BIOCHEM_MODULE Biochemistry for Nursing PDF

SCHOOL OF NURSING NBICHM1 MICROBIOLOGY FOR NURSES NBICHL1 LEC AND LAB Prepared by: Vivien Rios, MAN, RN, RM A Self-regulated Learning Module Elton John Delos Santos MAN,MaEd,RN Genesis N. Del...

SCHOOL OF NURSING NBICHM1 MICROBIOLOGY FOR NURSES NBICHL1 LEC AND LAB Prepared by: Vivien Rios, MAN, RN, RM A Self-regulated Learning Module Elton John Delos Santos MAN,MaEd,RN Genesis N. Dela Cruz, MAN, RN Richard S. Rosalin,RN A Self-regulated Learning Module 1 Bryan C. Robles, MSN, RN  TABLE OF CONTENTS INTRODUCTION OF THE MODULE Course Code and Title 4 Course Description 4 Requirements of the Course 4 Learning Outcomes 5 Study Schedule 5 Letter of Undertaking 7 UNIT I. INTRODUCTION A. Foundations 8 B. Water and pH 14 C. Laboratory 27 Check for Facts and Understanding 34 UNIT II. BIOCHEMISTRY OF THE CELL A. Review on Parts of the Cell 49 B. DNA & RNA 54 C. Laboratory 63 Check for Facts and Understanding 56 UNIT III. BIOCHEMISTRY OF DIGESTION A. Definition 67 B. Mechanism of Digestion 67 C. Phases of Digestion 71 D. Laboratory 79 Check for Facts and Understanding 89 UNIT IV. CARBOHYDRATES A. Definition 89 B. General Structure 90 C. Importance and General Functions 91 D. Classifications 92 E. Digestion, Absorption, and Metabolism 113 F. Metabolic Pathway 119 G. The Main Powerhouse 132 H. Clinical Significance of CHO 143 I. Laboratory 150 Check for Facts and Understanding 165 UNIT V. PROTEINS A. Definitions 173 B. Amino Acid 190 C. Enzymes 199 D. Laboratory 211 Check for Facts and Understanding 218 A Self-regulated Learning Module 2 UNIT VI. LIPIDS A. Definition and Function 219 B. Classifications 219 C. Properties 220 D. Digestion and Absorption 223 E. Lipid Metabolism 225 F. Lipolysis 226 G. Knoop’s Beta 227 H. Synthesis and Oxidation 238 I. Lipid Storage Room 238 J. Test for lipids 238 K. Clinical significance for lipid metabolism 241 Check for Facts and Understanding 252 EVALUATION OF THE COURSE COURSE SYLLABUS REFERENCES A Self-regulated Learning Module 3  INTRODUCTION OF THE MODULE Course Code: NBICHM1, NBICHL1 Course Title: Biochemistry for Nursing Course Description: This course deals with the study of the chemical composition of living matter. It deals with the study of the structure and function of carbohydrates, lipids, proteins and amino acids. It also includes the different biochemical mechanisms involved in the breakdown of complex bio- molecules which lead to the synthesis of important metabolites and the production of energy. Emphasis is also given on the medical, clinical, and human implications from the concepts presented, so designed to enable students to understand it and also to help students appreciate their importance in the chemical processes of the human body, to enable them to use this knowledge in their chosen fields of specialization. Requirements of the Course: 1. Recitation. The learners are expected to actively participate during online interactive lectures. They will be asked by the clinical instructor during the interactive lecture and they are expected to share their thoughts and ideas relevant to the subject matter. 2. Quiz. Online quizzes will be administered by the instructor every after each chapter with the use of Google forms. The learners will be given enough time to complete and turn in the quiz before the deadline. Offline quizzes will be provided to all learners who have no connectivity and should submit them on the set deadline by the clinical instructor. 3. Laboratory Experiments/Activities. The learners are expected to complete and turn in laboratory activities per chapter through Google Forms. All other laboratory activities that require the use of laboratory room and equipment should be done in the school as soon as the situation and authorities permit. Refer to the laboratory activities of each chapter for further instructions. 4. Examination. Online examination or unit quizzes should be administered through Google Forms, but it could be done in the school as soon as face-to-face will be allowed. 5. Vlog. The learners are required to record a vlog presenting “Nutrients absorption of the Body” with the use of visual aids that are made of any recyclable materials or any available materials at home. The vlog should be at minimum of 3 minutes and maximum of 5 minutes in duration. The learners are given freewill to express their creativity on recording a vlog about the said topic. 6. Attendance. The learner expected to attend an online interactive lecture through google meet or zoom as part of the requirements. Learners who experience weak or no internet connection must notify his/her instructor immediately. A Self-regulated Learning Module 4 Learning Competencies: After the course on Biochemistry for Nursing, the learners are expected to: 1. apply knowledge of physical, social, natural and health sciences and humanities in the practice of nursing by integrating relevant principles of social, physical, natural and health sciences and humanities in a given health and nursing situation; 2. provide safe, appropriate, and holistic care to individuals, families, population groups, and community utilizing nursing process by instituting appropriate corrective actions to prevent or minimize harm arising from adverse effects; 3. apply guidelines and principles of evidence-based practice in the delivery of care by providing appropriate evidence-based nursing care using a participatory approach based on: variety of theories and standards relevant to health and healing, research, clinical practice, client preferences, client and staff safety, customer care standards, and 4. practice beginning management and leadership skills in using systems approach in their delivery of client care by managing resources (human physical, financial, time) efficiency and effectively. Study Schedule Grading Period Topics Schedule First Grading UNIT I. INTRODUCTION Week 1 to 2 A. Foundations B. Water and pH C. Laboratory Check for Facts and Understanding UNIT II. BIOCHEMISTRY OF THE CELL Week 3 to 4 A. Review on Parts of the Cell B. DNA & RNA C. Laboratory Check for Facts and Understanding Week 5 to 6 UNIT III. BIOCHEMISTRY OF DIGESTION A. Definition B. Mechanism of Digestion C. Phases of Digestion D. Laboratory Check for Facts and Understanding A Self-regulated Learning Module 5 Midterms UNIT IV. CARBOHYDRATES Week 6 to 7 A. Definition B. General Structure C. Importance and General Functions D. Classifications E. Digestion, Absorption, and Metabolism F. Hexose Monophosphate G. The Main Powerhouse Week 8 to 9 H. Clinical Significance of CHO I. Laboratory Check for Facts and Understanding UNIT V. PROTEINS Week 10 to 11 A. Definitions B. Enzymes C. Laboratory Week 12 Finals D. Amino Acids Week 13 to 15 E. Laboratory Check for Facts and Understanding Week 16 to 18 UNIT VI. LIPIDS A. Definition and Function B. Classifications C. Properties D. Digestion and Absorption E. Lipid Metabolism F. Lipolysis G. Knoop’s Beta H. Synthesis and Oxidation I. Lipid Storage Room J. Test for Lipids K. Clinical Significance L. Laboratory Check for Facts and Understanding Clinical Instructors Genesis Dela Cruz, MAN, RN [email protected] Vivien Rios, MAN, RN, RM [email protected] Bryan C. Robles, MSN, RN [email protected] Richard S. Rosalin, RN [email protected] Elton John Delos Santos, MAN, MaEd, RN [email protected] A Self-regulated Learning Module 6 Letter of Undertaking To Whom It May Concern, As a student of the School of Nursing enrolled in the course, Biochemistry for Nursing, assure that I will utilize this module as learning material and will actively participate in each and every learning activities such as but not limited to online learning, blended learning, and self-directed learning. Furthermore, I solemnly swear that I will not commit plagiarism by citing all references I will use in every requirement that I will submit, and will not cheat by practicing honesty and integrity with the best of my abilities in all learning assessments that my professor will administer. Sincerely, ___________________________________ _________________ (Signature of the Student) Date A Self-regulated Learning Module 7  UNIT I. INTRODUCTION Objectives After Studying this unit, you should be able to: a. memorize the terms commonly used in Biochemistry and other concepts necessary to understand the course; b. highlight the aims and significant events in the history of Biochemistry; c. identify the importance of Biochemistry to different disciplines; d. describe the properties of water and those of inorganic acids, bases, and salts; e. distinguish among solutions, colloids, and suspensions, and f. explain the role of buffer systems in homeostasis. A. FOUNDATIONS 1. Definition of Terms 1) Matter—is any substance that has mass and takes up space by having volume. It exists in three (3) states: solid, liquid, and gas. 1. Solids—are compact and have a definite shape and volume. Example, bones and teeth. 2. Liquids—have a definite volume and assume the shape of their container. Examples: blood plasma. 3. Gasses—have neither a definite shape nor volume. Example: oxygen and carbon dioxide. b. Chemical Elements—building blocks of all forms of living and nonliving matter. c. Chemical Symbol—one or two letters of the element’s name in English, Latin, or another language. Example, H for hydrogen, C for carbon, O for oxygen, Ca for calcium, and Na for sodium (natrium = sodium). d. Atoms—the smallest units of matter that retain the properties and characteristics of the element. e. Subatomic Particles—are the basic composition of an atom. Three (3) types of subatomic particles: protons, neutrons, and electrons. 