A&P Ch.2 Sum2023 PDF

Chapter 1 Major Themes of Anatomy and Physiology ANATOMY & PHYSIOLOGY The Unity of Form and Function Ninth Edition Kenneth S. Saladin © 2022 McGraw Hill. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribu...

Chapter 1 Major Themes of Anatomy and Physiology ANATOMY & PHYSIOLOGY The Unity of Form and Function Ninth Edition Kenneth S. Saladin © 2022 McGraw Hill. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw Hill.  Introduction Biochemistry The study of the molecules that compose living organisms Carbohydrates, fats, proteins, and nucleic acids Useful for understanding cellular structures, basic physiology, nutrition, and health © McGraw Hill 2  2.1 Atoms, Ions, and Molecules Expected Learning Outcomes: Identify the elements of the body from their symbols. Distinguish between elements and compounds. State the functions of minerals in the body. Explain the basis for radioactivity and the types and hazards of ionizing radiation. Distinguish between ions, electrolytes, and free radials. Define the types of chemical bonds. © McGraw Hill 3  The Chemical Elements 1 Element Simplest form of matter to have unique chemical properties Atomic number (for an element) Number of protons in the nucleus Periodic table Elements arranged by atomic number Elements represented by one- or two-letter symbols 24 elements have biological roles 6 elements = 98.5% of body weight Oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus Trace elements Present in minute amounts, but play vital roles © McGraw Hill 4  The Chemical Elements 2 Minerals Inorganic elements extracted from soil by plants and passed up food chain to humans Constitute about 4% of body weight Ca and P make up about 3% Remaining 1% is mainly Cl, Mg, K, Na, and S Important for body structure (Ca crystals in teeth, bones, etc.) Important for enzyme function Electrolytes are mineral salts needed for nerve and muscle function © McGraw Hill 5  Atomic Structure Nucleus—center of atom Protons: single (+) charge; mass = 1 atomic mass unit (amu) Neutrons: no charge; mass = 1 amu Atomic mass is approximately equal to total number of protons and neutrons Electrons—in concentric clouds surrounding nucleus Electrons: single (–) charge, very low mass An atom is electrically neutral, as number of electrons equals number of protons Valence electrons orbit in the outermost shell and determine chemical bonding properties of an atom © McGraw Hill 6  Bohr Planetary Models of Three Representative Elements Figure 2.1 © McGraw Hill 7  Isotopes and Radioactivity 1 Isotopes are varieties of an element that differ only in the number of neutrons Extra neutrons increase atomic weight Isotopes of an element are chemically similar because they have the same number of valence electrons Atomic weight (relative atomic mass) of an element accounts for the fact that an element is a mixture of isotopes Radioisotopes Unstable isotopes that decay and give off radiation Every element has at least one radioisotope © McGraw Hill 8  Ions, Electrolytes, and Free Radicals 1 Ion Charged particle (atom or molecule) with unequal number of protons and electrons Ionization Transfer of electrons from one atom to another Anion Particle that has a net negative charge (due to gain of electrons) Cation Particle that has a net positive charge (due to loss of electrons) Ions with opposite charges are attracted to each other © McGraw Hill 13  Ionization Figure 2.4 © McGraw Hill 14  Ions, Electrolytes, and Free Radicals 3 Free radicals Short-lived particles with an unusual number of electrons Produced by normal metabolic reactions, radiation, certain chemicals Trigger reactions that destroy molecules, and can cause cancer, death of heart tissue, and aging Antioxidants Chemicals that neutralize free radicals Superoxide dismutase (SOD) is an antioxidant enzyme in the body Selenium, vitamin E, vitamin C, and carotenoids are antioxidants obtained through the diet © McGraw Hill 16  Molecules and Chemical Bonds 1 Molecule Particle composed of two or more atoms united by a chemical bond Compound Molecule composed of two or more different elements Molecular formula