An Introduction to Physiology-physiology: the study of the functions of living things 1. skeletal

2. articular3. muscular4. digestive5. respiratory6. urinary7. reproductive8. circulatory9. nervous10. integumentary11. endocrine

-the human body is comprised of 11 major organ systems:

- in studying these systems we can use two approaches:1. teleological

-emphasizes the purpose of a body process -explains a function in terms of meeting a bodily need-emphasizes the WHYe.g. “why do I shiver?” – to warm up because shivering generates heat

2. mechanistic-emphasizes the underlying mechanism by whichthis process occurs-view the body as a machine whose actions can be explainedin terms of cause and effect-emphasize the HOWe.g. “why do I shiver?” – detection of body temperature by sensoryreceptors leads to activation of the somatic division of the nervoussystem and trigger the involuntary contraction of skeletal muscles

-physiology is closely related to anatomy – because structure and function are closely related-physiological mechanisms are made possible because of the structure and designof a body part-some relationships are obvious – e.g. structure of the elbow as a hinge joint-others are more subtle – e.g. interface between the air and the blood in the lungs

-air sac structure + capillary bed - 300 million air sacs + associated capillaries providesa total surface area for gas exchange = tennis court

Life: Levels of Organization•Atoms •Molecules•Macromolecules•Organelles•Cells•Tissues•Organs•Organ systems•Organism

THE ELEMENTS OF LIFE• ABOUT 20–25% OF THE 92 NATURAL ELEMENTS ON EARTH ARE ESSENTIAL TO

LIFE = ESSENTIAL ELEMENTS• NEEDED TO LIVE A HEALTHY LIFE AND REPRODUCE

• OF THE TOTAL AMOUNT OF NATURAL ELEMENTS ON EARTH - CARBON, HYDROGEN, OXYGEN, AND NITROGEN MAKE UP 96%

• MOST OF THE REMAINING 4% CONSISTS OF CALCIUM, PHOSPHORUS, POTASSIUM, AND SULFUR

• TRACE ELEMENTS ARE THOSE REQUIRED BY AN ORGANISM IN MINUTE QUANTITIES

• some natural elements can be toxic, for example, chromium

• some species can become adapted to environments containing toxic elements

– e.g. some plant communities are adapted to serpentine (jade-like rock containing chromium, nickel and cobalt)

Organizational Levels

1. chemical or molecular: 4 major elements within the human body-99% of the total number of atoms within the body-C, N, O and H

-molecular composition - 67% of our bodies is water

Atom = smallest unit of an element that still retains the chemical &physical properties of that element

i.e. really, really, really tiny thing!

-composed of: protons = one positive charge, 1 atomic mass unit (1.673x10-24g)electrons = one negative charge, no mass (9.109x10-28g)neutrons = no charge, 1 atomic mass unit

each atom is comprised of a nucleus of protons and neutrons + orbiting electrons

-elements are grouped on a Periodic Table of Elements-the elements are grouped according to physical and chemical characteristics-on the chart each element is associated with a letter, an atomic number & an atomic mass

PERIODIC TABLE OF ELEMENTS

IA IIA VIIAVIIIIIIA IVA VA VIA

http://oxford-labs.com/x-ray-fluorescence/the-periodic-table/

73 Li

atomicmass (weight)

atomicsymbol

atomicnumber

e.g. # protons (e-) = 3 # pr+3 + #No 4 = 7

Atomic mass = number of protons + neutronsAtomic number = number of protons when the element is electrically neutral** when neutral, the number of protons and electrons are equal

e.g. # protons (e-) = 19 # pr+19 + #No 20 = 39

3919K

Isotope:•all atoms in an element have the same number of protons but may differ in number of neutrons

• the number of protons defines what the element is• e.g. 6 protons = carbon and only carbon

•isotopes are two atoms of an element that differ in number of neutrons•in nature an element is a mixture of its isotopes

12C 13C 14C

pr+: 6 6 6e-: 6 6 6No: 6 7 8** radioactive

• the protons and neutrons in the nucleus are held together by a kind of nuclear “glue”

• when the number of neutrons increase – the nucleus becomes unstable

• the breakup of the nucleus releases particles with energy in the form of radioactivity• also known as radioactive decay• three different kind of particles released – each with different

energy levels• alpha (helium atom), beta and gamma

• the decay can eventually change the # protons – transform one atom into another

Radioactivity

Radioactive isotope uses:

-radioactive isotopes have a high neutron to proton ratio-the nuclear “glue” within the nucleus is not strong enough to hold the nucleus together = radioactivity1. carbon dating - 14C2. radioactive imaging - e.g. PET scanning

-use of FDG – radioactive glucose tracer-18F radioactive isotope (2-fluoro-deoxy-glucose)