1. Protons—positively charged (p ) + 2. Neutrons—uncharged or neutral (n ) 0 3. Electrons—negatively charged (e ) - f. Ion—is an atom that has a positive or negative charge because it has equal numbers of protons and electrons. Ionization—is the process of giving up or gaining electrons. g. Molecule—is the resulting combination of two or more atoms that share electrons. Molecular formula—indicates the elements and the number of atoms of each element that make up a molecule. h. Compound—is a substance that contains atoms of two or more different elements. Example, water (H O), sodium chloride/table salt (NaCl). 2 i. Free Radical—is an atom or group of atoms with an unpaired electron on the outermost shell. Example, superoxide. j. Chemical Bonds—are the forces that hold together the atoms of a molecule or a compound. k. Ionic Bond—is the force of attraction that holds together ions with opposite charges. A Self-regulated Learning Module 8 l. Cation—positively charged ion. Example, hydrogen ion, Sodium ion, Potassium ion, Ammonium ion, Magnesium ion, Calcium ion, Iron (II) ion, Iron (III) ion. m. Anion—negatively charged ions. Example: Fluoride ion, Chloride ion, Iodide ion, Hydroxide ion, Bicarbonate ion, Oxide ion, Sulfate ion, Phosphate ion. n. Electrolyte—an ionic compound that breaks apart into positive and negative ions in solution. Most ions in the body are dissolved in body fluids as electrolytes, so named because their solutions can conduct an electric current. o. Covalent Bond—two or more atoms share electrons rather than gaining or losing them. p. Hydrogen Bond—forms when a hydrogen atom with a partial positive charge attracts the partial negative charge of neighboring electronegative atoms, most often larger oxygen or nitrogen atoms. q. Chemical Reaction—occurs when new bonds form or old bonds break between atoms. r. Metabolism—refers to all the chemical reactions occurring in the body. s. Energy—is the capacity to do work. Two principal forms: potential energy and kinetic energy. 1. Potential Energy—energy stored by matter due to its position. 2. Kinetic Energy—the energy associated with matter in motion. t. Chemical Energy—is a form of potential energy that is stored in the bonds of compounds and molecules. 6 u. Activation Energy—is the collision energy needed to break the chemical bonds of the reactant molecules so a reaction can start. v. Catalyst—are chemical compounds that speed up chemical reactions by lowering the activation energy needed for a reaction to occur. The most important catalysts in the body are enzymes. w. Synthesis Reaction—the process of combination of two or more atoms, ions, or molecules to form new and larger molecules. The word synthesis means “to put together”. x. Anabolism—collectively refers to all of the synthesis reactions that occur in your body. y. Decomposition Reaction—splits up large molecules into smaller atoms, ions, or molecules. z. Catabolism—collectively refers to the decomposition reactions that occur in your body. aa. Exchange Reaction—consists of both synthesis and decomposition reactions. bb. Reversible Reaction—the products can revert to the original reactants. cc. Oxidation—refers to the loss of electrons; in the process the oxidized substance releases energy. dd.. Reduction—refers to the gain of electrons; in the process the reduced substance gains energy. ee. Oxidation-Reduction Reaction—is always parallel; when a substance is oxidized, another is reduced at the same time. 2. Aims and History  6 Mid 1700: Karl Schelle, Swedish founder of biochemistry, studied chemical composition of matter.  1780s Antoine Lavoisier proposed that the combustion of a candle is similar to the & respiration of animals, as both need O. 2  For the first time a physiological process was explained with reference to a nonliving mechanism.  Until - the early 1800’s “vitalism” was a common belief: the compounds found in living organisms (i.e., organic molecules) can only be produced by living organisms and could not be produced in the laboratory. A Self-regulated Learning Module 9   Now an obsolete scientific doctrine, vitalists argued that it was the presence of “vital force” (life force or spirit) that distinguished the living organic world from the inanimate inorganic world. - Friedrich Wöhler disproved this belief (i.e., vitalism) in 1828 by synthesizing urea, an organic molecule and a waste product of animal metabolism, from ammonium cyanate, an inorganic molecule obtained from mineral (i.e., nonliving) sources.  Many science historians consider this in vitro synthesis of urea by Wöhler as the starting point of Biochemistry. -  However, many consider Eduard Buchner’s first demonstration of alcoholic fermentation in 1893 in cell-free yeast extracts as the starting point for the birth of biochemistry.  This was another blow to the vitalistic thinking, showing that the presence of living yeast cells was not needed for fermentation. Previously, scientists believed that only living cells could catalyze such complex biological reactions. - Miller-Urey Experiment  Experiments recreating the atmosphere of primitive earth, with the energy sources and temperatures have led to the spontaneous formation of amino acids and other biologically significant molecules.  The Miller-Urey experiment showed that a variety of organic molecules, including the j amino acids could form in an early, reducing atmosphere.  Thus, living things obey the standard laws of physics and chemistry.  And, no “vitalistic” force is required to explain life at the molecular level.  = 1810s-1830s: A major substance from animals and plants was identified, composed of C, H, O, and N. The term “Protein”, meaning the most important thing, was first used in 1838.  1840: Schleiden and Schwann formulated the Cell Theory.  1875: - Walter Flemming discovered chromosomes.  1850s-1890s: Carbohydrates, lipids, and nucleic acids were recognized. -  The term “biochemistry” was coined in the 1870s by a German scientist, Carl Newberg.  1925: Embden and Mayerhoff described the glycolytic pathway.  1937: Hans Kreb proposed Kreb cycle.  1953: James Watson and Francis Crick described the double helical structure of DNA.  1997: Paul Boyer and Jay Walker discovered the “Rotary Engine” that generated ATP.  Danish J. Skou studied the “pump” that drives sodium and potassium across membranes.  Stanley Frusiner discovered the organism that causes “Mad Cow Disease”.  Ruska et. al discovered the electron microscope and provided a whole new level of insight into cellular structure. 25 Biochemistry The study of the molecular basis of life or understanding life phenomena in chemical terms.  The focus and aim of biochemistry are to understand how biological molecules give rise to the processes that occur within living cells and whole organisms.  3. Importance of Biochemistry to Different Disciplines A Self-regulated Learning Module 10  It is used in clinical diagnosis, manufacturing of various biological products, treatment of diseases, in nutrition, agriculture etc. The study of biochemistry helps one understand the actual chemical concepts of biology. That is the functioning of various body processes and physiology by uses of biomolecules. a. Dentistry  The aims, attitude and techniques of biochemistry are as relevant to dentistry as to medicine or to any aspect of biology 1. To understand the true nature of dental disease. All diseases have a biochemical basis. 2. To give dental patients the necessary or appropriate dietary advice to prevent dental diseases. 3. Special relevance to dentistry is areas of blood coagulation and effects of drugs and other injected substances on tissue and cells 4. Understanding the physicochemical process of resorption and deposition of bone materials and its matrix is essential to orthodontics.  As for the future, methods to prevent or cure tooth decay are likely to involve a biochemical approach, like the caries vaccine. 1. The role of fluoride is now well established and its role to re-mineralize a carious lesion or chemically modify a tooth, the enamel surface and its bacterial population offer scope for further investigation. 6 b. Agriculture  biochemistry plays a valuable role in farming, fishery, poultry, sericulture, beekeeping etc;  Prevent diseases: It helps for prevention, treatment of diseases and also increases the production or yield.  Enhance growth: Biochemistry gives an idea of how the use of fertilizers can increase plant growth, their yield, quality of food etc.  Enhance Yield: Some hormones promote growth, while other promote flowering fruit formation etc. In fisheries, use of substances to promote fish growth, their reproduction, etc. can be understood.  Adulteration: Even the composition of food material produced, their alteration or adulteration for example in honey can be found by biochemical tests. Biochemistry tests help prevent contamination.  Biochemical tests for the pesticide residues or other toxic waste in plant, food grain and soil can be evaluated. Hence during import and export of food grains a biochemical check of the toxic residues is done to fix the quality.  In animal husbandry, the quality of milk can be checked by biochemical tests. It also helps diagnose any disease condition in animals and birds.  Biochemical tests for the pesticide residues or other toxic waste in plant, food grain and soil can be evaluated. Hence during import and export of food grains a biochemical check of the toxic residues is done to fix the quality.  In fisheries, the water quality is regularly monitored by biochemical tests. Any drastic change in water chemistry & composition of fishery ponds can lead to the vast death of fishes and prawns, hence the tests are done on regular basis to see salt content (calcium content), pH, accumulation of waste due to not changing water for long etc. A Self-regulated Learning Module 11 c. Plants  Photosynthesis: This describes how carbohydrates are synthesized by use of sunlight, CO , and water in the green leaves of plants. It goes on to explain about 2 different complex enzymes involved in the process to combine the energy of the sun within the molecules of H O+ CO in the form of carbohydrates. 