07 CO2 - Boards and Beyond

  • CO2 stored as HCO3 to be transported to lungs

Bohr Effect

  • conversion produces H+ ion that binds to globin chain to form HHb

  • instead of dropping from 100 to 75% at tissue PO2 50 mmHg, drop to 50%, better unloading
  • Bohr effect helps unload O2 via H ion binding to Hb

Cl Shift

  • high bicarb inside cell diffuse out, in exchange for Cl

Haldane

  • x: level of CO2
  • y: amount CO2 bound to Hb
  • purple line: normally, more PCO2 in blood = more bound to Hb
  • in reality, blue line: even more bound to Hb at low O2 level

  • Bohr for O2

High Altitude

  • small box: someone living at high altitude

  • mild polycythemia

Exercise

  • arterial side maintain normal rate: not hypoxic or hypercapnea

Cerebral blood flow

  • cerebral vasodilator
  • left, O2: at normal range, O2 does not change cerebral blood flow much
  • right, CO2: at normal range, powerful effect on blood flow

Breathing

  • CO2 in blood stream major stimulus, not O2
  • PNS chemoreceptor: only kick in under severe hypoxia, normally CNS working

  • hypoxemia stimulate respiratory rate, can get low with O2 = high CO2, confusion

  • in hospital on ventilation, O2 can make O2 saturation high and mask hypoventilation
  • put on ventilator

  • hypo ventilating, CNS symptoms