3. cancer treatment - 60Co, 131I

Cancerousthroattissue

Chemical bonds

-forces holding atoms together = chemical bonds-different kinds of chemical bonds – but all involve the electrons of atoms

Two types of bonds:

1. Ionic

2. Covalent

The Energy levels of Electrons

•Energy is the capacity to cause change•Potential energy is the energy that matter has because of its location or structure•the electrons of an atom differ in their amounts of potential energy

• because of their location around the nucleus•an electron’s state of potential energy (i.e its position around a nucleus) is called its energy level or electron shell

Electron Configurations

•“bed check” for electrons•description of how the electrons are organized around the nucleus•Bohr Model: Nils Bohr proposed that electrons orbit around the atom’s nucleus at specific potential energy levels or shells

• these shells have specific energy levels – closer to the nucleus the less energy they need to “orbit”

• this model only works for smaller atoms (1st 4 rows of the periodic table)

• larger atoms are described by quantum mechanics• electrons have potential energy, spin,

momentum/shape and magnetic properties

Electron Configurations

•each electron shell is comprised of subshells called orbitals•each orbital is a potential space where you can find a pair of electrons 90% of the time•1st shell – closest to the nucleus; comprised of an ‘s’ orbital with 2 electrons•2nd shell - comprised of an ‘s’ orbital (2 electrons) and 3 ‘p’ orbitals holding a total of 6 electrons = 8 electrons total•3rd shell - comprised of an ‘s’ orbital (2 electrons), 3 ‘p’ orbitals (6 electrons) and 5 ‘d’ orbitals that can hold 10 electrons max = 18 electrons total•4th shell - comprised of an ‘s’ orbital (2 electrons), 3 ‘p’ orbitals (6 electrons) and 5 ‘d’ orbitals (10 electrons) = 18 electrons total

Electron Configurations

• each orbital holds a pair of electrons

• s orbital = 2 electrons• 3 p orbitals = 6 electrons• 5 d orbitals = 10 electrons

• we don’t care about the d orbital electrons because they don’t participate in bonding reactions

Neon, with two filledShells (10 electrons)

First shell

Second shell

First shell Second shell

1s orbital 2s orbital Three 2p orbitals

(a) Electron distribution diagram

(b) Separate electron orbitals

(c) Superimposed electron orbitals

1s, 2s, and2p orbitals

x y

z

• the ability of an atom to form a chemical bond is determined by the distribution of electrons in electron shells• the reactivity of certain atoms results from the presence of unpaired

electrons in one or more orbitals

• an atom will always try to complete its outermost shell = valence shell• basis for bonding reactions• the number of electrons in the outer most electron shell available for

bonding reactions = valence electrons• chemists really only consider the electrons in the s and p orbitals as

valence electrons

• once an atom completes fills up its valence orbitals – it is chemically inert• unable to participate in bonding reactions

Valence = 1 Valence = 4 Valence = 3 Valence = 2

Valence = 1 Valence = 7 Valence = 1 Valence = 7

First shell

Second shell

Third shell

Hydrogen

1H

Lithium

3Li

Sodium

11Na

Beryllium

4Be

Magnesium

12Mg

Boron

5B

Aluminum

13Al

Carbon

6C

Silicon

14Si

Nitrogen

7N

Phosphorus

15P

Oxygen

8O

Sulfur

16S

Fluorine

9F

Chlorine

17Cl

Neon

10Ne

Argon

18Ar

Helium

2HeElectrondistributiondiagram

• the periodic table of the elements tells you the electron distribution for each element• by its row and column position• 1st row – valence electrons in the first electron shell• 2nd row – valence electrons in the second electron shell• 1st column – 1 valence electron• 3rd column – 3 valence electrons

I

II III IV V VI

VIII

VII

Molecule:

•particle formed by the union of more than one atome.g. same kind of atom - O2

e.g. different types of atoms - H20

• Molecules are held together by either covalent or ionic bonds-these bonds form through interactions between the valence electrons

• attraction between 2 oppositely charged atoms (ions)e.g. Na+ and Cl- NaCle.g. Ca2+ and Cl- CaCl2

• ion = charged atom• positively charged ions = cations• negatively charged ions = anions• ions form as one atom transfers electrons to another

atom• ions may also be composed of more then one atom =

polyatomic• these are treated as the same as monoatomic ions

e.g. sulfate SO43-, nitrite NO2

-, hydroxide OH-

1. Ionic bond

Ionic Reaction

most of your group IA and group IIAmetals will form ionic bonds with thegroup VIIA halogens