2 2  Respiration: By use of the above photosynthesis pathway, plants leave out Oxygen while taking up Carbon dioxide from the air.  Different sugars: Biochemistry defines different types of carbohydrates formed in plants like trioses (3 carbon sugars i.e. glyceraldehyde), tetroses (4), pentoses (5), hexoses (6= glucose), heptuloses (7) etc. Heptuloses are the carbohydrates which go on to form the nucleic acids i.e. deoxyribonucleic acid (DNA), ribonucleic acid (RNA)  Plants secondary metabolites: Biochemistry also describes how the plant products like gums, tannins, alkaloids, resins, enzymes, phytohormones are formed inside the plants  Other functions: It also describes how plant fruits get ripened, how plant seed germinates, the respiration process inside the plant cell, how proteins and amino acids are formed on rough endoplasmic reticulum and fats are formed on smooth ER. d. Nutrition  In nutrition, biochemistry describes food chemistry. For maintenance of health, optimum intake of many biochemicals like macro, micronutrients, vitamins, minerals, essential fatty acids & water is necessary.  Food chemistry gives an idea of what we eat, i.e. it’ s components like carbohydrates, proteins, fats, etc. and also the possible physiological alteration due to their deficiency.  The role of nutrients: Due to biochemistry the importance of vitamins, minerals, essential fatty acids, their contribution to health were known. Hence there is a frequent recommendation for inclusion of essential amino-acids, cod liver oil, salmon fish oil etc. by physicians and other health and fitness experts. The nutrients value of food material can also be determined by biochemical tests.  The physician can prescribe to limit usage of certain foods like excess sugar for diabetics, excess oil for heart & lung problem prone patients etc. As these carbohydrate and fat diets can inhibit the recovery rate from said disorder. This knowledge is due to their idea of food chemistry and relate e. Pharmacology  Drug Constitution: Biochemistry gives an idea of the constitution of the drug, its chances of degradation with varying temperature etc. How modification in the medical chemistry helps improve efficiency, minimize side effects etc.  Drug storage: The storage condition required can be estimated by the biochemical test. For example, many enzymes, hormones are stored for dispensing. These get deteriorated over time due to temperature or oxidation, contamination and also due to improper storage.  Drug metabolism: It also gives an idea of how drug molecules are metabolized by many biochemical reactions in presence of enzymes. A Self-regulated Learning Module 12  This helps to avoid drugs which have a poor metabolism or those with excessive side effects from being prescribed or dispensed to the patient. f. Medicine  Biochemistry is a valuable subject in medicine without which there would have been no such advancement in the field.  Physiology: Biochemistry helps one understand the biochemical changes and related physiological alteration in the body. Pathology of any disease is studied through biochemical changes.  Pathology: Based on the symptoms described by the patient, the physician can get a clue on the biochemical change and the associated disorder. For example, if a patient complains about stiffness in small joints, then the physician may predict it to be gout and get confirmed by evaluating uric acid levels in the blood. As uric acid accumulation in blood results in gout.  Nutrition deficiency: In the present scenario, many people rely on taking multivitamin & minerals for better health. The function and role of the vitamin in the body are described only by biochemistry.  Hormonal deficiency: There are many disorders due to hormonal imbalance in especially women and children. The formation, role of hormones in the normal body function is taught in biochemistry by which the physician can understand the concerned problem during treatment. g. Nursing  In nursing, the importance of clinical biochemistry is INVALUABLE. When a patient is in the hospital nurses need to keep a watch on how his condition is progressing through clinical biochemistry. That is the treatment helping him recover from said condition etc. Almost all the diseases or disorders have some biochemical involvement. So, the diagnosis of any clinical condition is easily possible by biochemical estimations:  Kidney function test: For example, in kidney disorders, other chemotherapy treatments etc. urine tests help understand the extent of excretion of drugs or other metabolites, the change in pH, the color of urine etc.  Serum cholesterol test: Evaluation of blood cholesterol level and other lipoproteins helps understand the proneness of the patient to cardiovascular diseases.  Blood test: In diabetes, biochemical analytical test for blood glucose level (above 150mg/ deciliter helps one understand the severity of diabetes disorder. Another biochemical test for ketones bodies in urine also indicates the stage of diabetes. The appearance of ketone bodies or ketone urea is mostly the last stage of diabetes.  Liver function tests help understand the type of disease or damage to the liver, the effect of any medication on liver etc.  Thus, the importance of clinical biochemistry is to help the nurse monitor the patient’s condition regularly during the treatment. Learn more Online! Introduction to Biochemistry: https://www.youtube.com/watch?v=CHJsaq2lNjU History of Biochemistry: https://www.youtube.com/watch?v=RpDx0DVJmeo A Self-regulated Learning Module 13 B. WATER AND pH 8 1. Water  It is the most important and abundant inorganic compound in all living systems.  Nearly all the body’s chemical reactions occur in a watery medium. Water has many properties that make it such an indispensable compound for life.  The important property of water is its E polarity—the uneven sharing of valence electrons that confers a partial negative charge near the one oxygen atom and two partial positive charges near the two hydrogen atoms in a water molecule. Diagram of Atomic and Molecular Structure Structural Molecular Formula Formula (Source: Tortora, G. J. & Derrickson, B. (2014). Principles of Anatomy & Physiology. 14th ed. New Jersey, USA: John Wiley & Sons, Inc.) a. Water as a Solvent 6 Solution—composed of solvent and solute. = Solvent—dissolves the solute. Solute—being dissolved by the solvent. Example, your sweat is a dilute solution of water (the solvent) plus small amounts of salts (the solutes).  The versatility of water as a solvent for ionized or polar substances is due to its polar covalent bonds and its bent shape, which allows each water molecule to interact with several neighboring ions or molecules. Solutes that are charged or contain polar covalent bonds are6 hydrophilic (hydro- = water; -philic = loving), which means they dissolve easily in water. Common examples of hydrophilic solutes are sugar and salt. Molecules that contain mainly nonpolar covalent bonds, by contrast, are - hydrophobic (-phobic = fearing). They are not very water-soluble. Examples of hydrophobic compounds include animal fats and vegetable oils.  To understand the dissolving power of water, consider what happens when a crystal of a salt such as sodium chloride (NaCl) is placed in water. The electronegative oxygen atom in water molecules attracts the sodium ions (Na ), + and the electropositive hydrogen atoms in water molecules attract the chloride A Self-regulated Learning Module 14  ions (Cl ). Soon, water molecules surround and separate Na and Cl ions from - + - each other at the surface of the crystal, breaking the ionic bonds that held NaCl together. The water molecules surrounding the ions also lessen the chance that Na and Cl will come together and re-form an ionic bond. + -  The ability of water to form solutions is essential to health and survival. Because water can dissolve so many different substances, it is an ideal medium for metabolic reactions. Water enables dissolved reactants to collide and form products. Water also dissolves waste products, which allows them to be flushed out of the body in the urine. (Source: Tortora, G. J. & Derrickson, B. (2014). Principles of Anatomy & Physiology. 14th ed. New Jersey, USA: John Wiley & Sons, Inc.) - b. Water in Chemical Reactions  Water serves as the medium for most chemical reactions in the body and participates as a reactant or product in certain reactions. During digestion, for - example, decomposition reactions break down large nutrient molecules into smaller molecules by the addition of water molecules. This type of reaction is called hydrolysis (hıˉ-DROL-i-sis; -lysis = to loosen or break apart). Hydrolysis reactions enable dietary nutrients to be absorbed into the body. By contrast, A Self-regulated Learning Module 15  when two smaller molecules join to form a larger molecule in a dehydration synthesis reaction (de- = from, down, or out; hydra- = water), a water molecule is one of the products formed. (Source: Tortora, G. J. & Derrickson, B. (2014). Principles of Anatomy & Physiology. 14th ed. New Jersey, USA: John Wiley & Sons, Inc.) - c. Thermal Properties of Water  In comparison to most substances, water can absorb or release a relatively large amount of heat with only a modest change in its own temperature. For this reason, water is said to have a high heat capacity. The reason for this property - is the large number of hydrogen bonds in water. As water absorbs heat energy, some of the energy is used to break hydrogen bonds. Less energy is then left over to increase the motion of water molecules, which would increase the water’s temperature. The high heat capacity of water is the reason it is used in automobile radiators; it cools the engine by absorbing heat without its own temperature rising to an unacceptably high level. The large amount of body water has a similar effect: It lessens the impact of environmental temperature changes, helping to maintain body temperature homeostasis.  