Internal Structures of Insects
Circulatory system: open; long dorsal vessel = heart pumps blood into head region; blood flows through spaces between organs to abdomen, re-enters heart through valves in posterior end
Nervous system: ventral double-string with largely autonomous ganglia; 3 ganglia fused to brain in head; brain is predominantly inhibitory (in contrast to stimulatory brains in vertebrates) ? feeding, moving, or copulating can continue without head
Respiratory system: no major respiratory organ; tracheae = hollow tubes with openings on body side branch into tracheoles, which carry oxygen (air) close to organs