• if it isn’t favorable for an atom to gain or lose an electron• it will have to share it with another

covalent bond = bond in which atoms share electronse.g O2, , N3

e.g H20• covalent bonds usually form when one atom has to lose or gain three or more electronse.g. carbon would have to gain 4 electrons to complete its outer valence shelle.g. nitrogen would have to gain 3 electrons-also form between two identical atoms – e.g. nitrogen, oxygen gas

2. Covalent Bond

• COVALENT BONDING BY SOME COMMON BIOLOGICAL ELEMENTS

• HYDROGEN = VALENCE 1; 1 ELECTRON NEEDED

• OXYGEN = VALENCE 2; 2 ELECTRONS NEEDED

• SULFUR = VALENCE 2; 2 ELECTRONS NEEDED

• NITROGEN = VALENCE 3; 3 ELECTRONS NEEDED

• CARBON = VALENCE 4; 4 ELECTRONS NEEDED

• PHOSPHORUS = VALENCE 3; 3 ELECTRONS NEEDED

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COVALENT BONDS FOR THE PHYSIOLOGIST

• so we can now modify the definition of a molecule further• a molecule consists of two or more atoms held together

by covalent bonds• a single covalent bond – or single bond – is the sharing of

ONE pair of valence electrons• denoted with the structural formula H-H

• a double covalent bond – or double bond – is the sharing of TWO pairs of valence electrons• denoted as O=O or C=C

• the sharing of electrons is often NOT EQUAL• equal sharing of electrons = non-polar covalent bond

• e.g. carbon-containing compounds (CH4), gases (O2, N2)• unequal sharing of electrons = polar covalent bond

• e.g. oxygen-containing compounds (H2O)• creates a slight +ve and –ve charge within the molecules

Polar and Non-Polar Bonds

Chemical reactions:

3 types:

1. Synthesis - A + B AB (Anabolism reactions)

2. Decomposition - AB A + B (Catabolism reactions)

3. Exchange - AB + CD AD + BC

-reactions must be balanced-Law of conservation of Mass or “chemical book keeping”-i.e. the number of atoms of each element is the same before and after a chemical reaction

Chemical reactions

• are made up of Reactants and Products• 3 types:

1. Synthesis - A + B AB (Anabolism reactions)2. Decomposition - AB A + B (Catabolism reactions)3. Exchange - AB + CD AD + BC

-reactions must be balanced-Law of conservation of Mass or “chemical book keeping”-i.e. the number of atoms of each element is the same before and after a chemical reaction

• these three types of reactions go on constantly in the human body = Metabolism

• each reactions involves a change in energy• if the reaction requires energy =

Endergonic• if the reactions liberates energy =

Exergonic • if a reaction liberates energy in

the form of heat it is also called Exothermic

Chemical reactions(a) Exergonic reaction: energy released, spontaneous

(b) Endergonic reaction: energy required, nonspontaneous

Reactants

EnergyProducts

Progress of the reaction

Amount of energy

released(G 0)

ReactantsEnergy

Products

Amount of energy

required(G 0)

Progress of the reaction

Fre

e en

erg

yF

ree

ener

gy

• atoms, molecules and ions are continuously moving and colliding with one another = Kinetic energy

• if this kinetic energy is big enough (i.e. collision is large enough) – can form or break up a bond

• this collision energy = Activation energy

• critical to the progression of all chemical reactions in our body

• the more often a collision occurs – the greater the chance a bond will form or break

Activation Energy

ACTIVATION ENERGY

• Activation energy = initial energy investment required to start a reaction

• in a chemical reaction - the reactants must absorb enough energy to cause their chemical bonds to become unstable and form new ones

• this energy is called the free energy of activation or Activation Energy

• get this energy from the environment• as activation energy is put into a reaction – the

reactants’ bonds weaken new products form as these ‘transition state’ reactants collide with one another

• activation energy is often supplied in the form of thermal energy = HEAT

Transition state

Reactants

Products

Progress of the reaction

Fre

e e

ner

gy

EA

G O

A B

C D

A B

C D

A B

C D

ACTIVATION ENERGY

• as the new bonds of the products form – energy may be released into the environment (i.e. the cell)

• if more energy is released than absorbed by the products – Exergonic/Exothermic

• two influences on activation energy and reaction rates

• 1. temperature – heating a reaction can increase the kinetic energy of the reactants and make achieving activation energy easier

• 2. concentration – increasing concentration increases the chance that a collision will occur among reactants

Transition state

Reactants

Products

Progress of the reaction

Fre

e e

ner

gy

EA

G O

A B

C D

A B

C D

A B

C D

ACTIVATION ENERGY & CATALYSTS

• so a chemical reaction gets its activation energy from the environment

• this won’t work for the cells of the human body• takes too long

• we need to speed up these reactions = Catalyst• Catalyst = something that lowers a reaction’s

