Chapter 2

Hole’s Essentials of HumanAnatomy & Physiology

David ShierJackie ButlerRicki Lewis

Created by Dr. Melissa Eisenhauer Head Athletic Trainer/Assistant Professor

Trevecca Nazarene UniversityAmended by John Crocker

CopyrightCopyright©©The McGrawThe McGraw--Hill Companies, Inc. Permission required for reproduction or disHill Companies, Inc. Permission required for reproduction or display.play.

Chapter 2

Chemical Basis of Life

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ΞΞ Introduction:Introduction:

A.A. ChemistryChemistry deals with the composition of deals with the composition of substances and how they change.substances and how they change.B.B. A knowledge of chemistry is necessary for A knowledge of chemistry is necessary for the understanding of physiology because of the understanding of physiology because of the importance of chemicals in body the importance of chemicals in body processes.processes.

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ΞΞ Structure of Matter:Structure of Matter:

A.A. Elements and Atoms:Elements and Atoms:1.1. MatterMatter is anything that has weight and takes up is anything that has weight and takes up

space.space.2.2. All matter is composed of atomsAll matter is composed of atoms3.3. ElementsElements are atoms of one specific type defined

by the number of protons in the nucleus4.4. Atoms of different elements vary in size, weight, Atoms of different elements vary in size, weight,

and interaction with other atoms.and interaction with other atoms.

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5. 90 elements occur naturally. 5. 90 elements occur naturally. 6. Living organisms require about 20 elements, 6. Living organisms require about 20 elements,

of which of which oxygen, carbon, hydrogen, oxygen, carbon, hydrogen, andandnitrogennitrogen are most abundant.are most abundant.

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B.B. Atomic Structure: Atomic Structure: 1. An atom consists of a 1. An atom consists of a nucleus nucleus containing containing protonsprotons and and neutronsneutrons, with , with electronselectrons in orbit around the nucleus in shells.in orbit around the nucleus in shells.2. Protons, with a positive charge, are 2. Protons, with a positive charge, are about equal in size to neutrons, which about equal in size to neutrons, which have no charge. have no charge.

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3. Electrons are much smaller and bear 3. Electrons are much smaller and bear a negative charge.a negative charge.4. An electrically neutral atom has 4. An electrically neutral atom has equal numbers of protons and electrons.equal numbers of protons and electrons.5. The number of protons denotes the5. The number of protons denotes the atomic atomic numbernumber of an element; the number of protons of an element; the number of protons plus the number of neutrons equals the plus the number of neutrons equals the atomic atomic weight.weight.

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C.C. Bonding of Atoms: Bonding of Atoms: 1. Atoms form bonds by gaining, losing, 1. Atoms form bonds by gaining, losing, or sharing electrons.or sharing electrons.2. Electrons are found in shells around 2. Electrons are found in shells around the nucleus.the nucleus.

a.a. The first energy shell holds a The first energy shell holds a maximum of maximum of twotwo electrons; the electrons; the other energy shells each hold a other energy shells each hold a maximum of maximum of eighteight electrons when electrons when on the outside. on the outside.

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3. Atoms with incompletely filled outer 3. Atoms with incompletely filled outer shells tend to be reactive to form shells tend to be reactive to form stable outer shells of 8.stable outer shells of 8.

4. When atoms gain or lose electrons, 4. When atoms gain or lose electrons, they become they become ionsions with a charge. Whether they with a charge. Whether they gain or lose will depend on how many electrons gain or lose will depend on how many electrons they have in the outer shell to start with.they have in the outer shell to start with.

5. Oppositely5. Oppositely--charged ions attract each charged ions attract each other and form an other and form an ionic bondionic bond..

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6. 6. Covalent bondsCovalent bonds are formed when atoms are formed when atoms share electrons to become stable with filled share electrons to become stable with filled outer shells.outer shells.

a. Two pairs of electrons shared between a. Two pairs of electrons shared between atoms form a atoms form a double covalent bonddouble covalent bond. .

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D.D. Molecules and Compounds:Molecules and Compounds:

1. A 1. A moleculemolecule is formed when two or is formed when two or more atoms combine.more atoms combine.2. If atoms of different elements 2. If atoms of different elements combine, the molecule can also be combine, the molecule can also be called a called a compoundcompound..

a.a. Compounds always have a Compounds always have a definite kind and number of definite kind and number of atoms.atoms.

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E.E. Formulas:Formulas:

1. 1. A A molecular formulamolecular formula represents the numbers represents the numbers and types of atoms in and types of atoms in a molecule. a molecule. Ex: Glucose = CEx: Glucose = C66HH1212OO66

2. 2. Various representations, called Various representations, called structural structural formulasformulas, can be used to illustrate molecules., can be used to illustrate molecules.Ex: Water = H HEx: Water = H H

OO

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F.F. Chemical Reactions: Chemical Reactions: 1. A 1. A chemical reactionchemical reaction occurs as bonds are occurs as bonds are formed or broken between atoms, ions, formed or broken between atoms, ions, or or molecules.molecules.

