Homeostasis by the kidney- Acid-Base balance Flashcards
What are the 2 mechanism of dealing with the acid load in the body
Buffering
Elimination
What is used in mechanisms of buffering when dealing with acid load in the body
Bicarbonate in Extracellular Fluid (ECF)
HPO42- in Intracellular Fluid (ICF)
CO3 2- in Bones
How is the acid load in the body dealt with through elimination
Increased respiratory drive to increase CO2 excretion
Acute response
Increased hydrogen ion secretion by kidneys
Chronic sustained response
What is the acute response of the body to acid load
increased respiratory drive to increase CO2 excretion
What is the chronic sustained response to acid load
increased hydrogen ion secretion by the kidneys.
Homeostasis maintains the pH of the ECF between
7.35 - 7.45
plasma ph level below 7.35 is _____
acidosis
plasma levels rise above 7.45 is __
Alkalosis
Alterations outside these normal plasma pH range affects all body systems and result in
coma, cardiac failure and circulatory collapse
What does Henderson-Hasselbalch Equation explain in acid base balance?
Inverse relationship between pH and plasma concentration of CO2 i.e. when one goes up the other goes down and vice versa. So when pCO2 increases, e.g. in COPD, pH decreases (acidosis) as CO2 reacts with water to form carbonic a
What are the 2 main sources of acid generations in the body
carbolic (volatile) acids
Non-Carbolic (non-volatile) Acids
What are the sources of carbolic acids in the body
Generated from metabolism of carbohydrates and fats
Produced as CO2 and converted to H+ and HCO3-
Reconverted back to CO2 and eliminated by the lungs through loss of CO2
What the sources of non-carbolic (non-volatile) acids in the body
Generated from metabolism of sulphur containing amino acids
Buffered with HCO3- before eliminated by the kidneys through loss of H
What is the normal range of urine PH
4.6 - 8
What is the normal range of blood pCO2
4.7 - 6.0
What is the normal ranges of blood HCO3-
22 - 26 mmol/L
What are main sites of nephron where acid is excreted
proximal convoluted tubule and the intercalated cells of cortical collecting ducts
The kidney has limited acid secretions in form of
H+