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18 Cards in this Set
- Front
- Back
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What can acid base balance affect?
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Volume
Osmolarity pH (Hco3/H+) |
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What is the normal pH range of blood
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7.35-7.45
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What are the pathologies outside of these ranges called?
What effects do they have? |
Acidosis: Increase [K+] leading to arrhythmias and decrease hepatic funtion
Alkalosis: Lowers free Ca2+ leading to nerve excitability leading to tetany |
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What does plasma pH depend on?
What ratio? |
HCO3 : pCO2
20:1 |
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What affects pCO2?
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Ventilation Rate
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What controls [HCO3]
what can it be disturbed by? |
Kidneys
Renal disease and metabolic disorders |
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Name the two ways by which HCO3 in the blood can be increase
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1) reabsorption
2) creation |
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What are the two sources of HCO3 in the kidneys?
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Metabolism : CO2 + H20 = H+ and HCO3-
Amino acids: NH4+ + HCO3- |
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Other than Na-K-ATPase what transporter is involved in HCO3 reabsorption?
How does HCO3 get reabsorbed |
1) Na-H exchanger
2) H Out via exchanger; binds HCO3 to form CO2 and H20; they move into cell; Dissociate; H+ repeats and HCO3- moves out via basolateral membrane |
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When can HCO3 being coupled to Na reabsorption be a problem
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If a patient has alkalosis AND low volume eg vomiting
Body will put increasing volume ahead of alkalosis; so when Na is reabsorped to increase h20 reabsorption HCO will follow worsening the alkalosis |
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How does creation of HCO3 in DCT differ to the rest of the nephron
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Insufficient gradient of Na to drive Na-H exchanger so H+ ACTIVELY pumped out using ATP
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How is pH in urine prevented from becoming to low
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H+ is buffered by filtered PO4- and NH3
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What happens in PCT and DCT cells in response to acidosis?
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1) increase H+ ejection via exchanger in PCT
2) Increased ammonium production in PCT 3) Increased H+ATPase in DCT 4) Increased capacity to reabsorb HCO3 |
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What happens in Metabolic acidosis?
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-Decrease HCO3 because:
Metabolism produces other acids with other anions eg lactate. The other anion is metabolised elsewhere so the remaining H+ has to be soaked up by HCO3 lowering HCO in plasma |
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What is the anion gap
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It tells us the concentration of anions other than HCO- and Cl-
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How is it calculated?
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[K]+[Na]-[HCO3]+[Cl]
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What are it's normal ranges and what is it an indicator of
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10-15mmol/L
Metabolic Acidosis |
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What is the difference between correction and compensation
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Correction is when an acidosis or alkalosis resolved by a change in the original cause
Compensation is where they are corrected by a change in another process affecting acid-base status |
