2012
2006
Diffusion
Convection
Water and Solute Regulation
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Water
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major fraction of body weight
cellular reactions take place in
transport of oxygen and nutrients
remove wastes
reactant in many cellular reactions (e.g. hydrolysis)
dehydration causes major problems
Salt balance also is important.
• ions such as K+ Ca2+ Mg2+, etc. must be kept within certain bounds.
• Imbalance of ion concentrations lead to disrupted cell function or cell death.
Systems that regulate water balance also affect concentrations of electrolytes.
Water moves from compartment to compartment by osmosis.
Solutes move by other membrane transport mechanisms
• Facilitated diffusion
• Active transport
Oxygen Solubility
•  Water severely limits oxygen solubility
•  Animals Evolve:
–  Respiratory Structures
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Lungs
Gills
Skin
Air-breathing organs
–  Mouth, guts, gas bladder, etc.
–  Circulatory System
•  Environment dictates the types of adaptations
Will Discuss Dead Zone vs Oxygen Minimum Zone Later
Oxygen Consumption
•  Cardiac output x arterial-venous differences
•  Cardiac output: heart rate x stroke volume
•  Arterial-venous differences
–  Dependant on activity state
–  Properties of the blood
Gas Delivery
•  Diffusion through the ectoderm
–  Cell surface as the exchange site
–  Limits the size of the organism
•  Open circulatory system
–  Mollusk and arthropods
–  Blood in hemocoel
–  Sluggish flow
•  Closed circulatory system
–  Blood contained within the vessels
–  Pigments in the blood
•  Myoglobin in hagfish
•  Hemoglobin for the rest
–  Active flow
Blood Circulation
•  To deliver
–  Nutrients
–  Oxygen
–  Hormones
•  To remove
–  Metabolic waste
–  Pathogens
•  Oxygen
–  Carbon dioxide
–  Hydronium ions
–  Temperature
–  Organic phosphate
No circulatory system to open
and closed system
Temperature
Terminology
•  Gas Content : mL/L
•  Partial Pressure: torr