Lecture 13: CO2 Transport And pH Balance Flashcards
What is the arterial PCO2?
40 mmHg
What is the venous PCO2?
45 mmHg
How is CO2 transported?
- 5% dissolved (20x more soluble than O2)
- 5% carbaminohaemoglobin (binds to terminal NH2 so doesn’t compete with O2)
- 90% HCO3
What is the haldane effect?
If PO2 decreases in the blood it will increase binding of O2 to Hb, binding of O2 causes CO2 to be kicked off
What factors affect total blood CO2?
PCO2 PO2 [plasma proteins] [Hb] Plasma pH
What is the pKa of H2CO3?
6.1
What is the ECF concentration of H+ and pH?
[H+] = 40nEq/L pH = 7.4
How does increased metabolic activity increased [H+]? How much is produced and ingested?
CO2 production
Inorganic acid production during nutrient breakdown
Organic acids made during intermediary metabolism
80mEq/l/day is produced and ingested
Acidosis causes the kidneys to secret more _________ and less ______ than normal
H+
K+
Decreases in pH –> ____________ in serums K which makes cells ________ excitable by causing __________.
Increases serum K+
Hyperkalaemia makes cells more excitable by depolarising them
Can cause arrhythmia
Acidosis causes CNS ____________, Alkalosis causes ____________ of the NS
Depression
Hyperexcitability
What helps buffer the pH in the body?
Bicarbonate buffer
H2PO4-/HPO4 2- buffer
Proteins buffer up to 60-70%
How does the respiratory system respond to a change in pH?
- minutes to hours
- increase pH = decrease in ventilation
- decrease pH = increase in ventilation
How do the kidneys respond to a change in pH?
- hours to days
- increase pH = increase HCO3 secretion, increase H+ absorption
- decrease pH = increase HCO3 absorption, increase H+ secretion
Respiratory acidosis/alkalosis is primarily caused by __________
Δ PCO2