Water also requires a large amount of heat to change from a liquid to a gas. Its - heat of vaporization is high. As water evaporates from the surface of the skin, it removes a large quantity of heat, providing an important cooling mechanism. = d. Water as Lubricant  Water is a major component of mucus and other lubricating fluids throughout the body. Lubrication is especially necessary in the chest (pleural and pericardial cavities) and abdomen (peritoneal cavity), where internal organs touch and slide over one another. It is also needed at joints, where bones, ligaments, and tendons rub against one another. Inside the gastrointestinal tract, mucus and other watery secretions moisten foods, which aids their smooth passage through the digestive system. 2. Inorganic Acids, Bases, and Salts When inorganic acids, bases, or salts dissolve in water, they dissociate; that is, they separate into ions and become surrounded by water molecules. An acid is a substance that dissociates into one or more hydrogen ions (H ) and one or more anions. + Because H is a single proton with one positive charge, an acid is also referred to as a + proton donor. A base, by contrast, removes H+ from a solution and is therefore a proton - A Self-regulated Learning Module 16  acceptor. Many bases dissociate into one or more hydroxide ions (OH ) and one or more - cations. & A salt, when dissolved in water, dissociates into cations and anions, neither of which is H or OH. In the body, salts such as potassium chloride are electrolytes that are + - important for carrying electrical currents (ions flowing from one place to another), especially in nerve and muscular tissues. The ions of salts also provide many essential chemical elements in intracellular and extracellular fluids such as blood, lymph, and the interstitial fluid of tissues. Acids and bases react with one another to form salts. For example, the reaction of hydrochloric acid (HCl) and potassium hydroxide (KOH), a base, produces the salt potassium chloride (KCl) and water (H2O). This exchange reaction can be written as follows: a. E Acid–Base Balance: The Concept of pH - To ensure homeostasis, intracellular and extracellular fluids must contain almost balanced quantities of acids and bases. The more hydrogen ions (H ) dissolved in a + solution, the more acidic the solution; the more hydroxide ions (OH ), the more basic - (alkaline) the solution. The chemical reactions that take place in the body are very sensitive to even small changes in the acidity or alkalinity of the body fluids in which they occur. Any departure from the narrow limits of normal H and OH concentrations greatly + - disrupts body functions. A solution’s acidity or alkalinity is expressed on the pH scale, which extends from 0 to 14. This scale is based on the concentration of H in moles per liter. A pH of 7 + means that a solution contains one ten-millionth (0.0000001) of a mole of hydrogen ions per liter. The number 0.0000001 is written as 1 _ 10_7 in scientific notation, which indicates that the number is 1 with the decimal point moved seven places to the left. To convert this value to pH, the negative exponent (–7) is changed to a positive number (7). A solution with a H concentration of 0.0001 (10_4) mol/L has a pH of 4; a solution with a + H concentration of 0.000000001 (10_9) mol/L has a pH of 9; and so on. It is important to + realize that a change of one whole number on the pH scale represents a tenfold change in the number of H. A pH of 6 denotes 10 times more H than a pH of 7, and a pH of 8 + + indicates 10 times fewer H than a pH of 7 and 100 times fewer H than a pH of 6. + + The midpoint of the pH scale is 7, where the concentrations of H and OH are + - equal. A substance with a pH of 7, such as pure water, is neutral. A solution that has more H than OH is an acidic solution and has a pH below 7. A solution that has more + - OH than H is a basic (alkaline) solution and has a pH above 7. - + A Self-regulated Learning Module 17 (Source: Tortora, G. J. & Derrickson, B. (2014). Principles of Anatomy & Physiology. 14th ed. New Jersey, USA: John Wiley & Sons, Inc.) # 3. Maintaining pH: Buffer Systems Although the pH of body fluids may differ, as we have discussed, the normal limits for each fluid are quite narrow. The table below shows the pH values for certain body fluids along with those of some common substances outside the body. Homeostatic mechanisms maintain the pH of blood between 7.35 and 7.45, which is slightly more basic than pure water. You will learn later on that if the pH of blood falls below 7.35, a condition called acidosis occurs, and if the pH rises above 7.45, it results in a condition called alkalosis; both conditions can seriously compromise homeostasis. Saliva is slightly acidic, and semen is slightly basic. Because the kidneys help remove excess acid from the body, urine can be quite acidic. Even though strong acids and bases are continually taken into and formed by the body, the pH of fluids inside and outside cells remains almost constant. One important reason is the presence of buffer systems, which function to convert strong acids or bases into weak acids or bases. Strong acids (or bases) ionize easily and contribute many H (or OH ) to a solution. Therefore, they can change pH drastically, which can + - disrupt the body’s metabolism. Weak acids (or bases) do not ionize as much and contribute fewer H (or OH ). Hence, they have less effect on the pH. The chemical + - compounds that can convert strong acids or bases into weak ones are called buffers. They do so by removing or adding protons (H ). + One important buffer system in the body is the carbonic acid– bicarbonate buffer system. Carbonic acid (H2CO3) can act as a weak acid, and the bicarbonate ion (HCO3 - ) can act as a weak base. Hence, this buffer system can compensate for either an excess or a shortage of H. For example, if there is an excess of H (an acidic condition), + + HCO3 can function as a weak base and remove the excess H , as follows: - + A Self-regulated Learning Module 18  If there is a shortage of H (an alkaline condition), by contrast, H2CO3 can function + as a weak acid and provide needed H as follows: + 4. Fluid and Electrolytes -- a. Fluid Compartments and Fluid Homeostasis In lean adults, body fluids constitute between 55% and 60% of total body mass in females and males, respectively. Body fluids are present in two main “compartments”—inside cells (intracellular) and outside cells (extracellular). About two-thirds of body fluid is intracellular fluid (ICF) (intra- = within) or cytosol, the fluid within cells. The other third, called extracellular fluid (ECF) (extra- = outside), is outside cells and includes all other body fluids. About 80% of the ECF is interstitial fluid (inter- = between), which occupies the microscopic spaces between tissue cells, and 20% of the ECF is plasma, the liquid portion of the blood. Other extracellular fluids that are grouped with interstitial fluid include lymph in lymphatic vessels; cerebrospinal fluid in the nervous system; synovial fluid in joints; aqueous humor and vitreous body in the eyes; endolymph and perilymph in the ears; and pleural, pericardial, and peritoneal fluids between serous membranes. - Two general “barriers” separate intracellular fluid, interstitial fluid, and blood plasma. ↳ 1. The plasma membrane of individual cells separates intracellular fluid from the surrounding interstitial fluid. You learned in anatomy and physiology that the plasma membrane is a selectively permeable barrier: It allows some substances to cross but blocks the movement of other substances. In addition, active transport pumps work continuously to maintain different concentrations of certain ions in the cytosol and interstitial fluid. 2.= Blood vessel walls divide the interstitial fluid from blood plasma. Only in capillaries, the smallest blood vessels, are the walls thin enough and leaky enough to permit the exchange of water and solutes between blood plasma and interstitial fluid. The body is in fluid balance when the required amounts of water and solutes are present and are correctly proportioned among the various compartments. Water is by far the largest single component of the body, making up 45–75% of total body mass, depending on age and gender. A Self-regulated Learning Module 19 (Source: Tortora, G. J. & Derrickson, B. (2014). Principles of Anatomy & Physiology. 