Identifies constituent elements and how many atoms of each are present Structural formula Identifies location of each atom Isomers Molecules with identical molecular formula but different arrangements of atoms © McGraw Hill 17  Structural Isomers—Ethanol and Ethyl Ether Figure 2.5 © McGraw Hill 18  Molecules and Chemical Bonds 3 Chemical bonds Hold atoms together within a molecule, or attract one molecule to another Important types include ionic bonds, covalent bonds, hydrogen bonds, and van der Walls forces Ionic bond Attraction of a cation to an anion Easily broken by water Covalent bond Atoms share one or more pairs of electrons Single covalent bond: nuclei share 1 pair of electrons Double covalent bond: nuclei share 2 pairs of electrons © McGraw Hill 20  Single Covalent Bond Figure 2.6a © McGraw Hill 21  Double Covalent Bond Figure 2.6b © McGraw Hill 22  Molecules and Chemical Bonds 4 Covalent bond (continued) Nonpolar covalent bond: electrons shared equally Polar covalent bond: electrons shared unequally (spend more time near oxygen) © McGraw Hill 23  Nonpolar and Polar Covalent Bonds Figure 2.7 © McGraw Hill 24  Molecules and Chemical Bonds 5 Hydrogen bond Weak attraction between a slightly positive hydrogen atom in one molecule and a slightly negative oxygen or nitrogen atom in another atom Important to physiology Water molecules are attracted to each other by hydrogen bonds. Large molecules (DNA and proteins) are shaped in part by the formation of hydrogen bonds within them. © McGraw Hill 25  Hydrogen Bonding of Water Figure 2.8 © McGraw Hill 26  2.2 Water and Mixtures Expected Learning Outcomes: Define mixture and distinguish between mixtures and compounds. Describe the biologically important properties of water. Show how three kinds of mixtures differ from each other. Define acid and base and interpret the pH scale. Discuss some ways in which the concentration of a solution can be expressed, and the kinds of information we can derive from the different units of measure. © McGraw Hill 28  Water and Mixtures Mixtures Consist of substances that are physically blended but not chemically combined Body fluids are complex mixtures of chemicals Water Most mixtures in our bodies consist of chemicals dissolved or suspended in water Water is 50–75% of body weight Depends on age, sex, fat content, and so on © McGraw Hill 29  Water 1 Polar covalent bonds and a V-shaped molecule give water a set of properties that account for its ability to support life Solvency- ability to dissolve other chemicals Cohesion- clings to itself Adhesion- clings to different molcules Chemical reactivity Thermal stability © McGraw Hill 30  Water 3 Attractions to water molecules overpower the ionic bond in NaCl Water forms hydration spheres around each ion and the salt dissolves Water’s negative pole faces Na+, its positive pole faces Cl– Figure 2.9 © McGraw Hill 32  Water 5 Chemical reactivity Ability to participate in chemical reactions Water ionizes into H+ and OH– Water ionizes many other chemicals (acids and salts) Water is involved in hydrolysis and dehydration synthesis reactions © McGraw Hill 35  Water 6 Heat capacity Amount of heat needed to raise the temperature of 1 g of a substance by 1 °C Calorie (cal) Base unit of heat Amount of heat that raises the temperature of 1 g of water 1 °C Water’s thermal stability helps stabilize the internal temperature of the body Water has high heat capacity Hydrogen bonds resist temperature increases by inhibiting molecular motion Water is an effective coolant 1 ml of perspiration removes 500 calories © McGraw Hill 36  ICF, ECF, Blood Intracellular fluid (ICF)- the fluid within cells Extracellular fluid (ECF)- the fluid surrounding cells Plasma- fluid component of the blood Interstitial fluid- fluid surround cells not in the blood By OpenStax College - Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013., CC BY 3.0, © McGraw Hill 37 https://commons.wikimedia.org/w/index.php?curid=30148558  Acids, Bases, and pH 1 Acid Proton donor (releases H+ ions in water) Base Proton acceptor (accepts H+ ions or releases OH− ions) pH Measure of acidity derived from the molarity