Transcript SOP-CelChem

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
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•
•
•
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