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Cell Chemistry (I) Inorganic Compounds Chemical Bonds Solutions and pH Introduction • Approach this ppt NOT as lecture notes but as an outline of the basic chemistry that you need to know to understand physiology and ease your way into biochemistry. • Most of the information can be found in Ch. 1, 2 or 3 of any college Anat. & Physiol. or college Biology textbook. • This ppt is NOT a substitute for reading the book. Chemical Bonds • Review the basic facts about: – Ionic bond – Covalent bond – Polar covalent bond – Hydrogen bond • The next slides illustrates some of these bonds Some Bonds Illustrated (Marieb, Fig. 2.9) Hydrogen Bonds Between Water Molecules (Becker Fig. 2.8) Solubilization of NaCl (Becker Fig. 2.10) Water: Significance in Physiology • Water is essential for life • It is a universal solvent in biological systems because of its: – Polarity, its cohesiveness, its temperature-stabilizing capacity and its solvent properties • Water molecules are held by Hydrogen bonds and these bonds account for its high surface tension, its high boiling point, high specific heat and high heat of vaporization • Cells are about 75-85% water by weight and one’s body weight is about 60% water. Terms Linking Solubility of Solutes in Water • The terms hydrophilic, hydrophobic, amphipathic and oil/water partition coefficient are often used to describe the solubility of a solute in water. • Hydrophilic solutes are usually polar (they have polar covalent bonds or ionic bonds) and because of their polarity dissolve readily in water • Hydrophobic solutes are non-polar, therefore, not soluble in water. They are soluble in organic solvents like benzene. They are rich in non-polar covalent bonds. • Amphipathic solutes have a region that is hydrophilic and another one that is hydrophobic. Surface Tension Allows Insect to Walk on Water Know examples of acids, bases & salts Know how to calculate, molarity, osmolarity and equivalentsK SOLUTIONS Solutions • Two components: – Solvent – Solute(s) • In physiology and in all biological systems: – the solvent is H2O – The solutes are many (hundreds) like 1. 2. 3. 4. Nutrients like amino acids, glucose Electrolytes (in physiology = anions & cations) Gases like O2 and CO2 Wastes like urea, creatinine, uric acid • Examples of solutions in the body – Plasma – Interstitial fluid – Synovial fluid – Urine Concentration of Solution • • Concentration is a ratio of the amount of solute(s) in a given volume of solvent Amounts are often expressed in – Grams (g) – Milligrams (mg) – Mole (m) or millimole (mM) – Milliequivalent (mEq) – Osmole (Osm) or milliosmole (mOsm) • Volume is often expressed in – Liters (L) – Deciliter(100 mL) – Milliliters (mL) – Microliters • Examples: – 0.9% NaCl or 135mmole/L NaCl or 135 mEq /L • GOAL: Given weight in grams, know how to calculate concentrations in molarity, osmolarity and equivalent Units for Concentration of Solutions • Percent (%): – 0.9% Sodium chloride (normal saline) – 153 mmole/L Sodium chloride (normal saline) • ?? • Other units commonly used in physiology – – – – • Do these have the same amount of NaCl? Justify your answer 0.1-0.4 mg/dL creatinine 70-110 mg/dL glucose 285-295 mOsm/Kg H2O (For what? 136-142 mEq/L Sodium Units for amount of gas – 80-105 mmHg – Volume % • Why should I care about these units? – You will constantly run into them in physiology, in reading patients charts and in reading cases. Inorganic Compounds • Most of the chemical in your body and the foods that you consume are compounds that are classified as: – Inorganic or – Organic • Inorganic compounds – Small – Lack carbon atom (some exceptions? ) – Most are composed of minerals like K, Ca, P, Mg, Fe – Their atoms are held by ionic bonds • Characteristic of ionic bonds – They are weak ( easily broken, no enzyme required) Common Examples of Inorganic Compounds Significant in Physiology • Sodium