The Body As A Bio-environment

Question 1

Waters role in living organisms

Answer 1

• solvent of polar molecules
• temperature buffer due to high SHC
• metabolite - water is reactant

Question 2

Healthy pH level in body

Answer 2

7.35 - 7.45
- pH = -log[H3O]

Question 3

Acid vs base

Answer 3

Acid - proton donor
Base - proton accepter

Question 4

Strength of acids and bases - dissociation constant and equilibrium constant

Answer 4

Acid + base >< Ca + Cb
Ca: conjugated acid
Cb: conjugated base
Ka: equilibrium constant
Ka = (Ca*Cb)/acid
Strong acid: larger Ka, weaker Cb

Question 5

Examples of strong acids and bases

Answer 5

Acids: HCl, HBr, HI, HClO4 - most of group 7
Bases: group 1A metal hydroxides, heavy group 2A metal hydroxides

Question 6

Weak acids and bases

Answer 6

Acids: HCOOH, CH3COOH, HF
Bases: NH3, H2O, C5H5N

Question 7

Le Chatelier’s principle (in chemistry)

Answer 7

• when a system at equilibrium is subjected to change in concentration, temperature, volume or pressure, the system counteracts the effect of the applied change and a new equilibrium is established

Question 8

Buffers

Answer 8

• aqueous solution of weak acid and its conjugate base or vice versa
• pH changes very little when small to moderate amount of acid is added to it so prevents pH changes
• used to keep pH constant
• eg blood

Question 9

Blood as a buffer system / other methods of pH regulation in the body

Answer 9

• Bicarbonate/Carbonic acid is main buffer in blood
• protons constantly generated by metabolism
• kidney and lungs regulate pH via excretion
• Acidosis: pH<7.35, kidneys fail to excrete excess acid, diarrhoea, hypoventilation
• Alkilosis: pH>7.45, repeated vomiting, hyperventilation

Question 10

Acid build up

Answer 10

• lactic acid is end product of anaerobic oxidation of glucose
• more energy needed in muscles than provided