Digestive system of cockroach

Digestive system of cockroach by Dr.Kshirsagar R.V.

1. DISSECTION OF COCKROACH
DIGESTIVE SYSTEM OF COCKROACH
BY
DR.RAVINDRA V.KSHIRSAGAR
M.Sc. Ph.D FGSBAS
Department of Zoology
Modern college of Arts, Commerce and Science,
Ganeshkhind .Pune

2. Students learn skill of dissection.
Students identify different parts of the digestive
system.
Students describe mechanism of digestion.
Students discuss comparison of digestive system.

5. Digestive System FOREGUT
Thealimentarycanalis
dividedintothreemain
portions-
Foregut
Foregutconsistsofthemouth
surroundedbythemouthparts.
Themouthcavityiscalledthe
pharynx.
Itcontinuesastheoesophagus
thatisshort,narrowandthin-
walled.Thecanalthenenlarges
intothecrop,whichisalsothin-
walled.
Thecropopensintoashort,
muscularorgan,thegizzardor
theproventriculus.Outsideand
lyingbelowthecropareapair
ofsalivaryglands.

6. Midgut
Midgutformsthetruegutorthemesenteronandconsistsentirelyofstomachorventriculus.
Atthejunctionofthegizzardandstomacharesixpairsofgastriccaecae('gastric'meanspertainingto
stomach).
Thesearepouch-likestructuresarrangedinaring-likemanneraroundtheanteriorendofthestomach.
Theanteriorlobeofeachpairofthecaecaeextendsovertheproventriculusandtheposteriorlobe
extendsovertheventriculus.
Thecaecaesecretedigestivejuicesandpourthemintothestomach.
Themidgutisnotlinedbychitinorcuticlebutbyaperitrophicmembrane.Thismembraneprotectsthe
stomachwallfromabrasionsandisfullypermeabletoenzymesanddigestedfood.

7. Hindgut is a coiled structure consisting of
anterior ileum, middle colon and posterior
rectum.
The rectum opens to the exterior through the
anus.
The hindgut is lined by cuticle.
At the junction of the stomach and ileum are
attached numerous long tubules called the
Malpighian tubules.

8. MechanismofDigestion
Digestionstartsinthemouthwiththemandiblesandthe
maxillaechewingthefood.Itisalsoacteduponbythesalivary
carbohydraseswhichpartiallydigeststhefood.
Thefoodisthenswallowedwiththehelpoflubricationprovided
bythesalivaryjuice.
Thefoodthenenterstheoesophagusandthenintothecrop.
Here,themasticatedfoodistemporarilystored.
Thefoodisthenpassedintothegizzardwhichactsasthe
grindingchamber.
Atthejunctionofthegizzardandthestomachisavalvecalled
thestomodaelvalve.
Itallowsthepassageofonlythethoroughlydigestedfoodinto
thestomachandalso,preventstheregurgitationoffoodfromthe
stomach

9. The ground food, then enters thestomach. The digestive
enzymes secreted by the gastric caecaeact upon the food in the
stomach.
These enzymes include amylase, maltase, invertase, tryptaseand
lipase. The remaining carbohydrates, proteins and fats are
digested here.
The digested food is absorbed through the stomach walls into the
surrounding space which is called thehaemocoel.
The haemocoelconsists of a large number of fat bodies which are
fat cells having fat globules, protein granules and glycogen.
They form storage structures. From here, it is transported to the
different body parts.