Home > Uncategorized > Respiratory Physiology Lecture 4 Notes: Acid Base Chemistry

Respiratory Physiology Lecture 4 Notes: Acid Base Chemistry


Today we’ll spend 43 minutes on the acid base chemistry of the lungs.



The lungs and the kidneys are the organs that control acid base status. 

Bronsted acids donate H+ in slution.  Baces accept H+.  A buffer is a substance that can reversib bind hydrogen ions. 

Blood Buffers

H+ + Pr = HPr

H+ + HPO4- = H2PO4

H+ + HCO3- = H2CO3

K = H+ HCO3-/H2CO3

pH = pK + log HCO3-/0.03 pCO3

The Henderson Hasselbach Equation

pH= 6.1 + log (24/]0.03 x 40])

pH = 7.4

The Davenport diagram shows plasma bicarbonate versus pH.  Bicarbonate is HCO3-.  The lower the bicarb concentration, the lower the pH

Respiratory acidosis- raise pCO2.  pH increases. 

Respiratory alkalosis – lower pCO2, lower pH. 

Metabolic acidosis – change in bicarbonate, lower.  pH decreases. 

Metabolic alkalosis –  an increase in bicarbonate levels. 

The O2 Transport System

Oxygen in from ventilation, diffusion, perusion, diffuison. 

Oxygen out by tissue, heart and circlatiion, lungs. 

Volume of gas = area/thickness x diffusivity x pressure difference

Diffusivity = solubility/sqrt MW

Mitochondria get upset when pO2 falls too much. 

hypoxic hypoxia at high heights.

anemic hypoxia comes from low O2 carry capatcity.

circulatory hypoxia is a general decreased in cicrulation.

histotoxic hypoxia is when a poison in the tissue prevent oxygen utilization.


Visible Light – 400 to 700 nm

Aromatic: planar, cyclic, Huckels Rule – 4n+2 electrons

Fibrous – sclera, cornea

Sensory – retina

Vascular – choroid, iris, pupil, ciliary body

Kingdoms – monera, protista, fungi, plant, animal

HSbF6 pKa = 25

Electrophiles are positive, nucleophiles are negative

EDTA is a tetraprotic acid.

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