Question

Describe the digestive system of cockroach with the help of a neat labelled diagram? (KS)

Answer 1

Digestive system in cockroach:

Cockroach is an omnivorous. It can eat all kinds of organic matter. The nutrition in cockroach is holozoic.



THE DIAGRAM SHOWS THE DIGESTIVE SYSTEM OF

PARTS OF ALIMENTARY CANAL:

The alimentary canal is divided into three main parts:

Foregut:

It is the first section of the alimentary canal. It consists of the mouth. The mouth followed by the buccal cavity. Inside the buccal cavity there is a tongue and hypo pharynx.

Buccal cavity opens into pharynx. The pharynx continues as the oesophagus. The oesophagus is a small, narrow tabular structure which is followed by a large sac like structure known as crop. The crop is a storage bag of the food material.

Important point:

The buccal cavity receives the common duct of salivary glands. Cockroach has a pair of salivary glands. Saliva contains amylase which converts starch into sugar.

The oesophagus is short in the length tabular structure while crop is large pear shaped structure. But both are thin walled structure.

Gizzard is a small, rounded thick walled with muscular chitins lining structure. It has six teeth. These teeth are sharp to grind the food. Gizzard masticates the food.

Midgut:

It is also known as mesentrone. It narrow, short and tabular structure. At the junction of gizzard and mesentron there are 6-7 small finger like projection known as hepathic caeca. These are hanging in the haemocoel ending blindly but opening in the midgut.

Important point:

The white color blood which filled in the body cavity is known as heamocoel.

Function:

Hepatic caeca produces digestive enzymes. With the help of these digestive enzymes the digestion of food takes place in the mesentron. After the digestion the nutrient such as carbohydrates, fats and proteins are absorbed by the midgut, especially in the more anterior parts including the caeca. All the nutrients are absorbed. Remaining nutrients and water are absorbed in the hindgut especially in the rectum.

Hindgut:

It has three main parts:

Ileum:

It is a small, narrow, tabular part. It absorbs the remaining nutrients.

Colon:

It is highly coiled structure.

Rectum:

It is broad last part of the hindgut. It stores undigested food for some time.

 

Anus:

It is the last opening of digestive system. It opens to outside and undigested food is expel as feaces.

At the junction of mesentron and the hindgut, there are so many (60-120) light pale, threads like structures are present which are known as malphighian tubules.

Function of malphighian tubles:

It helps in excretion.

Mechanism of the digestion:

In the buccal cavity:

Digestion starts in the buccal cavity with the help of salivary amylase. Salivary amylase converts starch into sugar.

In the mesentron:

It acts like a stomach of human. Here digestive enzymes are poured by hepatic caeca. These digestive enzymes contain: gastric amylase, maltase, invertage tryptase and lipase.

The digestion of carbohydrates, proteins and fats is completed.

The digested food is reached in the haemocoel where some food is used to release energy for daily metabolic activities and extra digested food is stored in the form of glycogen, fats granules and protein granules in the heamocoel. From here it is transported to different body parts

Answer 2

first three parts of the digestive system of the cockroach are the pharynx, Esophagus and the salivary glands. Pharynx is the 1st major part which leads into the esophagus which is the duct that move food towards the stomach. salivary glands produce saliva. crop is analogous to the stomach and gizzard helps in digestion. then it move from the intestine to the rectum which is the last part of the digestive tract.