Acid-Base Handling

Question 1

[H+] in extracellular fluid

Answer 1

35-45nmol/L

Question 2

pH range

Answer 2

7.35-7.46

Question 3

Determining pH

Answer 3

Log1/[H+]

Question 4

How is H+ excreted

Answer 4

Kidneys

Question 5

What produces H+ ions

Answer 5

Metabolism of proteins, carbohydrates and fats produce carbon dioxide, water and hydrogen ions

Question 6

What are the buffers in the body (5)

Answer 6

Bicarbonate (ECF, glomerular filtrate) 
Haemoglobin (RBCs)
Phosphate (renal tubular fluid, intracellular fluid)
Protein 
Bone

Question 7

What do buffers do

Answer 7

Mop up hydrogen ions

Question 8

What is the most important buffer in the body

Answer 8

Bicarbonate

Question 9

What is required to maintain homeostasis

Answer 9

Kidneys need to excrete hydrogen ions and regenerate bicarbonate

Question 10

How are bicarbonate ions regenerated

Answer 10

Using carbonic acid

Question 11

What transport system is used to excrete hydrogen ions in the kidney

Answer 11

Sodium transport system

Question 12

How is CO2 excreted

Answer 12

Lungs

Question 13

How is breathing controlled

Answer 13

Chemoreceptors in the hypothalamic respiratory centre

In health, any increase in CO2 stimulates respiration thus tending to maintain a stable concentration of CO2.

Question 14

Causes of metabolic acidosis (3)

Answer 14

Increased H+ production (DKA)
Decreased H+ excretion (renal tubular acidosis) 
Bicarbonate loss (intestinal fistula)

Question 15

High H+

Low HCO3

Answer 15

Metabolic acidosis

Question 16

High H+
Low HCO3
Low CO2

Answer 16

Compensated metabolic acidosis

Question 17

High H+
High HCO3
High CO2

Answer 17

Respiratory acidosis

Question 18

High H
Very High HOC3
High CO2

Answer 18

Chronic respiratory acidosis

Question 19

Causes of respiratory acidosis (3)

Answer 19

Decreased ventilation
Poor lung perfusion
Impaired gas exchange
e.g. pneumonia

Chronic respiratory acidosis - COPD

Question 20

Causes of metabolic alkalosis (4)

Answer 20

H+ loss (pyloric stenosis)
Hypokalaemia
Ingestion of bicarbonate
Anaerobic exercise

Question 21

Low H+

High HCO3

Answer 21

Metabolic alkalosis

Question 22

Low H+
High HCO3
High CO2

Answer 22

Compensated metabolic alkalosis

Question 23

Causes of respiratory alkalosis

Answer 23

Due to hyperventilation (voluntary, artificial ventilation, stimulation of respiratory centre)

e.g. Panic attack

Question 24

Low H+
Low HOC3
Low CO2

Answer 24

Chronic respiratory alkalosis

Question 25

What does H+/pH indicated

Answer 25

Overt acidosis/alkalosis

Question 26

What does pCO2 indicated

Answer 26

Respiratory disturbance (primary or secondary)

Question 27

What does pO2 indicate

Answer 27

Respiratory function and tissue oxygenation

Question 28

How are bicarbonate, pCO2 and pH interrelated

Answer 28

{H+} = k x pCO2/[HCO3-]