ Activity 1. Based on the discussion of the essential concepts in the Human Digestive System and the laboratory activities you have done, what do you think are the three most significant lessons you have learned. Write your answers below. 1. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 2. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 92 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 3. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ _________________________________________________________________ Do you have any questions for clarification? Questions/Issues Answers 1. 2. 3. 4. 5. Gastrointestinal Tract Digestive System Amylase Gastric Juices Accessory Organs Pepsin Pancreatic Juice Peristalsis Lipase Intestinal Juices Bolus Salivary glands 93 | P a g e College of Arts and Sciences Education General Education - Science 2nd Floor, DPT Building, Matina Campus, Davao City Phone No.: (082)300-5456/305-0647 Local 134 94 | P a g e