of H+ pH of 7.0 is neutral (H+ = OH−) pH of less than 7 is acidic (H+ > OH−) pH of greater than 7 is basic (OH− > H+) Maintaining normal (slightly basic) pH of blood is crucial for physiological functions Buffers are chemical solutions that resist changes in pH © McGraw Hill 42  2.3 Energy and Chemical Reactions Expected Learning Outcomes Define energy and work, and describe some types of energy. Understand how chemical reactions are symbolized by chemical equations. List and define the fundamental types of chemical reactions. Identify the factors that govern the speed and direction of a reaction. Define metabolism and its two subdivisions. Define oxidation and reduction, and relate these to changes in the energy content of a molecule. © McGraw Hill 47  Energy and Work 1 Energy Capacity to do work To do work means to move something All body activities are forms of work Potential energy Energy stored in an object, but not currently doing work Example: water behind a dam Chemical energy Potential energy in molecular bonds Free energy Potential energy available in a system to do useful work © McGraw Hill 48  Classes of Chemical Reactions 1 Chemical reaction Process in which a covalent or ionic bond is formed or broken Chemical equation Symbolizes the course of a chemical reaction Reactants (on left) → products (on right) © McGraw Hill 50  Classes of Chemical Reactions 3 Reversible reactions Can go in either direction under different circumstances Symbolized with double-headed arrow Example: CO2 + H2O ↔ H2CO3 ↔ HCO3− + H+ An important reaction in respiratory, urinary, and digestive physiology Law of mass action Direction of reaction determined by relative abundance of substances on either side of equation Equilibrium is reached when ratio of products to reactants is stable © McGraw Hill 55  Reaction Rates Reactions occur when molecules collide with enough force and correct orientation Reaction rates increase when: Concentration of reactants increases Temperature rises A catalyst is present Enzyme catalysts bind to reactants and hold them in orientations that facilitate the reaction Catalysts are not changed by the reaction and can repeat the process frequently © McGraw Hill 56  Metabolism, Oxidation, and Reduction 1 Metabolism All chemical reactions of the body Catabolism Energy-releasing (exergonic) decomposition reactions Breaks covalent bonds Produces smaller molecules Anabolism Energy-storing (endergonic) synthesis reactions Requires energy input Example: production of protein or fat Catabolism and anabolism are inseparably linked Anabolism is driven by energy released by catabolism. © McGraw Hill 57  2.4 Organic Compounds Expected Learning Outcomes: Explain why carbon is especially well suited to serve as the structural foundation of many biological molecules. Identify some common functional groups of organic molecules from their formulae. Discuss the relevance of polymers to biology and explain how they are formed and broken by dehydration synthesis and hydrolysis. Discuss the types and functions of carbohydrates, lipids, and proteins. Explain how enzymes function. Describe the structure, production, and function of ATP. Identify other nucleotide types and their functions and the principal types of nucleic acids. © McGraw Hill 60  Carbon Compounds and Functional Groups 1 Organic chemistry The study of compounds containing carbon Four categories of carbon compounds: Carbohydrates Lipids Proteins Nucleic acids © McGraw Hill 61  Carbon Compounds and Functional Groups 2 Carbon has four valence electrons Can form four covalent bonds with other atoms Carbon atoms bind readily with each other to form carbon backbones Form long chains, branched molecules, and rings Readily bond with hydrogen, oxygen, nitrogen, sulfur, and other elements Functional groups Small clusters of atoms attached to carbon backbone Determine many of the properties of organic molecules Examples: hydroxyl, methyl, carboxyl, amino, phosphate © McGraw Hill 62  Functional Groups of Organic Molecules Figure 2.13 © McGraw Hill 63  Monomers and Polymers 1 Macromolecules Very large organic molecules with high molecular