2. Those changed by the reaction are the 2. Those changed by the reaction are the reactants;reactants; those formed are the those formed are the productsproducts..

3. Two or more atoms or molecules can be 3. Two or more atoms or molecules can be joined during joined during synthesissynthesis..

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4. Larger molecules can be broken into 4. Larger molecules can be broken into smaller ones in smaller ones in decompositiondecomposition reactions.reactions.

5. 5. Exchange reactionsExchange reactions occur as parts of occur as parts of molecules trade places.molecules trade places.

6. 6. Reversible reactionsReversible reactions are symbolized by are symbolized by using two arrows.using two arrows.

7. 7. CatalystsCatalysts influence the speed of influence the speed of chemical reactions.chemical reactions.

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G.G. Acids and Bases: Acids and Bases: 1. Substances that release ions in water 1. Substances that release ions in water are called are called electrolyteselectrolytes..

2. Electrolytes that release hydrogen 2. Electrolytes that release hydrogen ions in water are called ions in water are called acidsacids..

3. Electrolytes that release ions that 3. Electrolytes that release ions that combine with hydrogen ions in water combine with hydrogen ions in water are called are called basesbases..

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4. The concentrations of H4. The concentrations of H++ and OHand OH-- in in the body is very important to the body is very important to physiology.physiology.

5. 5. pHpH represents the concentration of represents the concentration of hydrogen ions [Hhydrogen ions [H++] in solution.] in solution.

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6. A 6. A pH of 7pH of 7 indicates a indicates a neutral solutionneutral solution with with equal numbers of hydrogen ions and hydroxyl equal numbers of hydrogen ions and hydroxyl (OH(OH--) ions.) ions.

a. A pH of a. A pH of zero to less than 7zero to less than 7indicates the presence of more indicates the presence of more hydrogen ions, and thus the hydrogen ions, and thus the solution is more solution is more acidic;acidic; a pH a pH greater than 7 to 14greater than 7 to 14 indicates indicates more hydroxyl ions, or a more hydroxyl ions, or a basicbasicsolution.solution.b. Between each whole number of b. Between each whole number of the pH scale there is a tenfold the pH scale there is a tenfold difference in hydrogen iondifference in hydrogen ionconcentration.concentration.

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7. 7. BuffersBuffers are chemicals that combine with excess acids or are chemicals that combine with excess acids or bases to help minimize pH changes in body fluids.bases to help minimize pH changes in body fluids.

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ΞΞ Chemical Constituents of Cells:Chemical Constituents of Cells:

A. A. OrganicOrganic compounds contain both hydrogen and compounds contain both hydrogen and carbon. carbon. B. All other compounds are considered B. All other compounds are considered inorganicinorganic..

1. 1. WaterWatera. Water is the most abundant a. Water is the most abundant compound in living things and compound in living things and makes up twomakes up two--thirds of the thirds of the weight of adults.weight of adults.

b. The polar structure of water allows b. The polar structure of water allows it to form hydrogen bonds which it to form hydrogen bonds which makes it a powerful solvent and gives makes it a powerful solvent and gives it a high heat capacityit a high heat capacity

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c. Water is an important c. Water is an important solventsolvent so most so most metabolic reactions occur in water.metabolic reactions occur in water.d. Water is important in transporting d. Water is important in transporting materials in the body since it is a major materials in the body since it is a major component of blood.component of blood.

e. Water carries waste materials and e. Water carries waste materials and can absorb and transport heat.can absorb and transport heat.f. The polar structure of waterf. The polar structure of water

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2.2. Oxygen Oxygen a. Oxygen is needed to release energy a. Oxygen is needed to release energy from nutrients and is used to drive from nutrients and is used to drive the cell's metabolism.the cell's metabolism.

3.3. Carbon DioxideCarbon Dioxidea. Carbon dioxide is released as a waste a. Carbon dioxide is released as a waste product during energyproduct during energy--releasing releasing metabolic reactions. metabolic reactions.

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4.4. Inorganic SaltsInorganic Saltsa. Inorganic salts provide necessary ions a. Inorganic salts provide necessary ions including sodium, chloride, potassium, including sodium, chloride, potassium, calcium, magnesium, phosphate, calcium, magnesium, phosphate, carbonate, bicarbonate, and sulfate.carbonate, bicarbonate, and sulfate.b. These electrolytes play important b. These electrolytes play important roles in many of the body's metabolic roles in many of the body's metabolic processes. processes.