14th ed. New Jersey, USA: John Wiley & Sons, Inc.) The processes of filtration, reabsorption, diffusion, and osmosis allow continual exchange of water and solutes among body fluid compartments. Yet the volume of fluid in each compartment remains remarkably stable. Because osmosis is the primary means of water movement between intracellular fluid and interstitial fluid, the concentration of solutes in these fluids determines the direction of water movement. Because most solutes in body fluids are electrolytes, inorganic compounds that dissociate into ions, fluid balance is closely related to electrolyte balance. Because intake of water and electrolytes rarely occurs in exactly the same proportions as their presence in body fluids, the ability of the kidneys to excrete excess water by producing dilute urine, or to excrete excess electrolytes by producing concentrated urine, is of utmost importance in the maintenance of homeostasis. E b. Sources of Body Water Gain and Loss The body can gain water by ingestion and by metabolic synthesis. The main sources of body water are ingested liquids (about 1600 mL) and moist foods (about 700 mL) absorbed from the gastrointestinal (GI) tract, which total about 2300 mL/day. The other source of water is metabolic water that is produced in the body mainly when electrons are accepted by oxygen during aerobic respiration and to a A Self-regulated Learning Module 20  smaller extent during dehydration synthesis reactions. Metabolic water gain accounts for only 200 mL/day. Daily water gain from these two sources totals about 2500 mL. Normally, body fluid volume remains constant because water loss equals water gain. Water loss occurs in four ways. Each day the kidneys excrete about 1500 mL in urine, the skin evaporates about 600 mL (400 mL through insensible perspiration— sweat that evaporates before it is perceived as moisture—and 200 mL as sweat), the lungs exhale about 300 mL as water vapor, and the gastrointestinal tract eliminates about 100 mL in feces. In women of reproductive age, additional water is lost in menstrual flow. On average, daily water loss totals about 2500 mL. The amount of water lost by a given route can vary considerably over time. For example, water may literally pour from the skin in the form of sweat during strenuous exertion. In other cases, water may be lost in diarrhea during a GI tract infection. - c. Regulation of Body Water Gain The volume of metabolic water formed in the body depends entirely on the level of aerobic respiration, which reflects the demand for ATP in body cells. When more ATP is produced, more water is formed. Body water gain is regulated mainly by the volume of water intake, or how much fluid you drink. An area in the hypothalamus known as the thirst center governs the urge to drink. When water loss is greater than water gain, dehydration—a decrease in volume and an increase in osmolarity of body fluids—stimulates thirst. When body mass decreases by 2% due to fluid loss, mild dehydration exists. A decrease in blood volume causes blood pressure to fall. This change stimulates the kidneys to release renin, which promotes the formation of angiotensin II. Increased nerve impulses from osmoreceptors in the hypothalamus, triggered by increased blood osmolarity, and increased angiotensin II in the blood both stimulate the thirst center in the hypothalamus. Other signals that stimulate thirst come from (1) neurons in the mouth that detect dryness due to a decreased flow of saliva and (2) baroreceptors that detect lowered blood pressure in the heart and blood vessels. As a result, the sensation of thirst increases, which usually leads to increased fluid intake (if fluids are available) and restoration of normal fluid volume. Overall, fluid gain balances fluid loss. Sometimes, however, the sensation of thirst does not occur quickly enough or access to fluids is restricted, and significant dehydration ensues. This happens most often in elderly people, in infants, and in those who are in a confused mental state. When heavy sweating or fluid loss from diarrhea or vomiting occurs, it is wise to start replacing body fluids by drinking fluids even before the sensation of thirst occurs. d. Regulation of Water and Solute Loss Even though the loss of water and solutes through sweating and exhalation increases during exercise, elimination of excess body water or solutes occurs mainly by control of their loss in urine. The extent of urinary salt (NaCl) loss is the main factor that determines body fluid volume. The reason for this is that “water follows solutes” in osmosis, and the two main solutes in extracellular fluid (and in urine) are A Self-regulated Learning Module 21 sodium ions (Na+) and chloride ions (Cl-). In a similar way, the main factor that determines body fluid osmolarity is the extent of urinary water loss. Because our daily diet contains a highly variable amount of NaCl, urinary excretion of Na+ and Cl- must also vary to maintain homeostasis. Hormonal changes regulate the urinary loss of these ions, which in turn affects blood volume. The increased intake of NaCl produces an increase in plasma levels of Na+ and Cl- (the major contributors to osmolarity of extracellular fluid). As a result, the osmolarity of interstitial fluid increases, which causes movement of water from intracellular fluid into interstitial fluid and then into plasma. Such water movement increases blood volume. The three most important hormones that regulate the extent of renal Na+ and Cl- reabsorption (and thus how much is lost in the urine) are angiotensin II, aldosterone, and atrial natriuretic peptide (ANP). When your body is dehydrated, angiotensin II and aldosterone promote urinary reabsorption of Na+ and Cl- (and water by osmosis with the electrolytes), conserving the volume of body fluids by reducing urinary loss. An increase in blood volume, as might occur after you finish one or more supersized drinks, stretches the atria of the heart and promotes release of atrial natriuretic peptide. ANP promotes natriuresis, elevated urinary excretion of Na+ (and Cl-) followed by water excretion, which decreases blood volume. An increase in blood volume also slows release of renin from juxtaglomerular cells of the kidneys. When renin level declines, less angiotensin II is formed. Decline in angiotensin II from a moderate level to a low level increases glomerular filtration rate and reduces Na +, Cl- , and water reabsorption in the kidney tubules. In addition, less angiotensin II leads to lower levels of aldosterone, which causes reabsorption of filtered Na+ and Cl- to slow in the renal collecting ducts. More filtered Na+ and Cl- thus remain in the tubular fluid to be excreted in the urine. The osmotic consequence of excreting more Na+ and Cl- is loss of more water in urine, which decreases blood volume and blood pressure. The major hormone that regulates water loss is antidiuretic hormone (ADH). This hormone, also known as vasopressin, is produced by neurosecretory cells that extend from the hypothalamus to the posterior pituitary. In addition to stimulating the thirst mechanism, an increase in the osmolarity of body fluids stimulates release of ADH. ADH promotes the insertion of water-channel proteins (aquaporin-2) into the apical membranes of principal cells in the collecting ducts of the kidneys. As a result, the permeability of these cells to water increases. Water molecules move by osmosis from the renal tubular fluid into the cells and then from the cells into the bloodstream. The result is production of a small volume of very concentrated urine. Intake of water in response to the thirst mechanism decreases the osmolarity of blood and interstitial fluid. Within minutes, ADH secretion shuts down, and soon its blood level is close to zero. When the principal cells are not stimulated by ADH, aquaporin-2 molecules are removed from the apical membrane by endocytosis. As the number of water channels decreases, the water permeability of the principal cells’ apical membranes fall, and more water is lost in the urine. Under some conditions, factors other than blood osmolarity influence ADH secretion. A large decrease in blood volume, which is detected by baroreceptors (sensory neurons that respond to stretching) in the left atrium and in blood vessel walls, also stimulates ADH release. In severe dehydration, glomerular filtration rate A Self-regulated Learning Module 22  decreases because blood pressure falls, so that less water is lost in the urine. Conversely, the intake of too much water increases blood pressure, causing the rate of glomerular filtration to rise and more water to be lost in the urine. Hyperventilation (abnormally fast and deep breathing) can increase fluid loss through the exhalation of more water vapor. Vomiting and diarrhea result in fluid loss from the GI tract. Finally, fever, heavy sweating, and destruction of extensive areas of the skin from burns can cause excessive water loss through the skin. In all of these conditions, an increase in ADH secretion will help conserve body fluids. Summary of Factors that Maintain Body Water Balance Factor Mechanism Effect Thirst center in Stimulates desire to drink fluids. Water gained if thirst is quenched. hypothalamus Angiotensin II Stimulates secretion of Reduces loss of water in aldosterone. urine. Aldosterone By promoting urinary Reduces loss of water in reabsorption of Na+ and Cl-, urine. increases water reabsorption via osmosis. Atrial natriuretic Promotes natriuresis, elevated Increases loss of water in urinary excretion of Na+ (and urine. peptide (ANP) Cl-), accompanied by water. Antidiuretic Promotes insertion of water- Reduces loss of water in channel proteins (aquaporin-2) urine. hormone into apical membranes of (ADH), also principal cells in collecting ducts known as of kidneys. As a result, water permeability of these cells vasopressin increases and more water is reabsorbed. 