UNIT 2: Chemistry of the Human Body

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UNIT 2 Chemistry of the Human Body

• Compounds
• Metabolism
• Nutrition

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WHY STUDY CHEMISTRY?

• Chemistry is the ultimate (basic) cause of all
  physiological processes
• Interactions of atoms produce chemical changes
  that result in compounds being broken down, built
  up, changed
• Chemical reactions involve a transfer of energy
  between the compounds makes and breaks chemical
  bonds that hold the atoms together and the
  energy
• We are made of many non-living substances
  reacting with one another to give us all of our
  characteristics of life
• Metabolism, growth, reproduction, assimilation,
  energy use, movement etc.

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Major elements of Human Body

• Macroelements
• Big Four (by weight)
• Oxygen 65
• Carbon 18.5
• Hydrogen 9.5
• Nitrogen 3.2
• 96 Total of Four
• Other Elements
• Ca, P, K, S, Cl, Na, and Mg
• These elements make up 99.9 of the human body

• Trace elements
• Elements needed in extremely small amounts but
  still very important
• Co, Cu, F, I, Fe, Mn, Zn
• Too much copper (Cu) ? Wilson Disease
• Too little copper ? Menkes Disease
• Kinky Hair syndrome
• Too much iron (Fe) ? hemochromatosis
• Too little iron ? anemia
• Unable to make hemoglobin correctly
• Too little Iodine Goiter ? Thyroid condition

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Basic atomic structure

• Protons - charge atomic number
• Found in nucleus
• Specific for element All atoms of the same
  element have the same of P
• Neutrons No electrical charge
• of P of No atomic mass
• Isotopes atoms of the same element with a
  different atomic mass
• of neutrons differ
• Can be Radioactive unstable atoms that release
  energy and particles as they decompose
• Electrons (-) charged particles
• Found outside the nucleus in energy levels
  (orbitals)
• Determine reactivity of atoms Rule of 8
• Ions charged particles because of a gain or
  loss of electrons

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RADIOACTIVE ISOTOPES

• Half-life the amount of time it takes for a
  radioactive substance to decay half of its mass
• Diagnostic Tracers (follows specific substances
  through the body)
• PET Scans Brain studies
• Angiography
• Barium for Digestive system
• Medical Treatment
• Radioactivity can kill cells
• Cancer treatment radioactive Iodine treats
  Thyroid Cancer

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RADIOACTIVE ISOTOPES

• Ionizing Radiation
• Health problem of radioactive isotopes in
  environment
• Can cause cell death, cancer (mutations in body
  cells) and birth defects (mutations in
  reproductive cells
• Mutations changes in DNA (genes)
• Free radicals ions formed from radiation that
  interfere with metabolism
• Anti-oxidants certain substances in food that
  help prevent the formation of free radicals
• Nuclear Waste, Medical Wastes
• Always exposed to radiation certain levels are
  considered safe

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Metabolism

• Metabolism the sum of all chemical reactions in
  the body
• Reactants interact (react) with one another to
  form products
• Anabolism reactions that form larger, more
  complex molecules
• Requires an input of energy (endergonic)
• Dehydration synthesis reactions that build
  large organic molecules form water
• Catabolism reactions that break down larger
  molecules into simpler forms
• release of energy (exergonic)
• Hydrolysis break down of large organic
  compounds into basic units (monomers) split
  water
• Anabolism Catabolism Metabolism
• Each reaction requires a specific enzyme to happen

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Enzymes

• Enzymes biological catalysts
• Speed the rate of reactions by lowering the
  activation energy
• Activation energy energy needed for a chemical
  reaction to happen
• Enzymes are proteins
• Lock and Key Model
• Each enzyme has a definite, specific shape (lock)
• Substrate reactants involved in the enzymatic
  reaction (key)
• Substrate must fit into active site of enzyme for
  reaction to occur
• One enzyme ? one specific reaction
• Enzymes are not changed during the reaction
• Can be recycled

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Enzymes

• Coenzymes smaller organic molecules that are
  needed for a proper fit of an enzyme to substrate
• Vitamins
• Cofactors ions needed for proper fit of
  enzyme/substrate
• Minerals
• Denaturation the change of a proteins shape
• Change the shape, change (usually ruin) the
  function
• Once it happens, usually will not return to
  normal
• High temperatures fever
• Wrong pH hydrogen ions, hydroxide ions
  interfere with shape and substrate/enzyme
  interaction
• Salt concentration ions interfere

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Inorganic substances

• Do not contain Carbon
• CO2 is sometimes considered exception (our text
  lists as inorganic)
• Now most scientists list this as organic because
  it is the ultimate source of all organic
  compounds
• Plants turn CO2 into organic compounds by
  photosynthesis ? passed to all other organisms
  through consumption
• Know significance of water, oxygen, carbon
  dioxide and salts