weights Polymers Macromolecules made of a repetitive series of identical or similar subunits (monomers) Example: starch is a polymer of about 3,000 glucose monomers Polymerization Joining monomers to form a polymer © McGraw Hill 64  Monomers and Polymers 2 Dehydration synthesis (condensation) Monomers covalently bind together to form a polymer A hydroxyl (-OH) group is removed from one monomer, and a hydrogen (-H) from another Water produced as a by-product Hydrolysis The opposite of dehydration synthesis Splitting a polymer in monomers by the addition of water Enzyme helps break the covalent bond that links two monomers together A water molecule ionizes into OH- and H+ OH- is added to one monomer H+ is added to the other monomer © McGraw Hill 65  Dehydration Synthesis and Hydrolysis Reactions Figure 2.14 © McGraw Hill 66  Carbohydrates 1 Carbohydrates are hydrophilic organic molecules Examples: sugars and starches 2:1 ratio of hydrogen to oxygen General formula: (CH2O)n, n = number of carbon atoms Glucose, n = 6, so formula is C6H12O6 Names of carbohydrates often built from the root “sacchar-” and the suffix “-ose” both meaning sugar, sweet © McGraw Hill 67  Carbohydrates 2 Monosaccharides Simplest carbohydrates Monomers Three important monomers are glucose, galactose, and fructose Produced by digestion of more complex carbohydrates Glucose is blood sugar All three have the same molecular formula: C6H12O6 Isomers of each other Figure 2.15 © McGraw Hill 68  Carbohydrates 3 Disaccharides Sugars made of two covalently bonded monosaccharides Three important disaccharides: Sucrose (table sugar) Glucose + fructose Lactose (milk sugar) Glucose + galactose Maltose (sugar in grain products) Glucose + glucose Figure 2.16 © McGraw Hill 70  Carbohydrates 4 Oligosaccharides Short chains of three or more monosaccharides (at least 10) Polysaccharides Long chains of monosaccharides (at least 50) Three important polysaccharides: Glycogen Energy storage in cells of liver, muscle, brain, uterus, vagina Starch Energy storage in plants that is digestible by humans Cellulose Structural molecule in plants that is important for human dietary fiber (but indigestible to us) © McGraw Hill 72  Glycogen Figure 2.17 © McGraw Hill 73  Carbohydrates 5 Carbohydrates are a quickly mobilized source of energy All digested carbohydrates converted to glucose Oxidized to make ATP Carbohydrates are often conjugated with lipids or proteins Lipid and protein molecules at the external surface of the cell membrane often have chains of sugars attached to them Glycolipids Glycoproteins Glycoproteins are also a major component of mucus Proteoglycans are more carbohydrate than protein Gels that hold cells and tissues together; fill umbilical cord and eye Joint lubrication; responsible for the rubbery texture of cartilage © McGraw Hill 74  Lipids 1 Lipids are hydrophobic organic molecules with a high ratio of hydrogen to oxygen More calories per gram than carbohydrates Five primary types of lipids in the human body: Fatty acids Triglycerides Phospholipids Eicosanoids Steroids © McGraw Hill 75  Lipids 2 Fatty acids Chains of 4–24 carbon atoms with carboxyl group on one end and methyl group on the other Essential fatty acids must be obtained from food Fatty acids are classified as saturated or unsaturated Saturated fatty acids Carbon atoms linked by single covalent bonds Molecule contains as much hydrogen as possible (“saturated” with hydrogen) Unsaturated fatty acids Contain some double bonds between carbons Molecule has potential to add hydrogen Polyunsaturated fatty acids have multiple double bonds between carbons © McGraw Hill 76  Lipids 3 Triglycerides (Neutral Fats) Three fatty acids linked to glycerol Formed by dehydration synthesis; broken down by hydrolysis Primary function is energy storage Also help with insulation and shock absorption (adipose tissue) Dietary oils and fats are triglycerides “Oils” are usually liquid at room or body temperature Example: plant-derived polyunsaturated triglycerides such as corn and olive oils “Fats” are usually solid at room or body temperature Example: animal-derived saturated