DIGESTIVE SYSTEM IN COCKROACH

ALIMENTARY CANAL

6-8 cm. long. Coiled, present from mouth to anus.

Differentiated into 3 parts -      1. Foregut            2. Midgut        3. Hindgut

1.      FOREGUT

1. Differentiated into pharynx, oesophagus, crop and gizzard.
2. Pharynx is small tube like, present in neck.
3. Pharynx is attached to oesophagus in thorax.
4. Oesophagus forms crop (a sac like) upto 4th segment of abdomen.
5. In crop food is stored & complete digestion takes place.
6. At the base of crop gizzard or proventriculus present. Helpfull in grinding of food.
7. Anterior part of gizzard is armarium, in it 6 denticles present made up of cuticle.
8. Posterior part of gizzard is stomodeum in which 1 pair hairy pad pulvillus & 1 pair stomodeal valve present, allow only finnest particles of food.

2.      MID GUT

1. Walls are soft and glandular. Starting point of mid gut is cardia.Digestion and absorption takes place in it.
2. At the junction of mid gut and foregut 8 Hepatic ceacae present, secrete digestive juice that do digestion in crop.
3. Secretion of stomodeal valve (Cardia) in mid gut forms peritrophic membrane around food to protect wall of mid gut.

3.      HIND GUT

1. Differentiated into Iluem, colon & rectum.
2. In ileum 6 spicules present function as sphinctor & tear off the peritrophic membrane.
3. In colon undigested food is converted into faeces.
4. In rectum on external surface 6 rectal ridges present alternate with 6 rectal pads on inner side.
5. Maximum water is reabsorbed. Rectum opens outside by anus in 10th segment.
6. Anus is controlled by 4 podical plates.