Water, Acids, Bases and Buffering

Question 1

water

Answer 1

polar substance, the solvent of life performing many functions: transport, component of chemical rxns, control of body temp.

Question 2

water content of adipose tissue

Answer 2

contains little water; obese individuals have less body water, children have more

Question 3

polarity of water

Answer 3

the shared electrons of the H-O bond are attracted to the oxygen molecule, giving the H atoms a partial +ve charge and the oxygen atom a partial -ve charge

Question 4

properties of water

Answer 4

polarity allows polar molecules to dissolve, can from hydrogen bonds w/ polar compounds and “hydration shells” surround ions, hydrogen bonds are weak + constantly breaking/reforming so that solutes can move in sol’n and water can move through

Question 5

electrolytes

Answer 5

minerals that help maintain the body’s fluid balance; cations (K+, Na+) and anions (Cl-, HCO3-, PO4 2-)

Question 6

osmolality

Answer 6

the concentration of all dissolved solutes in the blood; water will move b/w compartments to keep the osmolality the same

Question 7

pH

Answer 7

a measure of the acidity or alkalinity of a solution with the equation of -log[H+]

Question 8

what is the pH range that needs to be maintained in the body for survival?

Answer 8

7.35-7.45

Question 9

acids

Answer 9

proton donors

Question 10

bases

Answer 10

proton acceptors

Question 11

acid dissociation

Answer 11

strong acids dissociate completely while weak acid dissociate only to a limited extend in water

Question 12

weak acid dissociation

Answer 12

HA H+ + A-

Question 13

Ka (equilibrium constant)

Answer 13

defines the tendency to dissociate, so the larger the Ka the greater the tendency to dissociate

Question 14

Henderson-Hasselbalch equation

Answer 14

pH = pKa + log [A-]/[HA], when the pH is equal to pKa, 50% of the acid is dissociated and this is when a buffer is most effective since there are equal amounts of acid and base present (still useful to ± pH unit of the pKa)

Question 15

buffers

Answer 15

combinations of weak acids and their conjugate base, can resist pH changes

Question 16

biologically important buffers

Answer 16

dihydrogen phosphate-hydrogen phosphate pair (ICF), carbonic acid-bicarbonate (blood), hemoglobin, etc

Question 17

carbonic acid-bicarbonate buffer system

Answer 17

metabolism produces large quantities of acid each day, the pH of blood would drop dramatically if not for buffers, esp. bicarbonate, the CO2 prod. from metabolism is the major source of acid and its buffer

Question 18

anion gap acidosis

Answer 18

“MUDPILES” the anions usually measured are chloride and bicarbonate and sodium is the measured cation

Question 19

metabolic acidosis

Answer 19

caused by excess prod. of keto-acids or lactic acid, or loss of bicarbonate which may happen w/ excessive diarrhea

Question 20

metabolic alkalosis

Answer 20

usually occurs from ingesting basic compounds (e.g. bleach) or retaining bicarbonate, or excessive vomiting

Question 21

respiratory acidosis

Answer 21

may be caused by conditions where the CO2 is retained, the pt is unable to exhale it, such as w/ pneumonia or emphysema

Question 22

respiratory alkalosis

Answer 22

occurs w/ hyperventilation due to stress, drug OD (e.g. salicylate) and fever (due to increased metabolic demands)