Activation energy and speeds up the formation of products

• in cells – the catalyst is called an Enzyme• Enzyme = protein that speeds up (catalyzes) a

reaction without being consuming in the reaction

• enzymes speed up reactions that would occur naturally

Molecules of Life:

• the chemicals used in metabolic reactions or those that are produced by them can be classified into 2 groups:

1. Inorganic2. Organic

INORGANIC COMPOUNDS

water oxygen, carbon dioxide inorganic salts

O

H H

-

++

Water:• 60-70% of body weight• covalent bond• POLAR molecule (uneven sharing of electrons)

•polar compounds are attracted to other•the bond between one oxygen andthe hydrogens of adjacent watermolecules = Hydrogen Bond**HB = occurs between a covalentlybonded hydrogen and negativelycharged atom a distance away

WATER

• major component of blood plasma, interstitial fluids, CSF etc…• hydrogen bonding allows the even distribution of dissolved substances

throughout our system – so water is an excellent transportmedium

•role in: transporting chemicals, transporting waste products• polar molecule - asymmetrical distribution of charge• liquid at room temperature – we can drink it

•universal solvent for polar compounds – facilitates most chemical reactions in the body-the temperature of water rises and falls slowly – prevents sudden and drastic changes of temperature in our bodies-water requires high heat to evaporate – it cools our bodies-frozen water is less dense than liquid water – ice floats -water freezes from the top down – allows aquatic organisms to survive winters

O

H H

-

++

Water:

-excellent solvent for dissolution of polar and ionic substancese.g. H20 + NaCl

-in a solution – a solvent dissolves another substance calleda solute-water is a versatile solvent because of its polar covalent bonds and its bent shape which allows it to interact with its neighbours very well

•ions and molecules that react with water =

•ions and molecules that don’t react =

-water + salt: the electronegative O ofwater attracts the +ve sodium in salt, theelectropositive H attracts the –ve chlorine-the salt becomes surrounded by watermolecules and the crystal lattice of saltis broken up

SOLUTIONS, COLLOIDS AND SUSPENSIONS

• MIXTURE = TWO OR MORE TYPES OF ELEMENTS OR MOLECULES PHYSICALLY BLENDED TOGETHER IN A SOLVENT WITHOUT THE FORMATION OF PHYSICAL BONDS BETWEEN THEM

• 1. SOLUTION = HOMOGENOUS (SAME) MIXTURE OF SUBSTANCES DISSOLVED IN A SOLVENT• E.G. SUGAR + WATER• THE MIXTURE IS THE SAME NO MATTER WHERE YOU SAMPLE IT• SUBSTANCES ARE VERY SMALL AND ARE NOT ACTED UPON BY GRAVITY – REMAIN SUSPENDED IN THE SOLUTION

• 2. COLLOID = SOLUTION OF LARGER COMPONENTS CALLED DISPERSED-PHASE PARTICLES• THEIR PARTICLES ARE LARGER THAN THAT OF SOLUTIONS• HAVE THE POTENTIAL TO SETTLE OUT DUE TO GRAVITY• BUT: THESE PARTICLES ALL CARRY THE SAME CHARGE (REPEL EACH OTHER) – SO THEY REMAIN SUSPENDED IN THE

SOLVENT• E.G. PLASMA PROTEINS WITHIN THE BLOOD

• 3. SUSPENSION = SOLUTION OF EVEN LARGER COMPONENTS THAT ARE SOLID AND CAN SETTLE OUT

• LARGER PARTICLES THAN THAT OF COLLOID• IF LEFT UNDISTURBED THESE PARTICLES WILL SETTLE OUT TO FORM A SOLID

• E.G. RED BLOOD CELLS WITHIN BLOOD

ELECTROLYTES

• substances that release ions when they react with water-these ions will conduct electricity = Electrolytes-created through the decomposition of ionic substances

e.g. salt-although polar compounds can also liberate electrolytes

Inorganic salts: • abundant in body fluids• source of ions eg. Na+, Ca2+, K+, Mg2+

ions play a role in: maintaining water concentration maintaining pH

bone development muscle function

nerve function ions must be maintained in a certain concentration

to maintain homeostasis

Inorganic Acids & Bases•3 types: 1. release H+ Acids

e.g. HCl H+ + Cl-

2. release ions to combine with H+ Basese.g. NaOH Na+ + OH-

3. acids + bases Salts e.g. HCl + NaOH H20 + NaCl

pH Scale• measures concentration of H+ ions in a solution

e.g. pH 6 = 1 x 10-6

pH 7 = 1 x 10-7

pH 8 = 1 x 10-8

Buffers:

• chemical or compound that keeps the pH of a solution withina normal range• resists pH change by taking up excess H+ or OH- ions

e.g. blood = pH 7.4“Bicarbonate buffering system”- our blood contains a small amount of

carbonic acid-carbonic acid dissociates into H+ and bicarbonate-bicarbonate takes up excess H+ ions

