Respiration Flashcards
Cell respiration
In the cell, O2 + Sugar -> Energy + CO2 + H2O
External Resp
Gas exchange with environment, in and out of cells and in and out of the body
Two basic steps in gas exchange (External Respiration)
Passage of O2/CO2 through a respiratory membrane
Transport of O2/CO2 between respiratory membrane and the cells of the body via some method of dispersal
How do respiratory gases transport across the plasma membrane?
Respiratory gases (O2 and CO2) diffuse easily through the lipid bilayer (simple diffusion) since they are so small
Cutaneous Respiration
Where?
What Conditions?
Skin serves as respiratory membrane
Found in some aquatic and terrestrial animals
3 conditions needed:
Very small body size (less than 1 mm in diameter)
High SA: Volume ratio (mass)
Very low metabolic rate
Explain how body size matters relative to cutaneous respiration
As body size increases, volume of cells increases much more rapidly than surface area (where diffusion occurs), thus making it inefficient to oxygenate cells solely with this process
Volume = L ^3
SA = L^2
SA : Volume ratio
Smaller things have higher surface area to volume ratios
Animals that rely solely on cutaneous respiration
Sponges (aquatic) ,
Hydras (aquatic),
Flatworms (aquatic or terrestrial),
Earthworms (aquatic or terrestrial),
Plethodontid salamanders (primarily terrestrial) (can get large but have low metabolic demand)
Hellbender Amphibian unique because…
Example of how many amphibians have respiratory organs, but still rely extensively on cutaneous respiration
30-74 cm
FEATURES THAT INCREASE SA FOR CUTANEOUS RESPIRATION
body and head are dorsoventrally flattened
skin is loose and wrinkled
however, they also have lungs
Respiratory organs have…
Respiratory membranes that are localized
An increased surface area to maximize their gas exchange potential
(Gills and Lungs are examples of respiratory organs)
Air vs. Water properties in terms of gases
79% Nitrogen, 21% oxygen (.04% CO2)
Fast diffusion
Water: generally 1% oxygen or less, diffusion slow
Comparatively, air has 20x more oxygen than water
Comparatively, gas molecules diffuse 10,000x more faster in air than in water
2 types of gills… in…
External Gills - in larval salamanders, many invertebrates
Internal gills - in fishes, molluscs, arthropods
Tadpoles and bony fish have…
Internal gills
Respiratory membranes in fish are composed of…
Long sections called gill fillaments
On the gill filaments exists lamella(e) that are perpendicular to the direction of gill filaments
Bony fish Gills use…
Countercurrent exchange-
Water flows across the lamellae in opposite directions relative to blood within the respiratory membrane
This process works because concentration of O2 is paralleled by the blood flow through the lamellae, allowing oxygen to go down its concentration gradient
Countercurrent exchange
Systems do not reach equilibrium and exchange takes place over the entire length
More O2 is exchanged (relative to concurrent)
Concurrent exchange
Systems reach equilibrium and no further oxygen takes place at the theoretical half-way point because oxygen will no longer be able to go down its concentration gradient past 50%
Ventilation
Movement of respiratory medium (air or water) over the respiratory membrane (alveoli, lamellae, etc)
Lungs and tracheal systems must also be ventilated