The digestive system mainly consists of the foregut, midgut and hindgut. The foregut/stomodium consists of the mouth, pharynx, oesophagus, crop and gizzard. The mouth is situated anteriorly below the labrum and between the mandibles. It leads into the buccal cavity. The hypopharynx lies on the floor of the buccal cavity. The salivary receptacujar duct opens behind the tongue.
Pharynx is narrow tubular part from where the oesophagus arises. The oeophagus is narrow and connects the buccal cavity to the crop. Crop is thin-walled sac, present in the whole of the thorax and serves as a reservoir for food storage. The midgut/mesenteron is a short narrow tube lined by glandular epithelium. It is the main organ of digestion and absorption. At the junction of gizzard and midgut 6 – 8 short fingerlike hollow tubes arise called hepatic caecae.
The hindgut/proctodaeum is a long tube like structure with 60 – 70 narrow thread like yellow structures called Malpighian tubules. The hindgut is differentiated into an anterior short, narrow ileum, middle long wide coiled colon and a terminal short dilated sac like structure the rectum which opens to the exterior by anus.
The nervous system of cockroach consists of the central and periphernal systems, The central nervous system is made of ganglia and nerve, cords, whereas the peripheral nervous system is made of nerves arising from the ganglia.
- Supra oesophageal ganglion:-
- are a pair of ganglia found in the head & form the brain.
- Circum oesophageal Connectives:-These are thick ends of nervous tissue arising from the base of the brain and called commissures.
- Sub oesophageal ganglia:- are a pair of ganglia the oesophagus. They give off several nerves to the mouth parts.
- Ventral nerve end cord segmental ganglia:- The double ventral nerve cord arises from the base of the sub oesophageal ganglia, and runs to the end of the body. There are nine segmental ganglia, of which three pairs are thoracic, six pairs in the abdomen i. e 1st five lie in the first five abdominal segments, the last is large & found farther behind.
- The thoracic ganglia give out nerves to the muscles of legs and wings and abdominal ganglia give out nerves to abdominal muscles, heart, spiracles & reproductive organs.
