Gas Exchange Flashcards
(47 cards)
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
What is the structure of the mammalian respiratory system, and how does it work?
Mammalian lungs exchange gas with blood at alveoli
- series of branching tubes: trachea -> bronchi -> bronchioles -> alveoli
- short diffusion
- large SA
How is ventilation carried out in Mammalian Lungs
Mammalian lungs have high elasticity
- expand thoracic cavity -> drops pressure surrounding lungs -> expands lungs -> alveoli expands -> drops the pressure
What is the structure of the avian respiratory system and how does it work?
Flow through lungs- air entered through the back and go out through the front BUT dont expand
- air sacs expand but do not exchange gases
- gas exchange occurs at parabronchi
How is ventilation carried out in flow through lungs
- air gets drawn in, posterior, air sac expands, thoracic cavity is contracting, air sacs are compressed, air is forced out through the lungs
- Air sac expands, pulls air in from lungs
- exhaled from the anterior air sac out through the mouth
Circulatory system consists of..
Blood vessels, a heart to generate hydrostatic pressure, blood (hemolymph) that moves through vessels
What are the functions of blood in addition to gas transport?
Move gases, move nutrients/waste, distribute hormones/immune system cells, distribute heat, provide hydrostatic pressure