triglycerides (e.g., animal fat) The difference between “oil” and “fat” is somewhat arbitrary Example: coconut oil is solid at room temperature © McGraw Hill 77  Triglyceride (Fat) Synthesis 1 Figure 2.18a © McGraw Hill 78  Trans Fats and Cardiovascular Health Trans-fatty acids Two covalent single C – C bonds angle in opposites (trans, “across from each other”) on each side of the C = C double bond Resist enzymatic breakdown in the human body, remain in circulation longer, deposits in the arteries; thus, raises the risk of heart disease Cis-fatty acids Two covalent single C – C bonds angle in the same direction adjacent to the C = C Figure 2.19 double bond © McGraw Hill 80  Lipids 4 Phospholipids Similar to neutral fats except one fatty acid is replaced by a phosphate group Structural foundation of cell membrane Amphipathic Fatty acid “tails” are hydrophobic Phosphate “head” is hydrophilic © McGraw Hill 82  Lipids 6 Steroid Lipid with 17 carbon atoms in four rings Cholesterol The “parent” steroid from which other steroids are synthesized Important for nervous system function and structural integrity of all cell membranes 15% of our cholesterol comes from diet 85% is internally synthesized (mostly in liver) Other steroids include cortisol, progesterone, estrogens, testosterone, and bile acids Figure 2.22 © McGraw Hill 85  “Good” and “Bad” Cholesterol There is only one kind of cholesterol “Good” and “bad” cholesterol refer to droplets of lipoprotein in the blood that are complexes of cholesterol, fat, phospholipid, and protein HDL (high-density lipoprotein) = “good cholesterol” Lower ratio of lipid to protein May help to prevent cardiovascular disease LDL (low-density lipoprotein) = “bad cholesterol” High ratio of lipid to protein Contributes to cardiovascular disease © McGraw Hill 87  Proteins 1 Protein Polymer of amino acids Amino acid Central carbon with three attachments Amino group (-NH2) Carboxyl group (–COOH) Radical group (R group) 20 amino acids used to make the proteins are identical except for the radical (R) group Properties of each amino acid determined by the R group © McGraw Hill 88  Amino Acids Figure 2.23a © McGraw Hill 89  Proteins 2 Peptide Composed of two or more amino acids joined by peptide bonds Peptide bond Joins the amino group of one amino acid to the carboxyl group of the next Formed by dehydration synthesis Peptides are named for the number of amino acids they contain Dipeptides (2 amino acids) Tripeptides (3 amino acids) Oligopeptides (between 3 and 15 amino acids) Polypeptides (between 15 and 50 amino acids) Proteins (more than 50 amino acids) © McGraw Hill 90  Peptide Bond Formation Dehydration synthesis creates a peptide bond that joins the amino acid of one group to the carboxyl group of the next. Figure 2.23b © McGraw Hill 91  Protein Structure 1 Conformation Unique, three-dimensional shape of protein crucial to function Proteins can reversibly change conformation to affect function Important examples seen in muscle contraction, enzyme catalysis, membrane channel opening, and so on Denaturation Extreme conformational change that destroys function Extreme heat or pH may cause permanent (irreversible) denaturation Example: cooked egg white becomes opaque and stiff © McGraw Hill 92  Protein Structure 2 Primary structure Sequence of amino acids within protein molecule Primary structure is encoded by genes Secondary structure Coiled or folded shape held together by hydrogen bonds Hydrogen bonds between slightly negative C = O and slightly positive N – H groups Most common secondary structures are: Alpha helix (spring-like shape) Beta-pleated sheet (folded, ribbon-like shape) © McGraw Hill 93  Protein Structure 3 Tertiary structure Further bending and folding of proteins into globular and fibrous shapes due to hydrophobic–hydrophilic interactions and van der Waals forces Globular proteins Compact tertiary structure for proteins within cell membrane and proteins that move freely in body fluids Fibrous proteins Slender filaments suited for roles in muscle contraction and strengthening of skin and hair © McGraw Hill 94  Protein Structure 4 Quaternary structure