Flashcards in Session 5 - Acid-Base Balance Deck (12)
What is the normal range for plasma pH?
What is a plasma pH greater than 7.45 known as?
What is a plasma pH less than 7.35 known as?
How does alkalaemia increase neuronal excitability? What does it therefore lead to?
Alkalaemia lowers free calcium by causing Ca2+ ions to come out of solution. This therefore increases neuronal excitability and can lead to paraesthesia and tetany.
What effect does acidaemia have on plasma potassium ion concentration?
Acidaemia increases plasma potassium concentration (hyperkalaemia). This effects excitability, particularly of cardiac muscle, leading to arrhythmias.
What is the reaction in the CO2/HCO3- buffer system?
CO2 + H2O H+ + HCO3-
Plasma pH depends on what ratio?
Ratio of [HCO3-] to pCO2. More CO2 drives the reaction to produce H+, more HCO3- drives the reaction to remove H+.
What two organs work together to control plasma pH?
Lungs and kidneys
How do the kidneys control pH?
Variable recovery of bicarbonate and active secretion of hydrogen ions.
How to the lungs control pH?
Control of pCO2 and pO2.
Rate of ventilation controlled by chemoreceptors.
How does acidosis cause hyperkalaemia?
High concentration of H+ in blood.
Increase in movement of H+ into cells.
Therefore an increase in K+ movement out of cell (reciprocal cation shift).
Decreased potassium excretion in the distal nephron.