19/03/19
Dr Rachel O’Callaghan
Respiratory Physiology
Partial Pressures
Air =
• 78% nitrogen
• 21% oxygen
• 0.9% argon
• 0.03% carbon dioxide
Dalton’s Law
• In a gas mixture, each has a partial pressure
• Sum of these partial pressures gives the total pressure for the gas
• Partial pressure of a gas is proportional to the number of gas molecules
o Pressure x percentage of gas
High Altitude
• As altitude increases, atmospheric pressure decreases
o Air becomes thinner
o At the top of Everest, air has 1/3 O2 content per unit volume
• Atmospheric pressure = pressure exerted on something on the face of the earth
• Humans need supplemental oxygen to survive above 4000m
• Many other animals climb high with no effects
o E.g. pikas and jumping spiders
Adaptations
• Able to extract O2 more efficiently from air
• Tolerate low blood O2
• Tolerate changes in blood CO2 and pH
Cellular and External Respiration
• Cellular – process where mitochondria consume O2 and produce CO2 and ATP
• External – exchange of O2 and CO2 between external environment and mitochondria
Diffusion and Bulk Flow
• Mitochondria lower local O2 concentration
o Concentration gradient – low in cell and high in blood
• Unicellular and small aquatic organisms use diffusion gradients
• Large animals use diffusion and bulk flow
o Diffusion – short distances
o Bulk flow – long distances
Dr Rachel O’Callaghan
Respiratory Physiology
Partial Pressures
Air =
• 78% nitrogen
• 21% oxygen
• 0.9% argon
• 0.03% carbon dioxide
Dalton’s Law
• In a gas mixture, each has a partial pressure
• Sum of these partial pressures gives the total pressure for the gas
• Partial pressure of a gas is proportional to the number of gas molecules
o Pressure x percentage of gas
High Altitude
• As altitude increases, atmospheric pressure decreases
o Air becomes thinner
o At the top of Everest, air has 1/3 O2 content per unit volume
• Atmospheric pressure = pressure exerted on something on the face of the earth
• Humans need supplemental oxygen to survive above 4000m
• Many other animals climb high with no effects
o E.g. pikas and jumping spiders
Adaptations
• Able to extract O2 more efficiently from air
• Tolerate low blood O2
• Tolerate changes in blood CO2 and pH
Cellular and External Respiration
• Cellular – process where mitochondria consume O2 and produce CO2 and ATP
• External – exchange of O2 and CO2 between external environment and mitochondria
Diffusion and Bulk Flow
• Mitochondria lower local O2 concentration
o Concentration gradient – low in cell and high in blood
• Unicellular and small aquatic organisms use diffusion gradients
• Large animals use diffusion and bulk flow
o Diffusion – short distances
o Bulk flow – long distances