2 b. Movement of Water between Body Fluid Compartments Normally, cells neither shrink or swell because intracellular and interstitial fluids have the same osmolarity. Changes in the osmolarity of interstitial fluid, however, cause fluid imbalances. An increase in the osmolarity of interstitial fluid draws water out of cells, and they shrink slightly. A decrease in the osmolarity of interstitial fluid, by contrast, causes cells to swell. Changes in osmolarity most often result from changes in the concentration of Na+. A Self-regulated Learning Module 23  A decrease in the osmolarity of interstitial fluid, as may occur after drinking a large volume of water, inhibits secretion of ADH. Normally, the kidneys then excrete a large volume of dilute urine, which restores the osmotic pressure of body fluids to normal. As a result, body cells swell only slightly, and only for a brief period. But when a person steadily consumes water faster than the kidneys can excrete it (the maximum urine flow rate is about 15 mL/ min) or when renal function is poor, the result may be water intoxication, a state in which excessive body water causes cells to swell dangerously. If the body water and Na+ lost during blood loss or excessive sweating, vomiting, or diarrhea is replaced by drinking plain water, then body fluids become more dilute. This dilution can cause the Na+ concentration of plasma and then of interstitial fluid to fall below the normal range. When the Na + concentration of interstitial fluid decreases, its osmolarity also falls. The net result is osmosis of water from interstitial fluid into the cytosol. Water entering the cells causes them to swell, producing convulsions, coma, and possibly death. To prevent this dire sequence of events in cases of severe electrolyte and water loss, solutions given for intravenous or oral rehydration therapy (ORT) include a small amount of table salt (NaCl). [ c. Electrolytes in Body Fluids The ions formed when electrolytes dissolve and dissociate serve four general functions in the body. (1) Because they are largely confined to particular fluid compartments and are more numerous than nonelectrolytes, certain ions control the osmosis of water between fluid compartments. (2) Ions help maintain the acid– base balance required for normal cellular activities. (3) Ions carry electrical current, which allows production of action potentials and graded potentials. (4) Several ions serve as cofactors needed for optimal activity of enzymes. F Concentrations of Electrolytes in Body Fluids To compare the charge carried by ions in different solutions, the concentration of ions is typically expressed in units of milliequivalents per liter (mEq/liter). These units give the concentration of cations or anions in a given volume of solution. One equivalent is the positive or negative charge equal to the amount of charge in one mole of H+; a milliequivalent is one one-thousandth of an equivalent. Recall that a mole of a substance is its molecular weight expressed in grams. For ions such as sodium (Na+), potassium (K+), and bicarbonate (HCO3), which have a single positive or negative charge, the number of mEq/liter is equal to the number of mmol/liter. For ions such as calcium (Ca2+) or phosphate (HPO42-), which have two positive or negative charges, the number of mEq/liter is twice the number of mmol/liter. The chief difference between the two extracellular fluids—blood plasma and interstitial fluid—is that blood plasma contains many protein anions, in contrast to interstitial fluid, which has very few. Because normal capillary membranes are virtually impermeable to proteins, only a few plasma proteins leak out of blood vessels into the interstitial fluid. This difference in protein concentration is largely responsible for the blood colloid osmotic pressure exerted by blood plasma. In other respects, the two fluids are similar. A Self-regulated Learning Module 24  The electrolyte content of intracellular fluid differs considerably from that of extracellular fluid. In extracellular fluid, the most abundant cation is Na+, and the most abundant anion is Cl-. In intracellular fluid, the most abundant cation is K+, and the most abundant anions are proteins and phosphates (HPO42-). By actively transporting Na+ out of cells and K+ into cells, sodium–potassium pumps (Na+–K+ ATPases) play a major role in maintaining the high intracellular concentration of K+ and high extracellular concentration of Na+. 6 Sodium Sodium ions (Na+) are the most abundant ions in extracellular fluid, accounting for 90% of the extracellular cations. The normal blood plasma Na_ concentration is 136–148 mEq/liter. As we have already learned, Na+ plays a pivotal role in fluid and electrolyte balance because it accounts for almost half of the osmolarity of extracellular fluid (142 of about 300 mOsm/liter). The Na+ level in the blood is controlled by aldosterone, antidiuretic hormone (ADH), and atrial natriuretic peptide (ANP). Aldosterone increases renal reabsorption of Na+. When the blood plasma concentration of Na+ drops below 135 mEq/liter, a condition called hyponatremia, ADH release ceases. Atrial natriuretic peptide increases Na+ excretion by the kidneys when the Na+ level is above normal, a condition called hypernatremia. · Chloride Chloride ions (Cl-) are the most prevalent anions in extracellular fluid. The normal blood plasma Cl- concentration is 95–105 mEq/ liter. Cl- moves relatively easily between the extracellular and intracellular compartments because most plasma membranes contain many Cl- leakage channels and antiporters. Chloride ions also are part of the hydrochloric acid secreted into gastric juice. ADH helps regulate Cl balance in body fluids because it governs the extent of water loss in urine. Processes that increase or decrease renal reabsorption of sodium ions (Na+) also affect reabsorption of chloride ions. G Potassium Potassium ions (K+) are the most abundant cations in intracellular fluid (140 mEq/liter). K+ plays a key role in establishing the resting membrane potential and in the repolarization phase of action potentials in neurons and muscle fibers; K+ also helps maintain normal intracellular fluid volume. When K+ moves into or out of cells, it often is exchanged for H+ and thereby helps regulate the pH of body fluids. The normal blood plasma K+ concentration is 3.5–5.0 mEq/liter and is controlled mainly by aldosterone. - Bicarbonate - Bicarbonate ions (HCO ) are the second most prevalent extracellular anions. 3 Normal blood plasma HCO3- concentration is 22–26 mEq/liter in systemic arterial blood and 23–27 mEq/liter in systemic venous blood. HCO3- concentration increases as blood flows through systemic capillaries because the carbon dioxide released by metabolically active cells combines with water to form carbonic acid; the carbonic acid then dissociates into H+ and HCO3- As blood flows through pulmonary capillaries, however, the concentration of HCO3- decreases again as carbon dioxide is exhaled. The kidneys are the main regulators of blood HCO3- concentration. A Self-regulated Learning Module 25  The intercalated cells of the renal tubule can either form HCO3- and release it into the blood when the blood level is low or excrete excess HCO3- in the urine when the level in blood is too high. G Calcium Because such a large amount of calcium is stored in bone, it is the most abundant mineral in the body. About 98% of the calcium in adults is located in the skeleton and teeth, where it is combined with phosphates to form a crystal lattice of mineral salts. In body fluids, calcium is mainly an extracellular cation (Ca2+). The normal concentration of free or unattached Ca2+ in blood plasma is 4.5–5.5 mEq/liter. Besides contributing to the hardness of bones and teeth, Ca2+ plays important roles in blood clotting, neurotransmitter release, maintenance of muscle tone, and excitability of nervous and muscle tissue. The most important regulator of Ca2+ concentration in blood plasma is parathyroid hormone (PTH). A low level of Ca2+ in blood plasma promotes release of more PTH, which stimulates osteoclasts in bone tissue to release calcium (and phosphate) from bone extracellular matrix. Thus, PTH increases bone resorption. Parathyroid & hormone also enhances reabsorption of Ca2+ from glomerular filtrate through renal tubule cells and back into blood, and increases production of calcitriol (the form of vitamin D that acts as a hormone), which in turn increases Ca2+ absorption from food in the gastrointestinal tract. Recall that calcitonin (CT) produced by the thyroid gland inhibits the activity of osteoclasts, accelerates Ca2+ deposition into bones, and thus lowers blood Ca2+ levels. + Phosphate About 85% of the phosphate in adults is present as calcium phosphate salts, which are structural components of bone and teeth. The remaining 15% is ionized. Three phosphate ions (H2PO4-, HPO42-, and PO43-) are important intracellular anions. At the normal pH of body fluids, HPO42- is the most prevalent form. Phosphates contribute about 100 mEq/liter of anions to intracellular fluid. HPO42- is an important buffer of H+, both in body fluids and in the urine. The normal blood plasma concentration of ionized phosphate is only 1.7–2.6 mEq/liter. The same two hormones that govern calcium (Ca2+) homeostasis—parathyroid hormone (PTH) and calcitriol—also regulate the level of HPO42- in blood plasma. In the kidneys, however, PTH inhibits reabsorption of phosphate ions while stimulating reabsorption of calcium ions (Ca2+) by renal tubular cells. Thus, PTH increases urinary excretion of phosphate and lowers blood phosphate level. Calcitriol promotes absorption of both phosphates and calcium (Ca2+) from the gastrointestinal tract. - Magnesium In adults, about 54% of the total body magnesium is part of bone matrix as magnesium salts. The remaining 46% occurs as magnesium ions (Mg2_) in intracellular fluid (45%) and extracellular fluid (1%). A Self-regulated Learning Module 26  Mg2+ is the second most common intracellular cation (35 mEq/liter). Functionally, Mg2+ is a cofactor for certain enzymes needed for the metabolism of carbohydrates and proteins and for the sodium–potassium pump. Mg2+ is essential for normal neuromuscular activity, synaptic transmission, and myocardial functioning. In addition, secretion of parathyroid hormone (PTH) depends on Mg2+. Normal blood plasma Mg2+ concentration is low, only 1.3–2.1 mEq/liter. Learn more Online! Overview of Fluid and Electrolyte Physiology: https://www.youtube.com/watch?v=raW6b5kQHPY C. LABORATORY 1. LABORATORY SAFETY (Adapted from Safety in Academic Chemistry Laboratories, prepared by the American Chemical Society Committee on Chemical Safety). Source: https://drive.google.com/file/d/1OIl5Rj4dm6- z4DwmZ8uLU9flV_tQheOq/view?usp=sharing In any clinical setting or laboratory course, familiarity with the fundamentals of laboratory safety is of vital importance. A laboratory room can be a dangerous place in which to work. Understanding potential hazards will eliminate if not to decrease untoward hazards. Included in this manual are notes or cautions that point out some specific hazards and warnings. It is your responsibility, together with your Instructor, to make sure that all laboratory works is carried out in a safe manner. Your laboratory instructor will advise you of the specific rules for your laboratory. The following list of safety guidelines should be strictly observed at all times while in the laboratory room or when doing activities: a. SAFETY GUIDELINES 1) Always ware approved safety glasses or goggles. This sort of eye protectors must be worn at all times when inside the laboratory. Even if you are not actually carrying out an experiment, a person near you might have an accident that could endanger your eyes hence, eye protection is essential. 