BI256 Lecture Notes - Lecture 21: Hexapoda, Gas Exchange, Trachea
Document Summary
Animals mar 1st /16 hexapoda part 2 - anthropoda iv: chapter 21. Efficient respiratory transport systems required, permitting gas exchange but restricting water loss. Tracheal system: extensive network of thin walled tubes that branch into every part of the body. Spiracle: valve opening to the tracheal system sieve plate to prevent entry water, etc. Trachea branch out into tracheoles which branch into fine network over cells. Small insects: gas transport occurs entirley by a diffusion gradient, o2 consumption in tracheal system creates a partial vacuum which draws air in. Large insects: muscualr moveemnts of abdomen pumps air through system. Aquatic insects: spiracels are usually non-functional, an air bubble can be held over the surface by secreted wax and hairs. In some larval insects, tracheal or rectal gill may be present. Circulation is with a tubular heart in the pericardial cavity moving hemolymph forward through dorsal aorta via a peristalitic wave.
