Gas Exchange Flashcards
Understand all the steps in O₂ delivery & CO2 removal
- ventilation (bulk flow): maximizes oxygen levels- air in and out of lungs
2.
Rate of flow depends on
Pressure differential- higher flow with greater difference
Viscosity- lower flow with higher viscosity (thickness)
- air is easier to move because H20 is more viscous
Diameter of tubes- larger = greater flow
Bulk flow
Movement of fluids (water and air) by generating a pressure difference
What influences the rate of diffusion of a gas?
Partial Pressure gradients - F=kA p1-p2/d
- Greater SA= Greater rate of diffusion
- Longer distance of diffusion = Lower rate of diffusion
Partial pressure and why is important to diffusion rates
It’s found in air, water, or hemoglobin
- Affected by solubility
Px=Ptotal x Fx
What is good at storing Oxygen and increases effective solubility
Hemoglobin
What is more soluble in water than oxygen?
CO2
Sea level pressure in torr
1 torr=1 mm Hg (pressure unit)
SEA LEVEL- 760 torr
AIR PO2- 160 torr
What does Px=Ptotal x Fx stand for?
P total- total pressure of the mixed gas
Fx- fraction of the gas mixture that is X (0.21 for oxygen)
How does ventilation in air compare to water?
Air
- high O2 content
- low density and viscosity
- more diffusible (O2>H2o)
- doesn’t absorb much heat
- respiratory system dry
Water
- low O2 content
- low density and viscosity
- less diffusible
- high specific heat
How do increased body size and metabolic rates affect O2 consumption relative to SA?
Greater body size- harder to get oxygen to all tissues
Higher metabolic rate- more oxygen
What are ways animals increase O2 delivery?
- more complex respiratory surfaces to increase SA
- more ventilation = increase PO2
- more circulation = decrease internal PO2
How do simple and complex gills differ?
Simple:
- increases SA for diffusion of oxygen
- ventilation is passive
Complex:
- Greatly increased SA
- active ventilation (one way flow)
- counter current exchange system
How does counter-current exchange increase O2 extraction from water?
Flow is in opposite direction to eachother
- diffusion adds oxy to blood, water is max maintaining gradient for diffusion
- concurrent: reaches equilibrium
Why do gills work well for water but not terrestrial conditions?
External- cheap to move water in one direction (flow through systems)
- no water loss
- rely on buoyancy of water (gravity)
Benefits to terrestrial enrvironments for respiratory systems
- reduces water loss rate
- air is cheaper/easier to move into internal spaces than water (tidal ventilation)
- internal structures are easier to support without water
How do insects exchange respiratory gases with the air?
Tracheal systems
- series of tubes (tracheae) that carry gases directly to and from tissues
- spiracles (opening of tracheae) can be closed to reduce water loss
How do vertebrates exchange respiratory gases with the air?
Lungs (tidal flow)
- SA
- positive pressure ventilation: push air from their mouth (amphibians)
- negative pressure ventilation: expand lungs, drop pressure in the lungs to pull air in