Acid/Base Physiology

Question 1

Ka = _________.

Answer 1

([H+][A-]) / [HA]

Question 2

What is the Henderson-Hasselbach equation?

Answer 2

pH = pKa + log([A-]/[HA])

Question 3

CO2 can be thought of as the conjugate acid of __________, because ________.

Answer 3

HCO3-; CO2 gets rapidly converted to H2CO3 by carbonic anhydrase

Question 4

Give the adjusted Henderson-Hasselbach equation for arterial CO2 and bicarbonate.

Answer 4

pH = 6.1 + log([HCO3-]/[0.03xPaCO2])

Question 5

Venous pH is only slightly higher than arterial pH because ___________.

Answer 5

deoxyhemoglobin is a good buffer

Question 6

Acidemia is defined as _______.

Answer 6

blood pH

Question 7

Alkalemia is defined as _________.

Answer 7

blood pH > 7.4

Question 8

Most acidosis is caused by _________.

Answer 8

insufficient ventilation

Question 9

For every 10 Torr increase in CO2, pH _______.

Answer 9

decreases by 0.08

Question 10

What is Winter’s formula–the formula for compensated p(CO2) in metabolic acidosis?

Answer 10

p(CO2) = 1.5[HCO3-] + 8 (+/- 2)

Question 11

Anion gap indicates the presence of ________.

Answer 11

additional acid

Question 12

What are substances that can cause anion gap?

Answer 12

MUD PILES (methanol, uremia, DKA [and other ketoacids], propylene glycol, INH, lactate, ethylene glycol, salicylates)

Question 13

Metabolic alkalosis is caused by _________.

Answer 13

excess bicarbonate

Question 14

The body will not hypoventilate to the point of hypoxemia, so compensation for _______ is incomplete.

Answer 14

metabolic alkalosis

Question 15

How can you differentiate acute and chronic forms of respiratory acidosis?

Answer 15

Chronic respiratory acidosis will have an increase in bicarb concentration.

Question 16

pKa =

Answer 16

• log (Ka)

Question 17

Intracellular buffers include _________; extracellular buffers include __________.

Answer 17

phosphates, hemoglobin, and proteins; phosphates, bicarbonate, albumin, and proteins

Question 18

Venous pH is only slightly lower than arterial pH because of __________.

Answer 18

hemoglobin

Question 19

The lungs adjust pH acutely by __________ and the _________ adjust pH chronically.

Answer 19

expelling CO2; kidneys (by retaining HCO3-)

Question 20

What are some central causes of chronic respiratory acidosis?

Answer 20

Obesity, neuromuscular disorders like ALS, hypothyroidism, and chronic lung diseases

Question 21

What are some acute causes of respiratory alkalosis? Chronic causes?

Answer 21

Acute = anxiety/panic, fever, mechanical ventilation, and pain. Chronic = pregnancy, salicylate toxicity, brain injury, living at high altitude.

Question 22

Non-anion gap metabolic acidosis is caused by ___________.

Answer 22

excess loss of bicarbonate, such as from GI or renal loss

Question 23

Some causes of metabolic alkalosis (in which bicarb levels are raised) are ________.

Answer 23

ingestion of bicarb; too much suction of gastric acid; diuretics; and hypovolemia

Question 24

Normal anion gap levels are ________.

Answer 24

10 - 14

Question 25

For chronic respiratory disturbances, a change in Pa(CO2) of 1 Torr should lead to a ___________.

Answer 25

a change of 0.4 mEq/L of bicarb in the same direction