Chapter 2 & 24- Chemical Composition of the Human Body
Chapter 2 & 24- Chemical Composition of the Human Body KNR 182
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This 54 page Class Notes was uploaded by Christina on Sunday August 30, 2015. The Class Notes belongs to KNR 182 at Illinois State University taught by Dr. Rinaldi-MIles in Summer 2015. Since its upload, it has received 212 views. For similar materials see Human Anatomy and Physiology II (lecture) in Kinesiology at Illinois State University.
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Date Created: 08/30/15
HUMAN ANATOMY amp PHYSIOLOGY KNR 182 Chemical Composition of the Human Body Chapter 2amp24 Chemical Composition of Human Body Why chemistry in an anatomy course AEvery physiological process that your body does there are chemical reactions that underly everything You must understand chem To understand how these physiological functions occur YouTube Incredible Human Machine 1 9 Levels of Structural Organization within the Human B 4 WA Isl za ga SulTafomic Organ amp Particles Molecules Organelles Tissue Systems Matter Anything that has mass and occupies space All matter such as solids liquids and gases is composed of atoms regardless of state Therefore the atom is considered to be the basic building block of matter Composition of Matter Atoms Unique building blocks for each element Elements cant be broken down Each has unique properties Physical properties Are detectable with our senses or are measurable Chemical properties How atoms interact bond with one another We are interested in bonding behavior because it dictates how structures are built up and are broken down Atomic symbol one or twoletter chemical shorthand for each element Composition of Matter Elements Cannot be broken down by ordinary Chemical means Examples Oxygen carbon gold silver copper and iron Major Elements of the Human Body Oxygen O Carbon C Hydrogen H Nitrogen N gt About 96 of body mass Each play a unique roll in the body Oxygen allows for cellular respiration Hydrogen plays a role an balancing your body s pH Nitrogen is found in proteins and amino acids Carbon is found in all organic compounds Elements versus Atoms An element is a name for a specific substance Gold is an element An atom is the smallest possible piece of that substance that retains all its properties A single atom of gold has 79 protons roughly 117 neutrons and 79 electrons Atoms Composed of subatomic particles Nucleus in nucleus is protons and neutrons The shells have electrons The nucleus is the center of the atom made up of protons and neutrons has a positive charge Circling the nucleus are electrons which have a negative charge You Tube Basic Atomic Structure Atomic Structure Determined by numbers of subatomic particles Neutrons No charge Mass 1 atomic mass unit amu Protons Positive charge Mass 1 amu Electrons Orbit nucleus Equal in number to protons in atom Negative charge 12000 the mass of a proton 0 amu Identifying Elements Atoms of different elements contain different numbers of subatomic particles Compare hydrogen helium and lithium Hydrogen 1 p OnAO 1e Helium 2p 2nquot0 2e Lithium 3p 4nquotO 3e Example on the next slide Proton O Neutron 0 Electron Hydrogen H Helium He Lithium Li 1p 0n 1939 2p 2n 2939 3p 4n 3939 Figure 22 Molecules and Compounds Most atoms combine chemically with other atoms to form molecules Molecule of that element two or more of the same atoms bonded together 2 molecule of hydrogen Molecule of a compound two or more different kinds of atoms bonded together H20 the compound water or a molecule of water Check your understanding An atom s nucleus contains PROTONS and NEUTRONS When you put different atoms of different elements together you get a COMPOUND Chemical Bonds Rule of Eights Electrons occupy up to seven electron shells energy levels around nucleus The number of electrons in the valence shell the outermost electron shell will dictate how many other atoms each atom can interact with The further away the electron is from the nucleus the weaker the attraction is The electrons stay in orbit due to attraction between protons and electrons Octet Rule the rule of eights 1St electron shell 2 bonding electrons 2nol electron shell 8 bonding electrons 3rOI electron shell 8 bonding electrons 4th electron shell 8 bonding electrons And so on The most you can have is 8 electrons in the 2nOI electron shell or higher Chemical Bonds How are atoms held together Through the presence of various types of chemical bonds It is an energy relationship between the electrons of the reacting atoms Made or broken within a trillionth of a second The number of electrons in the valence shell will dictate how many