Chapter 48, Problem 2Q

Summary Introduction

To analyze:

The reason for rise in the PO₂ (partial pressure of the oxygen) inside the tracheae when the spiracle is open, and then decrease in the pressure over time. Also, to review the effect of the fluttering of the spiracles on PO₂ ?

Given:

Researchers inserted the microscopic plastic tubes into the tracheae of the pupal stages of Attacus atlas moths in order to study tracheal function in the moths. They attached the microtubes to the sensors which helped them in recording the rate of CO₂ (carbon dioxide) that was released from the tracheae and also the intratracheal concentrations of O₂.

Pupae were placed in the chambers where normal atmospheric levels of the gases were maintained. Researchers then recorded the behavior of the spiracles, the rate of CO₂ release, and the O₂ concentrations in the tracheae. The results are shown in the figure A.

In order to examine the performance of the spiracles in the different atmospheric conditions and their effects on the rate of CO₂ release and O₂ concentrations, pupae were exposed to the different levels of atmospheric O₂. The levels of the release of CO₂ and O₂ concentrations were calculated during the fluttering stage as shown in the figure B.

Introduction:

The air in the body of the insects is exchanged via tracheae that have branches in the body and help in the O₂ and CO₂ in and out of tissues. They have spiracles that can exist in three phases. They can remain open, close, or flutter.