BIOL126 Lecture Notes - Lecture 6: Respiratory Alkalosis, Hypercapnia, Hypocapnia
8 Jun 2018
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Acid base balance
• Describe the relationship between hydrogen ions, bicarbonate ions, carbon dioxide and
water
o Hydrogen ion concentration
• Plasma/ECF pH is narrowly limited to a range of 7.35-7.45
• Narrow vital range: 6.8-7.7
• Change in H+ concentration is normal due to metabolism
▪ Homeostasis serves to maintain physiological pH
• Abnormal states
▪ Acidosis = pH of blood below 7.35 (more common)
▪ Alkalosis = pH of blood above 7.45
▪ Affects membrane stability, enzyme activity, plasma protein stability,
BP, muscle contraction, CNS
o Acid
• Any dissolved substance that can donate H+ ions
• Sources
▪ Volatile acid n=1 Carbonic acid
• Can leave solution by converting to CO2 and enter the atmosphere
at lungs
• CO2 + H2O = H2CO3
• Spontaneously forms from water and CO2
• Process increased by carbonic anhydrase present in many cells
e.g. RBCs, liver and kidney cells
• CO2 from tissue is usually converted to H2CO3 which then
dissociates to H+ + HCO3-
• Formation of bicarbonate and carbonic acid is reversible
• In lungs, bicarbonate re-enters RBC, recombines with H+ to form
CO2 + H2O
▪ Metabolic acids n=many
• All acids produced in body from sources other than CO2 (not
excretedby the lungs - not volatile)
• Accumulate in solution until excreted by kidneys, or don't
accumulate and are further used in the body
• e.g. incomplete metabolism of carbohydrates, fats and
proteins
• Examples include lactic acid, acetyl CoA, phosphoric acid,
sulfuric acid, keto acids (ketones), amino acids
o Sources of hydrogen ion: gain
• Generation from CO2
find more resources at oneclass.com
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Document Summary
Bp, muscle contraction, cns: acid, any dissolved substance that can donate h+ ions. Sources: volatile acid n=1 carbonic acid, can leave solution by converting to co2 and enter the atmosphere at lungs, co2 + h2o = h2co3, process increased by carbonic anhydrase present in many cells. Spontaneously forms from water and co2 e. g. rbcs, liver and kidney cells: co2 from tissue is usually converted to h2co3 which then dissociates to h+ + hco3. Formation of bicarbonate and carbonic acid is reversible. In lungs, bicarbonate re-enters rbc, recombines with h+ to form. Loss of bicarbonate ions in urine: source of hydrogen ions: loss, base. Ingestion: breakdown of ingested products release of acidic or basic compounds, 60% alkaline foods and 40% acidic foods ideal. Fruit release acid when processed: excess h, metabolic acidosis, respiratory acidosis (increase in co2, deficit h, metabolic alkalosis, respiratory alkalosis (drop in co2, acidosis symptoms, decreased cns activity presenting as lethargy, coma and death, alkalosis symptoms.