2) Keep in mind the location of Eyewash Facilities. If there are eyewash fountains (or sinks fitted with flexible hose) in your laboratory, you should determine which one is nearest to you before you start to work. In case any chemicals enter your eyes, go immediately to the eyewash fountain and flush your eyes and face with large amounts of water. b. FIRES 1) Use care with open flames in the laboratory. Because a laboratory course always deals with flammable substances, the danger of fire is frequently present. Because of this danger, exercise supreme caution when you light matches ore use any open flame. DO NOT PLAY WITH OPEN FLAME. A Self-regulated Learning Module 27  2) Learn the location of fire extinguishers and fire showers. In case of fire, you should learn immediately where the nearest fire extinguisher and shower rooms are, you should know how these safety devices are operated, particularly the fire extinguisher. If there is fire, the best advice is to get away from it and let the instructor or laboratory assistant take care of it. DON’T panic. Should your clothing catch fire, DO NOT RUN! Walk purposely towards the fire shower station or the nearest sink hose. Running will fan the flames and intensify it. c. SOLVENTS: THEIR HAZARDS 1) Avoid contact with organic solvents and corrosive chemicals. It is essential to remember that most organic solvents are flammable (e.g. ethyl alcohol, benzene, acetone, etc.) and will burn if they are exposed to an open flame or a match. Corrosive chemicals, such as Sulphuric acid, are just as dangerous, but manifest their hazardous nature in other, subtler ways. Handle them with care. MINIMIZE YOUR EXPOSURE. Minimize any direct exposure to organic solvents and treat them with respect. The laboratory room should be well ventilated. Normal cautious handling of solvents should not cause any health problem. Evaporate volatile solutions in a fume hood. Another sensible precaution is to wear polyethylene gloves or surgical gloves when working with solvents. 2) If you are pregnant, you may want to consider taking this course at a later time. Some exposure to organic fumes is inevitable, and any possible risk to an unborn baby should be avoided. 3) Do not breath solvent vapors. If you want to check the odor of a substance you should pass a stopper or spatula moistened with the substance (if it is a liquid) under your nose. Alternatively, you may hold the substance away from you and waft the vapors toward you with your hand. YOU SHOULD NEVER HOLD YOUR NOSE OVER THE CONTAINER AND INHALE DEEPLY. d. WASTE DISPOSAL 1) Do not place any inorganic and organic liquids or solids into sinks; use waste containers. Many chemicals especially organic substances are toxic, flammable, and difficult to degrade, it is not acceptable to dispose organic solvents or solids by pouring them down the sink. The appropriate disposal method for wastes is to place them into appropriately labelled wastes containers and they should be disposed of safely either by incineration or by burial in a designated hazardous-waste dump by your particular laboratory personnel. NONHAZARODUS SOLIDS such as paper, plastics and corks can be placed into an ordinary waste basket or trashcan. BROKEN GLASSWARE should be put into a container specifically designated for broken glassware. ORGANIC SOLIDS AND INORGANIC SOLIDS that are not turned in or any other solids should be disposed of in the container designated for each of them. HALOGENATED and NON-HALOGANATED SOLVENTS should be disposed of in the container designated for each of them. STRONG INORGANIC ACIDS AND BASES. Strong acids such as hydrochloric, Sulphuric, and nitric acid and strong bases such as sodium and potassium hydroxide should be neutralized, diluted with water, and poured down the drain. A Self-regulated Learning Module 28  HEAVY METALS. Many heavy metal ions such as mercury and chromium are highly toxic and should be disposed of into specifically designated waste containers. e. USE OF FLAMES. Check to see whether anyone in your vicinity is using flammable solvents before you ignite any open flame. If someone is using a flammable solvent, move to a safer location before you light your flame. f. INADVERTENTLY MIXED CHEMICALS. To avoid unnecessary hazards of fire and explosion, NEVER POUR EXTRA REAGENT BACK INTO A STOCK BOTTLE. There is always a chance that you may accidentally pour back some foreign substance that will react explosively with the chemical in the stock bottle. Pouring reagents back into stock bottles is not only dangerous but it is also inconsiderate because you may introduce impurities that could spoil the experiment for the person using the stock reagent after you. This also means that you should not take more chemicals than you need. g. UNAUTHORIZED EXPERIMENTS, YOU SHOULD NEVER UNDERTAKE ANY UNAUTHORIZED EXPERIMENTS. The risk of an accident is high, particularly with an experiment that has not been completely checked to reduce the hazard. You should never work alone in the laboratory. The laboratory instructor or supervisor must always be present. h. FOOD IN THE LABORATORY. Because all chemicals are potentially toxic, you should avoid accidentally ingesting any toxic substance; therefore, never eat or drink any food in the laboratory. There is always the possibility that whatever you are eating or drinking may become contaminated with a potentially hazardous material. i. CLOTHING. YOU SHOULD ALWAYS WEAR SHOES IN THE LABORATORY. Open- toed shoes or sandals offer inadequate protection against spilled chemicals or broken glass. To protect yourself and your clothing, it is advisable to wear a full-length laboratory gown or apron. Do not wear your best clothing in the laboratory because some chemicals can make holes or permanent stains on your clothing. Lastly, you should tie back hair that is shoulder length or longer, especially if you are working with a burner. j. FIRST AID: CUTS, MINOR BURNS, AND ACID OR BASE BURNS NOTE: any injury, no matter how small, must be reported to your laboratory instructor immediately. A Self-regulated Learning Module 29 Name:_____________________________________________________Score:____________ Group No. and Schedule:_____________________________________Date:_____________ Activity No. 1 FAMILIARITY WITH COMMON LABORATORY EQUIPMENT AND APPARATUS I. OBJECTIVE The students are expected to identify and enumerate the functions of each common laboratory equipment and apparatus so that accidents will be minimized or avoided. II. DISCUSSION Majority of experimental techniques involve the use of special apparatus and equipment. Hence, it is just proper that you must be familiar with these before you can properly use them. In this exercise, you will be introduced to common equipment that will be using during our laboratory class. You should be able to choose properly the equipment and apparatus you will be needing in each of the activities and experiments you will be performing. III. MATERIALS Bunsen burner, tripod, 250 ml beaker, graduated cylinder, pipette, medicine dropper, test tube, test tube rack, test tube brush, test tube holder, wire gauze, evaporating dish, stirring rod, triple balance beam Pencil, pen, ruler, and other drawing materials IV. PROCEDURE 1. Draw the equipment and/or apparatus assigned to your group. 2. Give the use of each equipment or apparatus. 