H2CO3 H+ HCO3-

excess OH- excess H+

+

H20

carbonic acid

ORGANIC MOLECULES

THE FORMATION OF BONDS WITH CARBON

• IN MOLECULES WITH MULTIPLE CARBONS, EACH CARBON BONDED TO FOUR OTHER ATOMS HAS A TETRAHEDRAL SHAPE

• HOWEVER, WHEN TWO CARBON ATOMS ARE JOINED BY A DOUBLE BOND, THE ATOMS JOINED TO THE CARBONS ARE IN THE SAME PLANE AS THE CARBONS

Name andComment

MolecularFormula

(a) Methane

(b) Ethane

CH4

Ball-and-Stick Model

Space-FillingModel

(c) Ethene (ethylene)

C2H6

C2H4

StructuralFormula

• THE VALENCES OF CARBON AND ITS MOST FREQUENT PARTNERS (HYDROGEN, OXYGEN, AND NITROGEN) ARE THE “BUILDING CODE” THAT GOVERNS THE ARCHITECTURE OF LIVING MOLECULES

Hydrogen(valence 1)

Oxygen(valence 2)

Nitrogen(valence 3)

Carbon(valence 4)

Urea

ORGANIC COMPOUNDS

• THE SKELETON OF CARBON AND HYDROGEN ARE FREQUENTLY COMBINED WITH OTHER ATOMS AND MOLECULES = FUNCTIONAL GROUPS

- functional groups confer a specific property or function to the organic compounde.g. hydrophilic characteristic of the carboxyl group

CH C

H

H

C

H

HC

H

H

O

OH

carboxylgroup = hydrophilic

CH C

H

H

C

H

HC

H

H

O

O-

de-protonated carboxylgroup

EstradiolTestosterone

- hydrophilic functional groups important in physiology:- hydroxyl- carboxyl- sulfate- phosphate

Organic substances:1. carbohydrates2. lipids3. proteins4. nucleic acids

1. Carbohydrates:• provide energy to cells

• can be stored as reserve energy supply (humans = glycogen)• supply “building materials” to build certain cell structures

• e.g. cell wall of plants• water soluble = hydrophilic• characterized H - C - OH (ratio C:H 1:2)

e.g. glucose C6H12O6

sucrose C12H22O12

• classified by size: simple sugars – saccharides complex – polysaccharides

monosaccharidesdisaccharides

A. Simple carbohydrates

monosaccharides found in humans: glucose galactose fructose

• monosaccharides = known as simple sugars• single saccharide subunit in which the # of carbon atoms is low - from 3

to 7• e.g. 5 carbon sugar = pentose• e.g. 6 carbon sugar = hexose

- formula: C:2H:O

Monosaccharides:

- in aqueous solutions – the monosaccharides are not linear-they form rings

-three ways to represent the ring structure of a monosaccharide

1. Molecular ring form

3. Simplest form

2. Abbreviated ring structure

GLUCOSE, FRUCTOSE AND GALACTOSE

beta-glucose(OH above the ring plane)

alpha-glucose(OH below the ring plane)

beta-galactose(isomer of glucose at the 4 carbon)

fructose

** molecules with the same chemical composition but with different structuresare known as Isomers

A. Simple carbohydrates

• disaccharide = two 6-carbon monosaccharides joined through a glycosidic linkage

-forms by a dehydration synthesis reaction-broken up by a hydrolysis reaction

e.g. glucose + glucose = maltose

e.g. glucose + fructose = sucrosee.g. glucose + galactose = lactose

B. Complex carbohydrates:

• built of simple carbohydrates to form macromolecules• multiple, repeating monomers or “building blocks” polymer• some serve as storage materials – hydrolyzed into individual monosaccharides • others serve as structural or building materials – e.g. cellulose

Storage Polysaccharides

•Starch & Glycogen = storage polysaccharides• stored by plants and animals as a future sugar supply

•glycogen = storage form of glucose found in animals

• stored in the liver and muscle• very highly branched• hydrolyzed into glucose

•starch = storage form of glucose found in plants • simplest ones (e.g. amylose) are helical

and unbranched in conformation• some are more complex – with branch

points (e.g. amylopectin)• hydrolyzed into glucose by enzymes –

found in both plants and animals

(a) Starch: a plant polysaccharide

(b) Glycogen: an animal polysaccharide

ChloroplastStarch granules

MitochondriaGlycogen granules

Amylopectin

Amylose

Glycogen

1 m

0.5 m

Cellulose

• polysaccharide found in cell walls in plants• comprised of cellulose molecules grouped parallel to one another to

form a microfibril• linkage between glucose monomers differs from starch or glycogen

