Chemical LevelWednesday, September 05, 201212:09 PMComposition of Matter Matter - Anything that occupies space and has a massAtoms are the building blocks of matter (charge = neutral) Inert Elements - Atoms with complete valence shells (chemically inert, unreactive)Chemically-Reactive Elements - Atoms with incomplete valence shells (unstable, reactive) Chemical Level -Biochemical reactions occur in the cells to define physiology (study of function)-Explained by reactivity of atoms to achieve stability-Atoms strive to complete outermost shell (valence shell) "Octet Rule" - strive to complete 2nd & 3rd shell with 8 electrons (not 1st shell b/c it can only accommodate 2 electrons)-Atoms has 3 subatomic particles: Protons (+ charge), Neutrons (no charge), Electrons (- charge)Atomic nucleus = positively chargedAtomic number = # of protons in nucleus = # of electronsElectrons located in orbitals/shells around the nucleusOverall charge of an atom = 0 Covalent Bonds - electrons shared to attain stability-Polar covalent-Non-polar covalentIonic Bonds - Complete transfer of electrons -Atom donating becomes CATION (positive charge)-Atom accepting becomes ANION (negative charge)Hydrogen Bonds - Weak bond between hydrogen atoms -With the exception of the noble (inert) gases which come with complete valence shells, atoms achieve stability by completing their outermost shell through chemical reactions (through which atoms may gain, lose, or share electrons to achieve stability).Atom GAINS Electron > ANION (- charge)Atom LOSES Electron > CATION (+ charge)-Anions & Cations form Ionic Bonds-When atoms share electrons to achieve stability, the bond formed is a covalent bond-Non Polar > Equal sharing of electrons-Polar Covalent > Unequal sharing of electrons > The atom that pulls the shared electrons is referred to as an Electronegative Atom (δ-), other atom referred to as an Electropositive Atom (δ+)-POLAR COVALENT BOND is always ELECTROPOSITIVE (with hydrogen binds will always form other electronegative atoms)-Hydrogen bonds are molecular bonds that form to hold larger molecules together (Macromolecules) -Based on the biochemical reactions occurring in the cells2 Categories:-Inorganic Compounds - do not contain carbon chains (except CO2 & CO)-Organic Compounds - Contain carbons that are covalently bonded Water:-70% cells-Universal Solvent-High Heat capacity (absorbs body heat) -High heat of vaporization (cools body down - water evaporates (sweat))-Cushions major organs (brain) Acids - Substances that release Hydrogen Ions (H+) "Proton Donors"-Blood pH is maintained b/t 7.35-7.45 (actions of enzymes in physiological processes)-Acidosis - increase in H+ in bloodBases - Substances that accept H+ "Proton Acceptors"-Acid-base balance is regulated by buffers - chemicals that resist abrupt changes in pH -Inorganic compounds in the human body:1. Water - "Universal Solvent"2. Acids - "proton donors", release H+ (a proton), [H+] determines pH of a solution-pH = 1/[H+], High [H+] = Low [pH], Inverse relationshipBlood: 7.35-7.45, optimum body function due to presence of enzymesTo maintain homeostasis of blood pH, buffers are used in the body Acidosis (Decrease in blood pH = 7.15), Buffer system will BIND H+ to raise the blood pH to normalAlkalosis (Increase in blood pH = 7.56), Buffer system will RELEASE H+ to drop the blood pH to normal Salts - Ionic compounds that dissociate completely in water to give Cations & Anions Organic Compounds:-Carbohydrates-Monosaccharaides: general formula (sweet & soluble in water)-Hexose - glucose, fructose, galactose-Pentose - deoxyribose, ribose-Disaccharides: composed of 2 hexose sugars (sweet & soluble in water)-Maltose (grain sugar)-Sucrose (table sugar)-Lactose (milk sugar)-Polysaccharides: composed of long chains of glucose (storage)-Starch - plant cells-Glycogen - animal cells-Lipids - Hydrophobic substances -Neutral Fats (Triglycerides): most abundant form of fat in human body, Fats (solid)/Oils (liquid)-Saturated - single covalent bonds (solid - ex. butter)Low density lipoprotein (LDL) "BAD CHOLESTEROL"High density lipoprotein (HDL) "GOOD CHOLESTEROL"-Unsaturated - at least one double covalent bond (liquid - ex. olive oil)-Phospholipids: glycerol backbone & 2 free fatty acid chains & phosphorus containing group-Steroids: derived from cholesterol-Eicosanoids-Proteins-Nucleic Acids -4 Types of Organic compounds in the human body:-Carbohydrates (CH2O)-Monosaccharaides-Disaccharides-Maltose = Glucose + Glucose (Grain sugar)-Sucrose = Glucose + Fructose (Table Sugar)-Lactose = Glucose + Galactose (Milk Sugar)-Polysaccharides-Lipids (hydrophobic, insoluble in water)-Neutral Fats - Abundant in the human diet-Unsaturated = Liquid-Saturated = SolidTransported in the aqueous environment In the human body covered by proteins to form Lipoproteins: Lipid:Protein, Proteins are more dense than liquids-Phospholipids-Steroids-Eicosanoids -Very Low Density Lipoprotein (vLDL) - Triglyceride (major, neutral fats)Most common in human diet, vLDL transports triglycerides to cells for energy production, for storage and for cushioning of organs in the bodyFat (triglycerides) is the most common and efficient form of stored energy1g fat --> yields 9 Kcal1g glucose --> yields 4 Kcal1g protein --> yield 4 Kcal -Low Density Lipoprotein (LDL) - Bad CholesterolLipids > ProteinsTransport s cholesterol to the plasma membrane (cholesterol maintains integrity of the plasma membrane)Transports cholesterol to steroidogenic cells for the synthesis of the steroid hormones (testosterone, estrogen, cortisone, etc.)Too much cholesterol in the form of LDL is bad for you - Cholesterol in LDL's settles in the internal walls of the blood vessels to form plaque.-Therosclerotic Plaques: In large blood vessels partially block the blood vessels and impede blood flow --> Result = Hypertension/High blood pressure, Heart beat increases to compensate for the increase in resistance to blood flow --> Result = Enlarged Heart/Cardiomegaly --> Cardiomegaly can result in heart failure-If an atherosclerotic plaque dislodges from the internal wall of a blood vessel, it floats in the bloodstream --> Free-floating plaques = Emboli --> If Emboli lodges in smaller blood vessels, theyocclude the blood vessels/prevent blood flow through the occluded blood vessels, hence tissues served by the occluded blood vessels die due to lack of oxygen & nutrients-Cerebral vessels (in brain) and the coronary vessels (of heart) are
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