Images courtesy of: Wikimedia Commons

What is the primary mechanism for gas exchange?

Image courtesy of: Wikimedia Commons

The lungs seem to be the primary mechanism for gas exchange, but blood oxygen levels indicate that blood uptake of oxygen plays an intergal role as well. "Sensitivity to both decreased inspired oxygen and increased inspired carbon dioxide provides the basis for the chemical control of breathing" (Jackson, 1985). During activity, oxygen delivery must have an efficent dispersal to the active tissues. It is noted that the lung boasts a considerable gas distribution system. "In the turtle, the primary bronchus proceeds through the lung as a central air duct that gives rise to lateral channels, each channel supplying a separate, septated air space" (Jackson, 1985). Since the lung is multicameral, it houses air sacs, which acts as gas exchange units. Thus, the sea turtle is able to "exchange a large volume of lung gas very rapidly when it emerges to breathe" (Tenney, 1974). Moreover, these same mechanisms that are responsible for normal breathing patterns, also are responsible for the "nearly complete lung collapse when green turtles are exposed to large hydrostatic pressures (Berkson, 1967). Thus, green sea turtles house an elaborate system that displays the function of gas exchange, lung ventilation, and oxygen uptake simultaneously, without tampering with the physical behavior of the turtle.

 

How does gas exchange function during embryonic growth?

Images courtesy of: Pacific Regional Islands Office-NOAA National Marine Fisheries Service and Wikimedia Commons

 

By using the study of Ralph A. Ackerman on "Growth and Gas exchange of Embryonic Sea Turtles," it is observed that "when groups of eggs are incubated in artificial nests where gas exchange can be manipulated, rates of growth and hatching success are related to nest gas exchange" (Ackerman, 1981). In other words, successful growth of hatchlings is dependent upon the gas exchange in the nest. Several articles have alluded to gas exchange among a clutch in a nest arising from diffusion. Prange and Ackerman described diffusion occuring, "between the developing eggs in the green turtle nest and the air above the sand in which they are buried" (Prange, 1974). Similarly, Ackerman expresses the correlation between embryonic growth and gas exchange as a conductance, which influences the growth success of the hatchlings. "When sea turtle egss are incubated in artificial nests where the nest gas conductance produces a respiratory environment similar to that seen in natural nests (Ackerman, 1977), embryonic growth patterns and incubation time are similar to those in natural nests" (Ackerman, 1981).

 

 

 

 

This project was created as a part of a class project in the Animal Physiology class in the Department of Biology at Davidson College

E-mail questions to: snreid@davidson.edu

 

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