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Inorganic substances

• Water (H2O)
• Most abundant substance in body approx 2/3 of
  weight
• Highly polar molecule
• Partial charges on opposite ends of molecule
• Acts like a molecular magnet
• Chief reason why water is so important
• High Heat Capacity takes a lot of energy to
  change the temperature of water
• Helps maintain a stable body temperature
• High Heat of Vaporization takes a lot of heat
  energy to turn liquid water into water vapor
• Evaporative cooling cooling by evaporating
  water
• Sweating uses body heat to evaporate water
  body loses heat energy and cools
• Expands when it freezes (negative)
• Kills cells when cellular fluid freezes
• Frostbite
• Necrosis tissue death black loss of structure
• Infection gang green

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Inorganic substances

• Universal Solvent dissolves many substances
  (polar and ionic compounds)
• Dissociation the pulling apart of ionic
  compounds by water
• NaCl (salt) ? Na Cl-
• Forms electrolytes - ions necessary for
  metabolism
• pH scale to measure the acidity of a substance
• 0 14
• Each step is 10X difference
• Acids substances with more H ions than OH-
  ions
• Below 7
• Lower the number stronger the acid
• Bases substances with more OH- ions than H
  ions
• Above 7
• Higher the number, stronger the base
• Neutral substances - H OH-
• pH 7
• Dissociation of water (H2O ? H OH-)

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Inorganic substances

• pH (continued)
• Neutralizaiton reaction mixing an acid and a
  base to form a neutral solution
• Forms salt and water
• HCl (A) NaOH (B) ? NaCl (S) HOH (W)
• Buffers substances that regulate the pH of a
  solution by absorbing or releasing H ions
• Example of Buffering System
• Blood Normal pH 7.4 - 7.7
• Alkalosis pH too high
• Acidosis pH too low
• Uses bicarbonate ion (HCO3-) as buffer
• CO2 combines with water to form carbonic acid
  (H2CO3)
• Carbonic acid dissociates into bicarbonate ions
  (HCO3-) and hydrogen ions (H)
• H2CO3 ?? HCO3- H
• If pH is too low, reaction proceeds to left
  forms carbonic acid, lowers amount of H ions
  raises pH
• If pH is too high, reaction proceeds to right
  forms bicarbonate ion increase H ions, lowers
  pH

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Inorganic substances

• Oxygen (O2)
• Used to release energy stored in food
• Taken into body by respiratory system
• Diffuses into blood at alveoli in lungs
  microscopic air sacs at the end of the bronchial
  tree
• 21 of atmosphere
• Final electron acceptor in aerobic respiration
• Glycolysis Glucose ? pyruvic acid
• Happens in cytoplasm
• Produces 2 ATP NADH
• Krebs (Citric Acid) Cycle
• Happens in mitochondria
• Produces 2 ATP NADH and FADH
• Electron Transport Chain
• Happens in mitochondria
• NADH and FADH produced in glycolysis and Krebs
  Cycle travel to e- transport chain
• Electrons are passed down the chain and energy is
  used (transferred) to make ATP 34 ATP

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Inorganic substances

• Without Oxygen anaerobic respiration
• Lactic Acid fermentation
• Only 2 ATPs produced not enough for long term
  use
• Lactic acid produced as by-product interferes
  with proper muscle contractions (cramps and
  fatigue)
• Oxygen Debt oxygen needed to replenish ATP
  supply and get rid of lactic acid build-up in
  muscles
• Carbon Dioxide
• Some consider it to be organic
• Ultimate (original) source of carbon for all
  organic compounds
• Waste product of cellular metabolism
• Produced when glucose is broken down during
  aerobic respiration
• Lowers pH by forming carbonic acid
• Buffered by bicarbonate ions (see pH notes)
• Salts metal ionically bonded to nonmetal
• Dissociates in water
• Forms ions (electrolytes) necessary for metabolism

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Organic compounds

• Compounds that contain carbon, hydrogen and
  usually oxygen
• Accounts for most of our solid part
• Four main groups carbohydrates, lipids,
  proteins, nucleic acids
• Basic Information
• Make up most of the solid parts of our bodies
• All are composed of repeating basic units called
  monomers
• Put together by dehydration synthesis reactions
  covalently bond by removing water molecule
  (anabolic)
• Broken down by Hydrolysis reactions break bonds
  by splitting water (catabolic)

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Organic compounds

• Carbohydrates
• Contain C, H, and O (HO is 21) ? carbo (carbon)
  - hydrate(water)
• Monomer monosaccharides (glucose, fructose,
  galactose)
• Glucose is main source of energy for cells
• Broken down by aerobic respiration to transfer
  energy stored in glucose to ATP
• Blood sugar level is conc. of glucose in blood
• Sucrose disaccharide table sugar two
  monosaccharides bonded together
• Polysaccharide long chains of monomers
  (glucose) bonded together
• Glycogen stores energy for in between meals
• Stored in liver and muscle tissue
• Starch plant long term energy storage
• Found in pasta, potatoes, grain (breads)
• Cellulose makes up cell walls
• Not able to be digested
• Helps things go through the digestive tract
  Fiber
• Main Use immediate energy and short term energy
  storage
• If not all the glycogen is used up, then the body
  stores it in the more stable form of fat.