• not helical or branched• indigestible by humans

• known as insoluble fiber• “scrapes” the lining of the GI tract and causes the production of mucus

– smoother transport for waste•digestible by bacteria – possess the enzyme Cellulase

Cell wallMicrofibril

Cellulosemicrofibrils in aplant cell wall

Cellulosemolecules

Glucosemonomer

10 m0.5 m

Structural Polysaccharides

COMPLEX CARBOHYDRATES: HIGH FRUCTOSE CORN SYRUP (HFCS)

• FIRST DESCRIBED IN 1957 BY RICHARD MARSHALL AND EARL KOOI

• REQUIRED THE USE OF ARSENIC TO MAKE IN LARGE QUANTITIES

• PERFECTED FOR COMMERCIAL USE IN 1961 – YAMANAKA

• HFCS = ANY CORN SYRUP THAT HAS UNDERGONE ENZYMATIC PROCESSING (BY MICROBES) TO CONVERT SOME OF ITS GLUCOSE MONOMERS INTO FRUCTOSE

• HFCS55 – 55% FRUCTOSE AND 42% GLUCOSE (SIMILAR TO HONEY)

• HFCS42 – 42% FRUCTOSE AND 53% GLUCOSE

• HFCS90 – 90% FRUCTOSE – USED TO CREATE OTHER FORMS OF HFCS

• CHEAPER THAN SUCROSE DUE TO IMPORT TARIFFS ON SUGAR CANE AND/OR SUCROSE• ADDED TO COKE IN 1984 IN THE US

• USED BECAUSE FRUCTOSE IS SWEETER THAN GLUCOSE• “SWEETNESS SCALE” – FRUCTOSE = 173

• HFCS = 120; SUCROSE = 100; GLUCOSE = 74; CORN SYRUP = 40

• NO DIFFERENCE BETWEEN HFCS AND SUCROSE IN TERMS OF SATISFACTION AND HEALTH EFFECTS??• TYPICAL AMERICAN WEIGHS 25 LBS MORE THAN 25 YRS AGO

• HFCS ENTERED INTO THE AMERICAN DIET IN 1975

SUGAR: SWEET TREAT OR TOXIN?

• YOUTUBE: SUGAR: THE BITTER TRUTH (UC TV)

• TODAY THE AVERAGE TEENAGE BOY EATS AND DRINKS 275 MORE CORIES PER DAY• AVERAGE ADULT – 187 MORE CALORIES (KCAL)

• AVERAGE TEENAGE GIRL – 335 MORE CALORIES

• ONE POUND = 3,555 CALORIES

• EXTRA WEIGHT IS NOT FROM FAT • 228/275 CALORIES IS FROM CARBOHYDRATES

• TODAY THE CALORIES WE GET FROM FAT ARE DECREASING – YET OBESITY IS INCREASING

• 41% INCREASE IN SOFT DRINKS; 35% INCREASE IN FRUIT DRINKS/”ADES” • 1 CAN SODA = 150 KCAL X 365 DAYS IN A YEAR = 15.61 LBS!!!!

• AVERAGE AMERICAN INGESTS 141 LBS OF SUGAR PER YEAR (63 LBS OF HFCS)

• COKE• 1915 – 6.5 OZ BOTTLE

• 1955 – 10 OZ

• 1960 – 12 OZ CAN WAS INTRODUCED

• 1992 – 20 OZ PLASTIC BOTTLE (2.5 SERVINGS)

• 1988 – 44 OZ “BIG GULP” (57 LBS PER YEAR)

• STUDIES NOW SHOW AN INCREASE IN BMI AND TYPE II DIABETES CORRESPONDING TO AN INCREASE IN SOFT DRINK CONSUMPTION

“Coke conspiracy”-Coke recipe contains caffeine to make you pee and contains salt-end result = THIRST-sugar hides the salt

LIPIDS

• MANY TYPES• 1. TRIGLYCERIDES = FATS AND OILS• 2. PHOSPHOLIPIDS• 3. STEROIDS

• CHOLESTEROL – ANIMAL CELL MEMBRANES, BASIS FOR STEROID HORMONES

• BILE SALTS - DIGESTION• VITAMIN D – CALCIUM REGULATION• ADRENOCORTICOSTEROID HORMONES• SEX HORMONES

• 4. EICANOSOIDS• PROSTAGLANDINS• LEUKOTRIENES

• 5. OTHERS• FATTY ACIDS• CAROTENES – SYNTHESIS OF VITAMIN A• VITAMIN E – WOUND HEALING• VITAMIN K – BLOOD CLOTTING• LIPOPROTEINS – HDL AND LDL• WAXES AND PIGMENTS

longest lasting, most plentiful energy supply of the human body• composed of C, H and O• “building blocks” = 3 fatty acid chains (hydrocarbons usually

from 16 to 24 carbons) PLUS 1 glycerol molecule

fatty acid

fatty acid

fatty acid

glycerol portion fatty acid portion

A. Fats

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• FORMED THROUGH DEHYDRATION SYNTHESIS REACTIONS TO FORM AN ESTER LINKAGE

