L38 - Acid Base Balance (resp)

Question 1

What does arterial blood ph range from> intracellular?

Answer 1

• 7.36-7.44
• ~7.2

Question 2

What is the most important buffer?

Answer 2

HCO3-/CO2 system (bicarbonate system)

Question 3

What does carbonic anhydrase do in the body?

Answer 3

• catalyse conversion of CO2 + H2O to H2CO3
• H2CO3 (v unstable) -> HCO3- + H+
• (in equilibirum)

Question 4

What controls regulation of CO2?

Answer 4

• chemoreceptors and lungs
• regulation by ventilation

Question 5

What controls regulation of HCO3- and H+?

Answer 5

• kidneys
• HCO3- filtering or generation of H+ secretion

Question 6

What is carbony anhydrase (CA)?

Answer 6

• zinc metalloenzymes
• expressed in tissues (lungs, kidney, eyes, intestines and RBC
• cytosolic and membrane located isoforms of CA
• plants and corals can also express

Question 7

What is the eqn to calculate pH (with CO2 and HCO3-)?

Answer 7

pH = 6.1 + log(HCO3-/00.3 x PCO2)

Question 8

What are the steps of transport of CO2 from tissues?

Answer 8

• CO2 generated by tissues
• 10% CO2 dissolves in plasma and RBC
• 25-30% reacts with Hb to form HbCO2 (carbaminohemoglobin)
• 60-65% converted by CA to HCO3- and H+
• chloride shift - electroneutral exchange of HCO3- for Cl- ions

Question 9

What are the steps of CO2 to lungs?

Answer 9

• loss of CO2 leads to HCO3- to combine with H+ to generate CO2
• loss of CO2 leads to dissociation of Hb to release CO2
• expired CO2

Question 10

Why is net diffusion of CO2 into alveolus?

Answer 10

Blood CO2 > alveolar CO2
= net diffusion of CO2 into alveolus

Question 11

What is the transport of hydrogen ions between tissues and lungs?

Answer 11

• blood flows through lungs and reaction is reversed
• deoxyhemoglobin binds to O2 to form oxyhaemoglobin HbO2