Blood Acid-Base Balance

Question 1

What is a buffer?

Answer 1

Salts and weak acids that prevent major changes in pH

Question 2

What is an intracellular buffering?

Answer 2

Proteins and organic phosphates that act as buffers

Question 3

What is the Henderson-Hasselbach equation?

Answer 3

pH=pK + log [[HCO3-]/[PCO2 x 0.03]]

Question 4

What is pK?

Answer 4

6.1

Question 5

What is arterial HCO3 at rest?

Answer 5

24mMol

Question 6

What is arterial PCO2 at rest?

Answer 6

40mmHg

Question 7

What does the Davenport Diagram show us?

Answer 7

The relationship between pH, PCO2, and HCO3

Question 8

What is the blood buffer line?

Answer 8

Index of buffer capacity of the blood. This is a function of hemoglobin concentration because it uses up the H+ ions

Question 9

What can cause metabolic acidosis?

Answer 9

An increase in H+ ions from lactic acid that lowers the pH of the blood

Question 10

What does the body do to compensate for metabolic acidosis?

Answer 10

The decrease in pH stimulates the carotid body which stimulates an increase in breathing (hyperventilation) The increased breathing lowers the PCO2 and tries to raise the pH

Question 11

What buffers lactic acid?

Answer 11

HCO3. An increase in lactate leads to an equal decrease in HCO3

Question 12

What causes respiratory alkalosis?

Answer 12

Hyperventilation, ie at altitude

Question 13

What does the body do to compensate for respiratory alkalosis?

Answer 13

At elevation the lower inspired O2 lowers the PaO2 and a decreased PaCO2 due to the hyperventilation. this lowers the pH. The kidneys then start to retain H+ and dump HCO3. This lowers the bodies ability to buffer lactic acid

Question 14

Why do you blow into a paper bag when you are hyperventilating?

Answer 14

You are trying to increase the CO2 you are breathing out because too low of PCO2 can affect blood flow to the brain

Question 15

What can cause respiratory acidosis?

Answer 15

Hypoventilation or chronic lung disease

Question 16

What does the body do to compensate for respiratory acidosis?

Answer 16

Hypoventilation cause the increase PaCO2 and decrease the pH. The kidneys then start to retain HCO3 to prevent too low of a pH. If it is acute HCO3 is only elevated in small amounts. Chronic cases however have a very elevated HCO3

Question 17

What can cause metabolic alkalosis?

Answer 17

Vomiting or a loss of acid

Question 18

What does the body do to compensate for metabolic alkalosis?

Answer 18

The pH is increased which is sensed by carotid (peripheral and central) chemoreceptors. This stimulates hypoventilation. This will then raise the PaCO2 and lower the pH