Acid-base balance Flashcards
How does the respiratory system produce acid?
Carbonic acid from CO2
How is acid produced metabolically?
Organic acid (lactic, amino, hydroxybutyric) and inorganic (sulphuric, phosphoric)
How does the respiratory system remove acid?
Ventilation removes CO2
How is acid removed metabolically?
Inorganic acids (excreted by kidneys unchanged) and organic acids (undergo liver metabolism)
pH
- pH = -log10[H+]
- Acid-base homeostasis aims to keep pH constant
- Buffers act immediately
- Respiratory acts rapidly (minutes to hours) - normally self-regulated
- Renal is slow (hours to days)
pH buffers
- Proteins: albumins (ECF) and haemoglobin (ICF)
- Phosphate (ICF): HPO42- + H+ < = > H2PO4-
- Carbonic acid/bicarbonate system in ECF
What is the main ECF buffer?
Carbonic acid/bicarbonate
Henderson-Hasselbalch equation
pH = pKa + Log (HCO3- / H2CO3)
Equation for carbonic acid/bicarbonate buffer
H2O + CO2 = H2CO3 = H+ + HCO3-
What does PCO2 represent?
Respiratory component of acid-base balance
How does the renal buffer change pH
Alters H+ absorption
Function of intercalated cells
Determine final urine acidity in DCT
What is acidosis?
Impaired acid excretion
How is sodium reabsorbed?
H2CO3 dissociates to form H+ ions
Na+/H+ anti porter moved H+ out of tubular cell and Na+ in
Co-transport mechanism moves Na+ and HCO3- into interstitial fluid
+ve BE
Metabolic alkalosis