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Organic compounds

• Lipids fats triglycerides
• Elements C, H, and O (lot more C and H than O) ?
  long chains of H and C (hydrocarbons)
• Monomer is glycerol 3 fatty acid chains
• Energy is stored in C-H bonds of fatty acids
• Saturated fats no double bonds between C in
  fatty acid chains max. amt. of H
• Linked to vascular disease atherosclerosis
• Animal fats, coconut and palm oils
• Unsaturated fats double bonds between C in
  fatty acid chains missing Hs
• Healthier
• Plant oils peanut and corn oils
• Main function long term energy storage
• Can be broken down for energy if not enough
  calories from carbs are taken in
• Actually stores more energy than carbs per unit
  of weight
• Steroids lipids with four rings of hydrocarbons
• Cholesterol fat that is produced by liver and
  taken in by diet too much can clog arteries ?
  heart disease
• Testosterone, estrogen sex hormones
• Stimulates changes that occur during puberty

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Organic compounds

• Proteins
• Elements C, H, O and N (sometimes S)
• Monomer amino acids
• Central Carbon, amino group (NH2), carboxyl group
  (COOH) and R group
• R Group only thing that differs between amino
  acids
• Linked together by peptide bonds
• Order of amino acids determine shape, function
  and type of protein
• Polymer polypeptide long chains of amino acids
• Hemoglobin protein found on red blood cells
  that is necessary to carry oxygen through the
  blood
• Insulin protein that acts as a hormone to tell
  liver to synthesize glycogen
• Functions most varied in biological systems
• Structural actin and myosin in muscle tissue
• Enzymes regulate metabolism
• See enzyme notes

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Organic compounds

• Nucleic Acids (genetic information)
• Elements C, H, O, N and P
• Monomer nucleotide
• Consists of 5 C sugar, phosphate group and
  nitrogenous base
• Nitrogen bases Adenine, Thymine (DNA only),
  Uracil (RNA only), Guanine, Cytosine
• Polymers chains of nucleic acids DNA and RNA
• Order of the bases are essential for function
• DNA (deoxyribonucleic acid) double stranded
  deoxyribose sugar bases are A, T, C and G
  master copy found in nucleus
• RNA (ribonucleic acid) single stranded ribose
  is sugar bases A, U, C and G copy of DNA can
  travel to cytoplasm
• ATP (adenosine triphosphate) energy molecules
  used by cells
• Also a nucleic acid
• Adenosine (adenine ribose) 3 phosphate groups
• Energy is stored between phosphate groups
• Break bonds to release energy, form bonds to
  store energy

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Organic compounds

• From Gene to Protein
• Gene a segment of DNA that codes for the
  production of a specific protein
• Controls cell activities by what proteins
  (enzymes) they code for
• Order of bases determine what amino acids
  sequence is used in protein ? function of
  individual proteins
• Transcription copying the DNA gene to a strand
  of mRNA
• Translation ribosomes assemble amino acids into
  the correct sequence
• Knows the sequence by the mRNA code
• Problems Mutations
• Def changes in the DNA sequence
• Change DNA sequence ? change order of amino acids
  in protein ? change shape of protein ? destroy
  function
• Sickle Cell anemia point mutation
• Changes hemoglobin molecules one amino acid is
  different in polypeptide inaffective at
  carrying oxygen
• Frameshift mutations changes entire amino acid
  sequence after mutation
• Cancer mutations in genes that control cell
  cycle
• Oncogenes turned on to make cells divide too
  quickly
• Tumor Suppressor genes turned off to make cells
  divide too quickly
• Tumor mass of nonfunctional cells that starve
  surrounding good cells

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Nutrition

• Def how we obtain and use the raw materials
  necessary for proper functioning of the human
  body through diet
• Organic compounds must be broken down into
  simplest form before taken into the body
• Digestion makes this happen
• Not in the body until absorbed across barrier
  into bloodstream usually in small intestines
• Carbohydrate utilization
• Absorbed as monosaccharides glucose, fructose
  and galactose
• Fructose and galactose are usually turned into
  glucose by liver
• Glucose is used by cells for energy (ATP
  synthesis)
• Not all glucose is used at once liver stores
  some as glycogen
• Glycogen is broken down for a continuous supply
  of glucose in blood
• If not all the glycogen is used, body turns it
  into fat and stores it
• If there is not enough glycogen between meals,
  body will burn fat and use it for energy
• Requirements
• Minimum 125 175 grams per day
• Normal 200 300 grams per day

