Digestive system of Cockroach q The digestive system

Digestive system of Cockroach q The digestive system of cockroach consists of alimentary canal & digestive glands. Alimentary Canal § Foregut: ( mouth, pre-oral cavity, buccal cavity, oesophagus, crop & Gizzard) § Midgut: ( Hepatic or enteric coeca & malpighian tubules. ) § Hind gut: ( ileum, colon & rectum , rectal papillae)

Gizzard (Proventriculus) § Lying behind the crop is a small, thick walled, muscular and cone-shaped crop. § It consists of an anterior armarium and a posterior stomodeal valve. § The armarium possesses internally six longitudinal folds that greatly reduce its lumen. § These folds alternate with six grooves. § The lining of each fold forms, (1) anteriorly a thick plate produced in to strong teeth, (2) in the posterior part a thin plate. § Behind each fold, the lining of gizzard forms a soft cushion-like lobe, the pad or pulvillus with long backwardly directed hair. § Behind the pad the gizzard extends into the lumen of midgut as a stomodael valve.

Digestive glands: Digestive glands of cockroach include the salivary glands, the glandular cells of midgut & hepatic caeca. § Salivary glands: § A pair of glands one on either side of the crop in thorax, are found associated with alimentary canal. § Each gland consisting of several secreting lobules or acini in grape- like clusters & connected together by fine tubules. § The acini contain 2 types of saliva secreting cells, zymogen cells and ductule containing cells. § Saliva consists of en enzyme zymase & mucoid substance. § From the glandular portions of the two sides arise salivary duct which unite to form a common duct.

§ Likewise, two ducts from the reservoirs(storage of saliva) also join to form another common duct. § The two common ducts join to form an efferent salivary duct which opens in the pre-oral cavity at the base of hypopharynx. § The glandular cells of midgut & hepatic caeca also produce the juice containing digestive enzymes.

§ Food Feeding & Digestion: § The cockroach is a omnivorous. § The food is searched by the sweeping antennae and seized by the forelegs, labrum and labium. § During the mastication the teeth of mandibles bite and chew the food. § The chewed food is pushed into pre-oral cavity by maxillae, prostheca of mandibles & labium and then it is swallowed into the mouth. § The crushed food is acted upon by the saliva, whose mucoid substance lubricates the food and enzyme zymase hydrolyses the starch. § After reaching into the crop, the digested carbohydrate in the form of glucose is absorbed & remaining food comes across the secretion of the glandular cells of midgut.

§ Upon entering the crop, the food is again subjected to mastication by internal denticles. § In the midgut the partly digested food is mixed with the enzymatic substances of cells of hepatic caeca. § The secretions are… § Trypsin like enzyme & peptidases. . Break down proteins. § Amylase … break down starch (carbohydrate) and § Lipase… break down fat. § A thin, transparent, chitinous peritrophic membrane lines the midgut internally. § It is permeable to enzymes as well as digested food. § The epithelial cells of hepatic caeca & midgut are also absorptive. § The undigested food is passed in to Ileum Colon Rectum Anus faeces (dry pellets).