atoms that atom can interact with Chemical reactions are bonds being made or being broken Chemically Inert Elements Stable and unreactive Outermost electron shell valence shell is fully occupied or contains eight electrons NOT engaging in chemical reactions If the outer shell is full the atom is stableunreactive Ex helium and neon aka the Noble Gases Helium He Neon Ne 2p 2n0 2e 1053 lOnO 10e a Chemically inert elements valence shell complete Copynghl D 2001 Belgium Cumrnmgs an unprlnl ol Addlson Wesley Longrnan Inc Chemically Reactive Elements Outermost electron shell valence shell not fully occupied by electrons Tend to gain lose or share electrons form bonds with other atoms to achieve stability Ex hydrogen carbon oxygen and sodium Carbon can either give up or take on beause it has 4 electrons in its valence shell The most determinant of an atom s bonding behavior is the number of electrons in the valence shell b Chemically reactive elements Outermost energy level valence shell incomplete 4e Hydrogen H Carbon C 1 p Ono 1e 6p 6n 6e 1e oxygen 0 Sodium Na 8p 8n 8639 11p12n 11e Figure 25b Chemical Bonds Types of Chemical Bonds Ionic Bonds Formed by the transfer of a valence electron Aka an electron is given up taken on by a set of atoms Covalent Bonds Hydrogen Bonds Ionic Bonds Ions are formed by transfer of valence shell electrons between atoms Anions charge have gained one or more electrons electronegative Cations charge have lost one or more electrons Attraction of opposite charges results in an ionic bond wit m EEJEF quotE a 3 5 EHEEEE Sodium atom Na Chlorine atom Cl I Sodium ion Nat Chloride ion Cl I 11p12n 11e39 17p18n 17e39 Sodium chloride NaCl a Sodium gains stability by losing one electron and b After electron transfer the oppositely chlorine becomes stable by gaining one electron charged ions formed attract each other Figure 26ab Covalent Bonds Formed by sharing of two or more valence shell electrons Allows each atom to fill its valence shell at least part of the time Typically found in organic molecules especially the macronutrients Molecule of methane gas CH4 a Formation of four single covalent bonds carbon shares four electron pairs with four hydrogen atoms Carbon atoms atom Hydrogen Structural formula shows single bonds Figure 27a Hydrogen Bonds Attractive force between electropositive hydrogen of one molecule and an electronegative atom of another molecule More of an attraction than an actual bond Common between dipoles such as water Dipoles are molecules that have one end that is more positive and one end that is more negative ie H20 oxygen is electronegative and Hydrogens are electropositive how multiple water molecules are attracted to each other to produce surface tension Also act as intramolecular bonds holding a large molecule in a threedimensional shape More of an attraction than a bond Q h A water strider can walk on a pond because of the high surface tension of water a result of the combined strength of its hydrogen bonds Figure 210b So what Atoms amp chemical bonds who cares The combination of atoms and chemical bonds forms or makes molecules which are essential for life The human body is a chemical machine Chemical reactions form the basis for ife Levels of Structural Organization within the Human Bod 2 4 11 Islx51 RelA SulTatomic Organ amp Particles Molecules Organelles Tissue Systems Protons Qarbon Neutrons ydrogen Electrons Eitrogen QXygen Ehosphorus ulfur others Chemical reactions MOLECULES Molecules are formed when two or more atoms combine The combining of two or more atoms occurs due to chemical bonding between the atoms 2 Hydrogen 1 Oxygen H20 Water 12 Carbon 22 Hydrogen 11 Oxygen C12H22011 quot Chemical Reactions Occur when chemical bonds are formed rearranged or broken Represented as chemical equations Reactants on one side and products on the other Chemical equations contain Molecular formula for each reactant and product Relative amounts of reactants and products which should balance Chemical Equations H H gt H2 hydrogen gas reactants product 4H C gt CH4 methane Rate of Chemical Reactions Rate of reaction is influenced by T temperature gt T rate of reaction l particle size gt T rate T concentration of reactant gt T rate Catalysts T rate without being chemically changed Enzymes are biological catalysts A protein EX Chemical reaction in body The transport of CO2 to the lungs for expiration As part of a bicarbonate ion CO2 and H20 combine to form carbonic acid H2003 Dissociates under enzyme carbonic anhydrase in RBC Release hydrogen H and bicarbonate Ion HCOB CO2 H209 H2CO39 H MOST chemical reactions are reversible but not all Classes of Compounds Inorganic compounds Water salts and many acids and