Anatomy & Anatomy & Physiology IIPhysiology II

Unit SixUnit Six

Major Atmospheric Major Atmospheric GasesGases

Nitrogen - NNitrogen - N22 - 78% - 78%

Oxygen - OOxygen - O22 - 21% - 21%

Carbon dioxide - COCarbon dioxide - CO22 - 0.04% - 0.04%

Dalton’s LawDalton’s Law

The total pressure of a gas The total pressure of a gas mixture is the sum of the mixture is the sum of the partial pressures that each of partial pressures that each of the gases in the mixture the gases in the mixture would exert independentlywould exert independently

RespirationRespiration

Respiration is divided into Respiration is divided into three phases:three phases: + ventilation+ ventilation + external respiration+ external respiration + internal respiration+ internal respiration

Blood Gas TransportationBlood Gas Transportation

Oxygen transport:Oxygen transport: * hemoglobin on RBCs - * hemoglobin on RBCs - 98.5%98.5% * dissolved in plasma - 1.5%* dissolved in plasma - 1.5%Carbon dioxide transport:Carbon dioxide transport: * hemoglobin on RBCs - 20%* hemoglobin on RBCs - 20% * dissolved in plasma - 10%* dissolved in plasma - 10% * converted to HCO* converted to HCO33

-- - 70% - 70%

HHb + OHHb + O22 HbO HbO2 2 + H+ H++

Formation of oxyhemoglobinFormation of oxyhemoglobin

COCO2 2 + Hb HbCO+ Hb HbCO22

Carbaminohemoglobin Carbaminohemoglobin formationformation

The Oxyhemoglobin The Oxyhemoglobin Dissociation CurveDissociation Curve

Oxyhemoglobin and Oxyhemoglobin and the Unloading Oxygenthe Unloading Oxygen

pH and temperature will affect the pH and temperature will affect the rate and amount of HbOrate and amount of HbO22

dissociationdissociation

The Bohr effect - the increase in The Bohr effect - the increase in HbOHbO22 dissociation in response to dissociation in response to

low pHlow pH

Oxyhemoglobin and Oxyhemoglobin and the Unloading Oxygenthe Unloading Oxygen

The decrease in pH is the result of The decrease in pH is the result of glucose metabolism in cellsglucose metabolism in cells

The metabolism results in HThe metabolism results in H++ and and COCO22 being passed into the being passed into the

capillaries, decreasing the pH and capillaries, decreasing the pH and increasing the Pcoincreasing the Pco22

Oxyhemoglobin and Oxyhemoglobin and the Unloading Oxygenthe Unloading Oxygen

HbOHbO22 is induced to give off O is induced to give off O22 for for

four reasons:four reasons: ► ► ambient Poambient Po22

► ► temperature increasetemperature increase ► ► pH decreasepH decrease ► ► BPG (biphosphoglycerate)BPG (biphosphoglycerate)

The Effects of The Effects of Temperature Temperature

and pHand pH

The The OxyhemoglobiOxyhemoglobi

n n Dissociation Dissociation

CurveCurve

Neural Neural Control of Control of

RespirationRespiration

Pontine Pontine respiratory respiratory

centercenter

Dorsal Dorsal respiratory respiratory

groupgroupVentral Ventral respiratory respiratory

groupgroup

Neural Control of Neural Control of RespirationRespiration

Neural Neural Control of Control of RespiratioRespiratio

nn

Neural Control of Neural Control of RespirationRespiration

Since OSince O22 is carried in such high is carried in such high reserves and saturation, it has reserves and saturation, it has little effect on the rate of little effect on the rate of ventilationventilationCOCO22 concentration and pH do concentration and pH do significantly change and have significantly change and have an immediate effect on an immediate effect on ventilationventilation

Neural Control of Neural Control of RespirationRespiration

Therefore, ventilation functions Therefore, ventilation functions to maintain Pcoto maintain Pco2 2 within its within its homeostatic rangehomeostatic range