Associations of two or more polypeptide chains due to ionic bonds and hydrophobic–hydrophilic interactions Occurs only in some proteins Example: hemoglobin has four peptide subunits Figure 2.24 © McGraw Hill 95  Protein Functions 1 Structure Keratin Tough structural protein of hair, nails, skin surface Collagen Contained in deeper layers of skin, bones, cartilage, and teeth Communication Neurotransmitters, some hormones, and other signaling molecules are proteins Signaling molecules that exert their effects by reversibly binding to a receptor molecule are called ligands The receptors to which the signaling molecules bind are also proteins © McGraw Hill 98  Protein Functions 2 Membrane transport Channel proteins allow hydrophilic substances to diffuse across cell membranes Carrier proteins help solutes cross cell membranes via active or passive transport Catalysis The enzymes that catalyze physiological reactions are usually globular proteins Recognition and protection Glycoproteins are important for immune recognition Antibodies are proteins © McGraw Hill 99  Protein Functions 3 Movement Motor proteins are molecules with the ability to change shape repeatedly Cell adhesion Proteins bind cells together © McGraw Hill 100  Enzymes and Metabolism Enzymes Proteins that function as biological catalysts Lower activation energy (the energy needed to get a reaction started) Permit reactions to occur rapidly at body temperature Substrate Substance an enzyme acts upon Enzyme naming convention Named for substrate with -ase as the suffix Examples: amylase catalyzes the hydrolysis of amylose (starch); lactase catalyzes the hydrolysis of lactose (milk sugar) © McGraw Hill 101  Effect of an Enzyme on Activation Energy Figure 2.26 © McGraw Hill 102  Enzyme Structure and Action 1 Enzyme action Substrate binds to enzyme’s active site Molecules form enzyme–substrate complex Enzyme–substrate specificity (lock and key) Enzyme releases reaction products Enzyme unchanged and can repeat process Example: sucrose hydrolysis © McGraw Hill 103  The Three Steps of an Enzymatic Reaction Figure 2.27 © McGraw Hill 104  Enzyme Structure and Action 2 Reusability of enzymes Enzymes are not consumed by the reactions Astonishing speed One enzyme molecule can catalyze millions of reactions per minute Temperature, pH and other factors can change enzyme shape and function Can alter ability of enzyme to bind to substrate Enzymes vary in optimum pH Salivary amylase works best at pH 7.0 Pepsin in stomach works best at pH 2.0 Temperature optimum for human enzymes is usually near body temperature (37°C) © McGraw Hill 105  ATP, Other Nucleotides, and Nucleic Acids Nucleotides Organic compounds with three principal components: Nitrogenous base (single or double carbon–nitrogen ring) Sugar (monosaccharide) One or more phosphate groups Examples of nucleotides: ATP (Adenosine triphosphate) cAMP (Cyclic adenosine monophosphate) © McGraw Hill 110  ATP and cAMP Figure 2.29 © McGraw Hill 111  Adenosine Triphosphate 1 ATP is the body’s most important energy-transfer molecule Stores energy gained from exergonic reactions Releases it within seconds for physiological work Holds energy in covalent bonds Second and third phosphate groups have high energy bonds (~) Most energy transfers to and from ATP involve adding or removing the third phosphate group © McGraw Hill 112  Adenosine Triphosphate 2 Hydrolysis of ATP is catalyzed by adenosine triphosphatases (ATPases) Breaks the third high-energy phosphate bond Separates ATP into ADP + Pi + energy Phosphorylation Addition of free phosphate group to a molecule Carried out by enzymes called kinases © McGraw Hill 113  Source and Uses of ATP Figure 2.30 © McGraw Hill 114  Nucleic Acids Nucleic acids are polymers of nucleotides DNA (deoxyribonucleic acid) Contains millions of nucleotides Constitutes genes Instructions for synthesizing proteins RNA (ribonucleic acid) Three types: messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA) 70 to 10,000 nucleotides long Carries out genetic instruction for synthesizing proteins Assembles amino acids in right order to produce proteins © McGraw Hill 118