Module 2.1: Acid-Base Balance

Question 1

Why is maintaining pH important? (generally)

Answer 1

• Regulates the chemical environment necessary for optimal cellular function

Question 2

Why is maintaining pH important? (Specific functions)

Answer 2

Maintains enzyme activity, supports oxygen transport, ensures electrolyte balance, prevents tissue damage, facilitates waste removal

Question 2

How is correct pH balance maintained?

Answer 2

Carried out by a variety of buffer systems
* Imbalances can lead to serious conditions

Question 3

what does acidity measure?

Answer 3

concentration of H+ ions in solution

Question 4

What are the mechanisms in acid base balance?

Answer 4

buffer systems (molecular control of free H+), respiratory system (CO2 exhalation), Renal system (H+ excretion into filtrate and then urine)

Question 5

what are buffers?

Answer 5

substances that help stabilize pH by neutralizing excess acids or bases

Question 6

what do buffer systems do?

Answer 6

• Provide immediate pH regulation and can act within seconds
• Prevent rapid, drastic changes in pH by withholding or releasing hydrogen ions

Question 7

what are the key buffers?

Answer 7

• Protein Buffers
• Phosphate Buffers
• Bicarbonate Buffer System (carbonic-acid bicarbonate buffer system)

Question 8

what are proteins composed of?

Answer 8

chains of amino acids
* Each chain at least one carboxyl group (-COOH) and one amino group (-NH2), sometimes many of both

Question 9

what can proteins do?

Answer 9

bind to or release hydrogen ions

Question 10

what does the amino group do in protein buffer systems?

Answer 10

Amino Group acts like a base and combines with H+ (increase pH by removing H+)

Question 11

what does the carboxyl group do in protein buffer systems?

Answer 11

Carboxyl Group acts like an acid to release H+ (decrease pH)

Question 12

as anions, where do phosphates regulate pH?

Answer 12

mainly in intracellular fluid (ICF) but also in extra-cellular fluids (ECF)

Question 13

what are the two kinds of phosphate anions in phosphate buffer systems?

Answer 13

• Monohydrogen phosphate [HPO4]2-
• Dihydrogen phosphate (H2PO4-)

Question 14

how do phosphate buffer systems work?

Answer 14

Involved in major metabolic pathways in cells and buffer reactions that produce H+ or OH-

Question 15

how does monohydrogen phosphate work

Answer 15

weak base, binds to hydrogen ions (one it bonds it becomes a dihydrogen phosphate)

Question 16

how does dihydrogen phosphate work?

Answer 16

weak acid, buffering strong bases (becomes a monohydrogen phosphate)

Question 17

what is the equilibrium reaction in carbonic-acid bicarbonate buffer system?

Answer 17

• When ↑ pH, low H+ concentration; equation shifts right
• When ↓ pH, high H+ concentration; equation shift left

Question 18

Where does carbonic acid and H+ ions come from?

Answer 18

• 1) Cells produce CO2 and H+ ions as a byproduct of metabolism
• 2) CO2 dissolves in plasma and reacts with water
• 3) Carbonic Acid quickly dissociates into bicarbonate and hydrogen ions

Question 19

when are these reactions taking place and where?

Answer 19

all the time. inside the cell and extracellular fluid

Question 20

how is carbon dioxide transported?

Answer 20

in plasma (very slow process due to a small amount of carbonic anhydrase) and in RBCs (attach to hemoglobin)

Question 21

where does carbon dioxide get transported to?

Answer 21

alveolar space in the lung to be removed

Question 22

how is CO2 removed from plasma? how does this change in RBCS

Answer 22

moves down its concentration gradient from site in the blood to alveolar space to be exhaled and removed (slowwww). process in rbcs is much quicker

Question 23

what can breathing do?

Answer 23

release Co2 produced by cells to prevent the pH from going too low