bases Do not contain carbon Organic compounds Contain carbon usually large and are covalently bonded Include Carbohydrates lipids proteins nucleic acids Covalent bonds like a paper clip holding two pieces of paper togethereasy to break apart Both inorganic and organic compounds play an equally important role in the body Carbon Electroneutral 4 electrons in its valence shell Helps form long chainlike structures because it can readily bond with so many elements Likes to share electrons rather than take ongive up electrons Organic compounds Many polymers chains of similar units monomers or building books Synthesized by dehydration synthesis Broken down by hydrolysis reactions Water 60 80 of the volume of living cells Blood plasma is 90 water Chemistry is a wet science because a majority of reactions occur in water Most abundant molecule in the body Most important inorganic compound in living organisms because of its properties Properties of Water High heat capacity Absorbs and releases relatively large amounts of heat with little temperature change Prevents sudden changes in temperature Because the body has a high heat capacity it allows for vital chemical reactions to continuously to occur in the body High heat of vaporization Evaporation requires large amounts of heat Useful cooling mechanism Properties of Water Polar solvent properties Dissolves and dissociates ionic substances Body s major transport medium Ex Water is a great solvent because it is polar O is Negative H is positive Water causes the other molecule to disassociate creating a solution This is why water is a great transport medium in the body Salt crystal Ions in solution Figure 212 Properties of Water Reactivity A necessary part of hydrolysis and dehydration synthesis reactions Cushioning Protects certain organs from physical trauma eg found in cerebrospinal fluid around the brain Electrolytes All ions charge are electrolytes Substances that conduct an electrical current in solution The electrolytes of greatest importance to cellular functions release sodium potassium calcium magnesium chloride sulfate phosphate bicarbonate and hydrogen ions Obtained from foods but some are from water and other beverages You should be able to receive a sufficient amount of electrolytes by responding to sensations of hunger and thirst Salts Ionic compounds that dissociate in water Contain cations other than H and anions other than OH Na plays specialized roles in body functions Water balance Conduction of nerve impulses Muscle contraction Acids and Bases Both are electrolytes Acids are proton hydrogen ion donors release H in solution HCI gt H or Bases are proton acceptors take up H from solution NaOH gt Na OH OH accepts an available proton H OH H gt H20 Bicarbonate ion HCO3 and ammonia NH3 are important bases in the body AcidBase Concentration Acid solutions contain H As H increases acidity increases Alkaline solutions contain bases eg OH As H decreases or as OH increases alkalinity increases more basic Measured using the pH scale pH AcidBase Concentration pH the negative logarithm of H in moles per liter Neutral solutions Pure water is pH neutral contains equal numbers of H and OH pH of pure water pH 7 H 10 7 M All neutral solutions are pH 7 pH AcidBase Concentration Acidic solutions T H l pH Acidic pH 0 699 pH scale is logarithmic a pH 5 solution has 10 times more H than a pH 6 solution Alkaline solutions 39 L H T stomach acid coffee milk b 39 soda bleach Alkaline basic pH 701 14 appleiuice blood w h 01 23456789011121314 4 67891011121314 2 esh acid water e a battery acid am tomato soap dram pure ram cleaner soft drinks laundry detergent AcidBase Homeostasis pH change interferes with cell function and may damage living ssue A slight change in pH can be fatal pH is regulated by kidneys lungs and buffers Kidneys Lungs when your body takes food and creates ATP a byproduct is CO2 buffers Buffers Mixture of compounds that resist pH changes Convert strong completely dissociated acids or bases into weak slightly dissociated ones Carbonic acidbicarbonate system Response to rise in pH H2C03 Hco H H donor Response to drop in pH H acceptor proton weak acid weak base Carbonic acid Bicarbonate ion hydrogen AcidBase lmbalances Chemical and physiological buffer systems ordinarily maintain the hydrogen ion concentration of body fluids within very narrow pH ranges Abnormal conditions may disturb the acidbase balance Homeostasis Copyright The McGrawHill Companies Inc Permission required for reproduction or display Acidosis Alkalosis pH scale Normal pH range Survival range 54 Check your understanding A buffer will release H ions if the blood pH rises
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