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Nutrition

• Lipid metabolism
• Must be broken down into glycerol and fatty acid
  chains before entering body
• Can be used for structure (cell membrane
  phospholipids) or long term energy storage
• Cholesterol is used in cell membranes
• Steroids are used as hormones
• Beta Oxidation change fatty acid chains into
  compounds that can be utilized by cell
  respiration for energy
• Acety Coenzyme A
• Ketone bodies form from other parts acetone
• Can make breath and urine smell fruity sign of
  starvation
• Can also be changed into acetyl coA for energy
• Essential Fatty acids those that cannot be
  produced by body must be taken in through diet
• Linolenic acid arachidonic acid
• Should not exceed 30 of caloric intake

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Nutrition

• Protein Metabolism
• Broken down into amino acids before absorbed
• Reassembled into proteins necessary for the body
• Mainly structural proteins, enzymes, clotting
  factors, cell identification (antigens),
  antibodies, hormones, regulate water balance
• Can be used as an energy source if needed
• Essential amino acids 8 amino acids that the
  body cannot produce
• Isoleucine, leucine, lysine, methionine,
  phenyalanine, threonine, tryptophan, valine
• PKU genetic disorder that does not allow the
  body to metabolize phenylalanine
• Accumulates and can cause mental retardation
• Warnings on food products (artificial sweeteners)
• Vegetarians must be careful because plants do not
  always contain complete proteins

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Nutrition

• Using protein for energy
• When not enough carbohydrates are present, body
  will break down amino acids for energy
• Deamination removing amino groups from amino
  acids
• Contains Nitrogen
• Amino groups converted into urea ? removed in
  urine
• Energy Values of Food
• Calories units of heat (energy)
• Physics 1 calorie amt of heat needed to raise
  the temperature of 1 gram of water by 1o Celsius
• Food 1 calorie 1000 physics calories
  (kilocalorie)
• Determined using a bomb calorimeter
• BMR basal metabolic rate
• Amount of energy needed for basic functioning of
  body measured when a person is awake, at rest
  after a night of fasting
• Energy Balance compares how much energy is
  taken in to how much energy is used
• Excess energy is stored as fat in adipose tissue
• Obesity over 20 overweight
• See Body Mass Index Clinical Appliation 18.1 P.
  731

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Nutrition

• Vitamins small organic compounds necessary for
  normal metabolic processes
• Cant be made by body ? must be supplied by food
  we eat
• Fat Soluble Vitamins A, D, E, K
• Disorders night blindness, rickets
• Water soluble vitamins B (Thiamine B1,
  Riboflavin B2, Niacin, B6, Pantothenic acid,
  Cyanocobalamin B12, Folic Acid, Biotin), C
  (ascorbic acid)
• Disorders - scurvy
• Minerals inorganic elements that are essential
  in human metabolism
• Calcium and phosphorus make up 75
• About 4 of body weight concentrated in teeth
  and bones
• Ca, P, K, S, Na, Cl,
• Trace elements Fe, Mn, Cu, I, Co, Zn, F, Cr

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Healthy Eating

• Needs to provide sufficient energy, essential
  fatty acids, essential amino acids, vitamins and
  minerals
• RDA recommended daily allowances
• Set up by nutritionists to help make sure people
  are getting a balanced diet
• Found on food labels
• Food Pyramid placing foods into groups
• 1950s 4 food groups 1940s 8 food groups
  1920s had group devoted to sweets
• See Figure 18.16 P. 746 (1992)
• Look on labels to help determine how healthy
  foods are
• Most abundant ingredient listed first
• Focus on calories

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Healthy Eating

• Disorders
• Malnutrition lack of essential nutrients or
  failure to use them
• Can be because of not enough or too much
• Can be genetic still present with healthy diet
• Starvation no food intake
• 50 70 day survival rate for healthy humans
• Body begins to digest itself
• 1 day ? sugars and starches are gone
• Next uses fat, then protein (muscle tissue)
• Metabolism slows
• Marasmus lack of nutrients look like living
  skeleton
• Kwashiorkor the evil spirit which infects the
  first child when the second one is born
• Common after baby is weaned from breast milk
• Ascites belly swells from fluid build up
• Anorexia Nervosa self-imposed starvation
• 1 out of 250 adolescents ? 95 female
• Ritualized eating behavior, brittle hair,
  irregular heart rate, constipation, chiliness,
  low blood pressure, lanugo
• 15 to 21 death rate
• Bulimia binging and purging