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C.C. Organic Substances:Organic Substances:1.1. CarbohydratesCarbohydrates

a. Carbohydrates provide energy for a. Carbohydrates provide energy for cellular activities and are composed of cellular activities and are composed of carbon, hydrogen, and oxygen.carbon, hydrogen, and oxygen.b. Carbohydrates are made from b. Carbohydrates are made from monosaccharidesmonosaccharides (simple sugars); (simple sugars); disaccharidesdisaccharides are two monosaccharides are two monosaccharides joined together; complex carbohydrates joined together; complex carbohydrates (polysaccharides(polysaccharides),), such as starch, are built such as starch, are built of many sugars.of many sugars.c. Humans synthesize the polysaccharide c. Humans synthesize the polysaccharide glycogenglycogen. .

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2.2. Lipids:Lipids:a.a. LipidsLipids are organic substances that are are organic substances that are insoluble in water and include insoluble in water and include fats, fats, phospholipids, phospholipids, andand steroids.steroids.b.b. FatsFats supply energy for cellular function, and supply energy for cellular function, and are built from glycerol and three fatty acids. Fats are built from glycerol and three fatty acids. Fats have a smaller proportion of oxygen atoms than have a smaller proportion of oxygen atoms than carbohydrates.carbohydrates.

i.i. Fatty acids with hydrogen at every Fatty acids with hydrogen at every position along the carbon chain are position along the carbon chain are saturated;saturated; those with one or more those with one or more double bonds are called double bonds are called unsaturated unsaturated fats.fats.

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c.c. PhospholipidsPhospholipids contain glycerol, two fatty contain glycerol, two fatty acids, and a phosphate group, and are acids, and a phosphate group, and are important in cell structures.important in cell structures.

d.d. SteroidsSteroids are complex ring structures, and are complex ring structures, and include cholesterol, which is used in cell include cholesterol, which is used in cell membranes and to synthesize the sex membranes and to synthesize the sex hormones. hormones.

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3.3. Proteins:Proteins:a. a. ProteinsProteins have a great variety of have a great variety of

functions in the bodyfunctions in the body----as structural as structural materials, as energy sources, as materials, as energy sources, as certain hormones, as receptors on certain hormones, as receptors on cell membranes, as cell membranes, as antibodiesantibodies,, and and as as enzymesenzymes to catalyze metabolic to catalyze metabolic reactions.reactions.

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b. Proteins contain C, O, H, and b. Proteins contain C, O, H, and nitrogennitrogen atoms; some also contain atoms; some also contain sulfur.sulfur.c. Building blocks of proteins are the c. Building blocks of proteins are the amino acidsamino acids, each of which has a , each of which has a carboxyl group, an amino group and carboxyl group, an amino group and a side chain called the R group.a side chain called the R group.

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d. Proteins have complex shapes held d. Proteins have complex shapes held together by hydrogen bonds.together by hydrogen bonds.

e. Protein shapes, which determine e. Protein shapes, which determine how proteins function, can be altered how proteins function, can be altered (denatured) by pH, temperature, radiation, or (denatured) by pH, temperature, radiation, or chemicals. chemicals.

Protein DenaturationFlash

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4.4. Nucleic AcidsNucleic Acids::a. a. Nucleic acidsNucleic acids form genes and take form genes and take

part in protein synthesis.part in protein synthesis.b. b. They contain carbon, hydrogen, They contain carbon, hydrogen,

oxygen, nitrogen, and phosphorus, oxygen, nitrogen, and phosphorus, which are bound into building which are bound into building blocks called blocks called nucleotidesnucleotides..

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c. Nucleic acids are of two major c. Nucleic acids are of two major types: types: DNADNA (with deoxyribose) and (with deoxyribose) and RNA (with ribose).RNA (with ribose).

d. RNA d. RNA ((ribonucleic acidribonucleic acid)) functions in functions in protein synthesis; DNA protein synthesis; DNA (deoxyribonucleic acid)(deoxyribonucleic acid) stores the stores the molecular code in genes.molecular code in genes.

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LaboratoryLaboratory

You will need to reference your book for this You will need to reference your book for this weeks lab to bring both your book and lab weeks lab to bring both your book and lab manualmanual

This one is primarily descriptive and vocabulary so This one is primarily descriptive and vocabulary so it should be quick and easyit should be quick and easy

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Some Latin to remember for the lab Some Latin to remember for the lab (and for later)(and for later)

Ante Ante –– in front of or beforein front of or beforePost Post –– behindbehindHyper Hyper –– high or abovehigh or aboveEpiEpi –– upon, attached to, over, outer, afterupon, attached to, over, outer, afterHypo Hypo –– low or belowlow or belowPeriPeri –– near, surroundingnear, surroundingEndo Endo –– innerinnerExoExo –– outerouterSuper Super –– Above or dorsalAbove or dorsal