• THE THREE FATTY ACIDS JOINED TO GLYCEROL CREATES A TRIACYLGLYCEROL, OR TRIGLYCERIDE

(a) One of three dehydration reactions in the synthesis of a fat

Fatty acid(in this case, palmitic acid)

Glycerol

(b) Fat molecule (triacylglycerol)

Ester linkage

• fatty acids -differ in chain length with each fat -also differ in the location and number of double bonds

within the hydrocarbon chains

1. single C bonds - saturated

2. double C bonds - unsaturated

monounsaturated:1 double bond

polyunsaturated:2 or more double bonds

• Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds

• Unsaturated fatty acids have one or more double bonds

(a) Saturated fat (b) Unsaturated fat

Structuralformula of asaturated fatmolecule

Space-fillingmodel of stearicacid, a saturatedfatty acid

Structuralformula of anunsaturated fatmoleculeSpace-filling modelof oleic acid, anunsaturated fattyacid Cis double bond

causes bending.

• at room temperature – the molecules of a saturated fat are packed closely together• the fatty acid tails are more flexible• forms a solid

• the molecules of an unsaturated fat cannot pack closely together enough to solidify• the C=C bonds produce a “kink” in the fatty acid chain - making it difficult to pack them

together• if the fat contains one fatty acid that is unsaturated – then the fat is considered

unsaturated

• in hydrogenated oils – the unsaturated fats have been chemically converted to saturated by adding hydrogens• prevents their separation into an oil form – keeps them solid

• polyunsaturated fats are considered an important part of our diet– lower LDL, increase calcium utilization, reduce inflammation, promote wound healing

-a gram of fat stores twice as much energy vs. a gram of a polysaccharide like starch-some fatty acids cannot be made by the body and must be taken in through food = essential fatty acids

e.g omega-3 fatty acids

B. Phospholipids

• when added to water – self-assemble and form a form a phospholipid bilayer – major component of the plasma membrane

• similar to fat molecules - glycerol + 2 fatty acids• modified through the replacement of one FA with a phosphate group (slight negative

electrical charge)• phosphate gp hydrophilic “head”• fatty acid gps hydrophobic “tails”

C. Steroids

• backbone is called cholesterol = 4 fused carbon rings• synthesized in the liver

• diversity through attached functional groupse.g. testosterone, estrogen, aldosterone, cortisol

3. Proteins

• nearly every dynamic function of a living organism depends on proteins•Greek – proteios = “first place”•more than 50% of the dry mass of most cells•numerous roles:

• structural – support of cells and tissues• storage - energy source • transport across cell membranes• hormones and their receptors – signaling• chemical messengers - signaling • antibodies - defense• metabolic role - enzymes

3. Proteins

•building blocks = amino acids

a.a. = amino group at 1 end, carboxyl at the other - between is a single C called the alpha carbon -the alpha carbon is assymetrical and is bound to: 1. H atom 2. R group

Side chain (R group)

Aminogroup

Carboxylgroup

carbon

• 22 amino acids available for human protein synthesis– 20 of them are coded for by our DNA

• the R group give the amino acid a unique physical and chemical character

• divided into three groups– polar amino acids– non-polar amino acids– electrically charged amino acids –basic or acidic

the 20 amino acids:1.non-polar:

1. Methionine – Met or M2. Phenylalanine – Phe or F3. Tryptophan – Trp or W4. Proline – Pro or P5. Glycine – Gly or G6. Alanine – Ala or A7. Valine – Val or V8. Leucine – Leu or L9. Isoleucine – Iso or I

2.polar: 1. Serine – Ser or S2. Threonine – Thr or T3. Cysteine – Cys or C4. Tyrosine – Tyr or Y5. Asparagine – Asp or N6. Glutamine – Glu or Q

3.acidic1. Aspartic acid – Asp or D2. Glutamic acid – Glut or E

4.basic1. Lysine – Lys or K2. Arginine – Arg or R3. Histidine – His or H

• amino acids joined together by a dehydration synthesis reactionforming a peptide bond = between the NH2 of 1 a.a. and the COOH of the next amino acid

2 a.a. dipeptide

3 a.a. tripeptide

4 or more a.a. polypeptide

Peptide bond

New peptidebond forming

Sidechains

Back-bone

Amino end(N-terminus)

Peptidebond

Carboxyl end(C-terminus)

• the 3D architecture is critical to protein function• 3D shape is determined by the sequence of amino

acids-i.e. the chemical properties of the amino acid

can determine whether the protein will twist or kink or be linear

•BUT – the physical environment can also affect 3D shape• e.g. pH, salt, temperature

•IMPORTANT: polypeptide does not mean protein!!!!