3. Refer to the rubric below: Criteria Highest Possible Score Actual Score Drawing looks similar to what 10 was observed and/or taught. Drawing is accurately 20 labeled, including the use. Drawing is legible and large 20 enough to see all details. TOTAL 50 A Self-regulated Learning Module 30 DRAWING USE A Self-regulated Learning Module 31 A Self-regulated Learning Module 32 A Self-regulated Learning Module 33 A Self-regulated Learning Module 34 A Self-regulated Learning Module 35 A Self-regulated Learning Module 36 A Self-regulated Learning Module 37 A Self-regulated Learning Module 38 A Self-regulated Learning Module 39 A Self-regulated Learning Module 40 Name:_____________________________________________________Score:____________ Group No. and Schedule:_____________________________________Date:_____________ Activity No. 2 THE GAS BURNER I. OBJECTIVE The students are expected to identify the different parts of a Bunsen Burner and learn how to manipulate them. II. DISCUSSION The Bunsen burner and Trill Burners are designed to furnish heat in the laboratory by burning gaseous fuels. The burner is so constructed as to allow control of both gas and air flow before combustion. This is necessary because variations in the ratio of air and gas will affect the type of flame produced by the burner. III. MATERIALS Bunsen burner, evaporating dish, crucible tong, match, cardboard, copper wire Pencil. Coloring material, ruler IV. PROCEDURE 4. Parts of the Burner Examine the burner by dismantling and labeling each part, cleaning the parts and reassembling it. The following parts may be identified: a. The Base, which supports the burner. b. The Gas inlet, where the fuel is admitted. c. The Barrel, where the gas and air are mixed. d. The gas regulator, which regulates the gas supply. e. The air holes, which controls the passage of air. 5. Lighting the burner A. Controlling the amount of air a. Light the burner by introducing a lighted match at the tip of the barrel then turn on the gas outlet (gas regulator for Tirril burner). Describe the type of flame produced according to color and size. b. With the use of a crucible tong, hold a clean and dry evaporating dish over the flame. Observe what is produced at the bottom of the dish. Record observation. c. Gradually open the air holes and note down the changes in the color, size, and sound of flame. d. Clean the evaporating dish by wiping it with cloth. Use soap and water if necessary. Place the clean and dry evaporating dish over the flame with the use of crucible tong. Observe what is produced in the bottom of the dish. B. Controlling the gas and air mixture a. Close the air holes and turn off the gas regulator. b. Light the Bunsen burner by regulating the gas control valve of the outlet. c. Observe (based on the color) what type of flame is produced. C. Determining the flame temperature a. Light the burner and after obtaining the optimum adjustment, observe the distinct zones of the non-luminous flame. Determine the hottest region of the flame by A Self-regulated Learning Module 41  holding a piece of copper wire in the different part of the flame (use a different piece of copper wire for each region). Note the time (in seconds) the wire becomes red hot. Record the time in the following regions: Top of the flame: Top of the inner cone: Within the inner cone: b. Hold an unused and unlighted match stick at the different regions of the flame (use a different match stick for each region). Note the time (in seconds) the match is lighted. c. Moisten one piece of cardboard and with a tong hold it vertically across the top of the barrel until it starts to char. Make sure that the bottom of the cardboard is resting on top of the barrel. Identify the different zones in the cardboard. D. Back flashing or striking back a. Fully open the air holes of your burner b. Hold a lighted match at the top of the barrel and slowly turn on the gas regulator (use the control valve of the gas outlet for the Bunsen burner). The flame strikes back and burns the base of the burner. This happens when there is too much air admitted. Striking back or back flashing is dangerous because it releases poisonous gases and causes severe burns in the fingers if the burner is touched. c. Turn off the gas supply at once and let the burner cool A Self-regulated Learning Module 42 Name:_____________________________________________________Score:____________ Group No. and Schedule:_____________________________________Date:_____________ Activity No. 3 COMMON LABORATORY TECHNIQUES AND OPERATIONS I. OBJECTIVE The students are expected to develop skills in using some common laboratory equipment and apparatus and to acquire the correct technique and skills in performing laboratory procedures. II. DISCUSSION As students of biochemistry, it is vital to be familiar with the correct techniques in doing laboratory operations and procedures. In this exercise, the operations and procedures are studied and correctly practiced. III. MATERIALS Glass tubing, triangular file, graduated cylinder, pipette, rubber bulb aspirator, beaker, weighing balance, stirring rod, test tube, test tube holder, burner, tripod, wire gauze, funnel evaporating dish and a filter paper. FCl3 (Ferric chloride), NaOH (ammonium hydroxide) solution. Sand, match IV. PROCEDURE A. Some Common laboratory operations 6. Transferring of liquids To transfer a liquid from one container to another, observe the following: Procedure Competently Done with Not Done Done Assistance (0) (2) (1) a. Hold a stirring rod against the lip of the container with the liquid. b. Pour the liquid down the rod which should touch the inside wall of the receiving vessel c. Transfer only the amount needed. Do not return unused chemicals to the reagent bottle. 7. Transferring a solid (for the teacher to demo and discussion) Procedure Competently Done with Not Done Done Assistance (0) (2) (1) A Self-regulated Learning Module 43  a. Read the label on the bottle twice to be sure of using the correct reagent. b. Remove the cover and set it on the bench, inner side facing up. c. Hold the bottle in a tilted position and roll back and forth until the desired amount has been dispensed. d. Do not dispense more reagent than needed. e. After using, cover the bottle tightly. B. Experimental procedures 1. Heating in a test tube Procedure Competently Done with Not Done Done Assistance (0) (2) (1) a. Fill the test tube with water to about 1/3 full and using a test tube holder. b. Hold the test tube in a slanting position when heating. c. Use low flame and keep the test tube in constant motion. d. Never point the test tube to anyone. Do not heat the tube directly at the bottom. 2. Heating in a beaker Procedure Competently Done with Not Done Done Assistance (0) (2) (1) a. Half-fill a beaker with water. b. Rest the beaker on a tripod with wire gauze over it A Self-regulated Learning Module 44  c. Heat the beaker until boiling. d. Lower the flame after the water boils. 3. Decantation Procedure Competently Done with Not Done Done Assistance (0) (2) (1) a. Place 5 grams of sand in a beaker containing 100 ml of tap water. b. Stir with a glass rod and let it stand for 5 minutes. c. Carefully pour the water off without carrying the sand with it. 4. Precipitation Procedure Competently Done with Not Done Done Assistance (0) (2) (1) a. To 5 ml of 10% ferric chloride (FeCl3) solution add 10 ml of 10% sodium hydroxide (NaOH). b. Save this product for the succeeding procedures. 5. Filtration Procedure Competently Done with Not Done Done Assistance (0) (2) (1) a. Pour the mixture (obtained from precipitation) through a funnel with a filter paper. b. Save the filtrate for the next procedure. 6. Evaporation A Self-regulated Learning Module 45  Procedure Competently Done with Not Done Done Assistance (0) (2) (1) a. Transfer the filtrate (obtained from the filtration) to an evaporating dish. b. Place the dish on a tripod with a wire gauze. c. Heat (use a low flame) to dryness until all liquid has evaporated. A Self-regulated Learning Module 46  CHECK FOR FACTS AND UNDERSTANDING Instructions: Answer what is being asked. Use an additional clean paper if needed. You will be graded based on the rubric below. The same rubric will apply to the assessments with the same activity on the subsequent Check for Facts and Understanding. Criteria/Score 3 2 1 (per question) Accurateness and Answer is perfectly Answer is somewhat Answer is neither Completeness accurate and accurate and slightly accurate nor completely addresses addresses what is complete. what is being asked. being asked. Grammar and Answer is Answer has minimal Answer has Punctuations grammatically correct grammatical error incomplete thoughts. and with and with one to two proper/appropriate inappropriate use of punctuation punctuation marks marks. (missed punctuations). Readability Handwriting legible. Handwriting is Handwriting is somewhat legible. unreadable. Subtotal TOTAL 1. Differentiate cations from anions. (9 points) _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 2. What is the main difference between an ionic bond and a covalent bond? (9 points) _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 3. Compare the properties (i.e. valence shell, number of protons, and strength) of ionic, covalent, and hydrogen bonds. (9 points) A Self-regulated Learning Module 47  _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 4. What are the important functions of water in the body? (9 points) _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 5. What is the approximate volume of each of your body fluid compartments? (9 points) _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 6. Name three important extracellular electrolytes and three important intracellular electrolytes and indicate how each is regulated. (9 points) ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ A Self-regulated Learning Module 48  UNIT II. BIOCHEMISTRY OF THE CELL Objectives After Studying this unit, you should be able to: a. name and describe the three main parts of a cell; b. describe the structure and functions of deoxyribonucleic acid (DNA), ribonucleic acid (RNA); c. describe the molecules involved and the mechanism of RNA synthesis; d. explain how eukaryotic DNA-dependent RNA polymerases, in collaboration with an array of specific accessory factors, can differentially transcribe genomic DNA to produce specific messenger RNA (mRNA) precursor molecules, and e. describe the structure of eukaryotic mRNA precursors, which are highly modified internally and at both termini. A. REVIEW ON PARTS OF THE CELL 1. The plasma membrane forms the cell’s flexible outer surface, separating the cell’s internal environment (everything inside the cell) from the external environment (everything outside the cell). It is a selective barrier that regulates the flow of materials into and out of a cell. This selectivity helps establish and maintain the appropriate environment for normal cellular activities. The plasma membrane also plays a key role in communication among cells and between cells and their external environment. Structure of the Plasma Membrane a. The Lipid Bilayer The basic structural framework of the plasma membrane is the lipid bilayer, two back-to-back layers made up of three types of lipid molecules—phospholipids,