chloride: – NaCl • Calcium phosphate – (Ca)3(PO4)2 • Potassium iodide – KI • Sodium bicarbonate – Na(HCO3) • Hydrochloric acid – HCl • Sodium hydroxide – NaOH • Magnesium hydroxide – Mg(OH)2 • Calcium chloride – CaCl2 Sources of Electrolytes in Physiology • In physiology, anions and cations are collectively called electrolytes • Salts – NaCl, KI, Na(HCO3) • Acids (organic and inorganic) – HCl, H2CO3 – Lactic acid and Acetoacetic acid • Bases HCO3OH- Ionization of Salts, Acids and Bases • In H2O the ionic bonds in acids, salts and bases break and the atoms dissociate into ions (or ionize). • Examples – Replace question marks with correct answer/s NaCl -> Na+ + ClKI -> ?? H2CO3 --> H+ + HCO3Mg(OH)2 ?? What to Do! • Look up/review significance of listed ions in physiology or cell biology. – Example: I- (iodide) is essential for thyroxine (T4) synthesis by the thyroid gland. T4 regulates basal metabolic rate. Now do the same for: + H + K + Na Cl ++ Fe ++ Ca Questions? • Which one is OR which ones are: – – – – A) acid(s) B) base(s) C) salt(s) D) electrolytes 1. 2. 3. 4. 5. 6. 7. 8. 9. HCl H2CO3 KI (potassium iodide) Na(HCO3) Ca3(PO4)2 NaCl Na(OH) Mg(OH)2 H2CO3 Inorganic Acids, Bases and Salts • Acids, bases and salts in the diet are major sources electrolytes (anions and cations) in body fluids. • In H2O acids, bases and salts ionize or dissociate into anions and cations. • Examples: – Na:Cl -> Na+ + Cl– H:Cl -> H+ + Cl– Na:OH -> Na+ + (OH)- • All ions are not NAKED. They are surrounded by a “shell” of H2O (a hydration shell) • Hydration shell Illustrated on next slide. Solubilization of NaCl (Becker Fig. 2.10) ACIDS, BASES AND PH Acid: Definition & Examples • Substances () that ionize (dissociate) into one or more Hydrogen ion (H+) PLUS one or more anion(s) • H+ is also called a proton. • Acids are also defined as a proton donors or substances that add proton(s) to a solution. • Examples of: – Inorganic acids; ---?? – Organic acids: ---?? Significance of H+ in Solutions • H+ concentration in a solution affects the acidity or alkalinity of the solution: pH =log 1/[H+] = -log [H+] • Note log scale and inverse relationship between [H+] and acidity/alkalinity of a solution • ? Fill-in blank spaces with the correct term – The higher the [H+] the more ---? the solution – The lower the [H+] the more ---? The solution pH: Note Log Scale Know pH of Some Foods Household Goods Base: Definition and Examples • Substance (electrolyte) that ionizes (dissociates) into one or more hydroxide (OH-) ion(s) PLUS one or more cation(s). • Also defined as substances that accept or bind to or remove free proton(s) from solutions. • HCO3- (What ion is this?) is a major base in body fluids. Salt: Definition and Examples • Substance (electrolyte) dissociate into cations (??) and anions (??) neither of which (??) is H+ or (OH)– Examples of salts? • Products of reaction between an acid and a base • Example ofsuch a reaction – Na(OH) + HCl -- NaCl + H2O Body Fluid pH • • • • Normal body fluid pH is between 7.35 to 7.45. pH below 7.35 is a condition called acidosis pH above 7.45 is a condition called alkalosis Two organs collaborate to maintain normal body fluid pH: – The lungs and the kidneys • The lungs do so by regulating the excretion rate of CO2 and the kidneys, by regulating the excretion rate of HCO3- ions. Questions 1. Gastric juice (produced by the stomach) has a pH of 5.0 and plasma pH is 7.0. – A) Which one has the lowest H+ concentration: Plasma or gastric juice? – B) The difference in concentration is how many times lower? 2. Mr. John Doe has a kidney disease that impairs excretion of HCO3-. – A) Would his plasma HCO3- Concentration increase, decrease or remain within the normal range? – B) Is he likely to end up with acidosis, alkalosis or neither? Justify your answer. 3. Would you expect hyperventilation or hypoventilation to impact your body fluid pH? Justify your answer CHEMISTRY I THE END