Gas exchange in aquatic environments Flashcards
Why is the amount of oxygen in water different from the amount of oxygen in the air?
Water is more dense and more viscous, and lower oxygen solubility
What else will affect the amount of oxygen dissolved in water?
Temperature and dissolved salts
What are the 5 things that must be considered for respiratory anatomy to be effective?
Surface area, thickness of the respiratory surface, degree of vascularization, direct with external media, direction of media flow
Why does body size affect the respiratory needs of animals?
A larger animal has a lower surface area to volume ratio, and diffusion distance also increases
What is the relationship between time for diffusion and distance?
Time for diffusion increases with distance squared
What happens to the surface area to volume ratio if the radius increases?
Decreases
When is cutaneous respiration effective?
When the skin is small, thin, and moist
How are metabolic rate and oxygen consumption related?
Higher metabolic rate = higher oxygen demand
What would be the advantage of having thicker respiratory membranes if it reduces diffusion?
Reduces water loss in organisms like lower metabolic needs
What is ventilation?
Movement of environmental medium over the respiratory surface
What are the 3 types of respiratory systems?
Lungs, internal gills, and external gills
What are lungs?
An invagination into the body
What are internal gills?
An evagination out into a smaller body cavity protected by a flap of skin
What are external gills?
An evagination directly out into the medium
What are the 3 types of ventilation?
Non-directional, tidal, unidirectional
What type of respiratory system uses non-directional ventilation?
External gills
What is non-directional ventilation?
The medium comes into contact with the respiratory surface in many directions
How does medium mixing affect the efficiency of respiration with external gills?
Lower efficiency when there is poor mixing and a boundary layer
What is tidal ventilation?
Air or water flows to and from the respiratory surface through the same passage
Do lungs empty between breaths?
No, there is always some still in there that the new air will mix with
How do the internal partial pressure between the blood and medium compare in tidal ventilation?
Partial pressure in the blood is lower than in the ambient air
What is unidirectional ventilation?
Air comes across the respiratory surface in one direction
What are the 3 types of unidirectional ventilation?
Concurrent, countercurrent, cross-current
What is concurrent ventilation?
Blood and medium flow in the same direction
What is counter current ventilation?
Blood and medium flow in opposite direction
What is cross current ventilation?
Blood flows at an angle to the medium
What form of unidirectional ventilation is the best?
Countercurrent > cross current > concurrent