•polypeptides have 4 types of structures or conformations which affect their ultimate function

(b) A space-filling model

(a) A ribbon model

Protein conformation:

1. primary - a.a. sequence of polypeptidese.g. transthyretin – 127 amino acids-sequence is determined by the genetic code found in the DNA-if created randomly – then a 127 AA polypeptide could be made 20127 different ways!!

2. secondary – sections of the AA chain spontaneously fold into -helical coils or -pleated sheets

-the result of H bonding between regions of the amino acid chain

3. tertiary – the protein’s unique 3D shape-superimposed on the secondary structure-gives rise to the overall 3D shape and function of the protein-results from interactions between the R groups-3D shape is reinforced through the formation of disulfide bridges

Secondarystructure

Tertiarystructure

Hydrogen bond

helix

pleated sheet strand

Hydrogenbond

4. quaternary = joining of 2 or more polypeptides chains-aggregate into one functional macromolecule-individual polypeptide chains are called subunits

Collagen

Hemoglobin

Heme

Iron

subunit

subunit

subunit

subunit

MEDICAL APPLICATION: SICKLE-CELL DISEASE: A CHANGE IN PRIMARY STRUCTURE

• A SLIGHT CHANGE IN PRIMARY STRUCTURE CAN AFFECT A PROTEIN’S STRUCTURE AND ABILITY TO FUNCTION

• SICKLE-CELL DISEASE, AN INHERITED BLOOD DISORDER, RESULTS FROM A SINGLE AMINO ACID SUBSTITUTION IN THE BETA SUBUNIT OF THE PROTEIN HEMOGLOBIN

PrimaryStructure

Secondaryand TertiaryStructures

QuaternaryStructure

Function Red BloodCell Shape

subunit

subunit

Exposedhydrophobicregion

Molecules do notassociate with oneanother; each carriesoxygen.

Molecules crystallizeinto a fiber; capacityto carry oxygen isreduced.

Sickle-cellhemoglobin

Normalhemoglobin

10 m

10 m

Sic

kle-

cell

hem

og

lob

inN

orm

al h

emo

glo

bin 1

234567

1234567

4. Nucleic acids

• nucleotide: •5 carbon sugar (pentose)phosphate group (negative charge) located at the 5’ carbonorganic base located at the 1’ carbonsugar and the base is known as a nucleosidebases: 5 types: adenine (A)

cytosine (C)guanine (G)thymine (T)uracil (U)

• known as DNA, RNA• C,H,O,N,P• building blocks = nucleotides

Sugar-phosphate backbone5 end

5C

3C

5C

3C

3 end

(a) Polynucleotide, or nucleic acid

(b) Nucleotide

Phosphategroup Sugar

(pentose)

Nucleoside

Nitrogenousbase

5C

3C

1C

Nitrogenous bases

Cytosine (C)

Thymine (T, in DNA)

Uracil (U, in RNA)

Adenine (A) Guanine (G)

Sugars

Deoxyribose (in DNA)

Ribose (in RNA)

(c) Nucleoside components

Pyrimidines

Purines

There are two families of nitrogenous bases

1. Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring

2. Purines (adenine and guanine) have a six-membered ring fused to a five-membered ring

• polynucleotide chain - formed by a phosphodiester bond betweenthe phosphate (5’) of 1 n.t. and the sugar of the next (3’)

-phosphodiester bond is comprised of a phosphate group linking two sugars

• two major types of nucleic acids:1. RNA sugar = ribose2. DNA sugar = deoxyribose

ribose deoxyribose

HOCH2

H

OH

H

OH

O OH HOCH2

H H

H

O OH

OH

• so a DNA/RNA chain “grows” in one direction only

-5’ to 3’

Sugar-phosphate backbone5 end

5C

3C

5C

3C

3 end

(a) Polynucleotide, or nucleic acid

phosphodiester bond

A. RNAsingle chainbases: A, C, G and uracil

(U) in place of T3 major types: mRNA

tRNA rRNA

B. DNAdouble chain = double helix

2 chains held by hydrogen bonds between the bases

bases pair up in a complementary fashionA = TC G

sense strand (5’ to 3’) anti-sense strand

c. ATPindividual n.t’s can have metabolic functions

e.g. adenosine = adenine + ribose-adenine modified by adding three phosphates

major source of ATP = breakdown of glucose1 glucose molecule

36 ATP

glycolysisKreb’s cycleoxidative phosphorylation