Acid-Base Balance

Question 1

For the purposes of this class what is the definition of an acid and a strong acid?

Answer 1

Acids can donate a hydrogen ion; strong acids completely or nearly completely dissociate into a hydrogen ion and its conjugate base in aqueous solution

Question 2

What is a buffer?

Answer 2

A mixture of substances (usually a weak acid and its conjugate base) in aqueous solution, that can resist changes in hydrogen ion concentration when strong acids or bases are added

Question 3

How is pH calculated?

Answer 3

pH= -log [H+]

Question 4

What is the pH cutoff value for acidemia? alkalemia?

Answer 4

Acidema= pH 7.45

Question 5

What is the normal, healthy value of blood pH?

Answer 5

7.4

Question 6

How are volatile acids eliminated from the body? What are examples of volatile acids?

Answer 6

Eliminated by lungs- include glucose and fat

Question 7

How are fixed acids eliminated from the body? What are examples of fixed acids?

Answer 7

Eliminated by kidneys- include glucose, cysteine, and phosphoprotein

Question 8

What is the isohydric principle?

Answer 8

All buffer pairs in a homogenous solution are in equilibrium with the same hydrogen ion concentration

Question 9

What is the fastest buffer in blood?

Answer 9

Bicarbonate

Question 10

How does phosphate as a buffer?

Answer 10

It can take up and bind hydrogen

Question 11

How do bones act as buffers in chronic acidosis?

Answer 11

Ca++ is replaced with H+

Question 12

What is the effect of increased CO2 on blood pH and bicarbonate concentration?

Answer 12

Increased CO2 will decrease pH and the bicarbonate concentration will increase?

Question 13

Why does bicarbonate increase with increased CO2 levels in spite of decreasing pH?

Answer 13

Some H+ will be buffered by other non-bicarbonate buffers in the body, which frees up more bicarbonate

Question 14

How does increased hemoglobin affect bicarbonate levels at different pHs?

Answer 14

There will be increased bicarbonate at lower pHs because more H+ can bind to Hb

Question 15

What is the respiratory compensation for metabolic acidosis?

Answer 15

Increased H+ conc. stimulates chemoreceptors, which increase alveolar ventilation, decreasing CO2 and increasing pH

Question 16

What is the renal compensation for acidosis? For alkalosis?

Answer 16

Acidosis= increased fixed acid excretion and decreased bicarbonate excretion; alkalosis= decreased hydrogen ion excretion and increased bicarb excretion

Question 17

How is the anion gap calculated? What is the normal value?

Answer 17

Anion gap= [Na+]-([Cl-] + [HCO3-]); Normally 12 +/- 4 mEq/L

Question 18

What conditions could result in metabolic acidosis with an abnormally great anion gap?

Answer 18

Lactic acidosis, ketoacidosis; ingestion of organic acids like salicylate, methanol or ethylene glycol, or renal retention of anions such as sulfate, phosphate, and urate

Question 19

What are the different classifications of the causes of hypoxia?

Answer 19

Hypoxic hypoxia, V/Q mismatch, anemic hypoxia, hypoperfusion hypoxia, histotoxic hypoxia

Question 20

What is hypoxic hypoxia?

Answer 20

Conditions in which arterial PO2 is abnormally low

Question 21

What are some possible causes of hypoxic hypoxia?

Answer 21

Low alveolar PO2, Diffusion impairment, right to left shunts, V/Q mismatch

Question 22

What causes anemic hypoxia?

Answer 22

A decreased in the amount of functioning hemoglobin

Question 23

What is histotoxic hypoxia?

Answer 23

Poisoning of the cellular machinery that uses oxygen to produce machinery