Digestive system Alimentary Canal Of Cockroach

What is the Digestive System of Cockroach?

A cockroach has a well-developed digestive system, along an elongated coiled alimentary canal that portends into three divisions; the foregut, midgut, and hindgut.

Alimentary Canal of Cockroach

The digestive system consists of an alimentary canal which is divided into three regions i.e. foregut, midgut, and hindgut

Foregut (Buccal cavity, pharynx, oesophagus, crop, gizzard)

• The foregut of a cockroach consists of the buccal cavity, pharynx, oesophagus, crop, and gizzard.

• The food, after being properly softened by the mouth parts, enters the buccal cavity.

• Then the pharynx acts as a sucking pump and takes in the food through the oesophagus, which is connected with the crop.

• The crop is an organ of food storage that helps the cockroach store its food for digestion little by little.

• The proventriculus or gizzard has inner chitinous plates and thick-walled muscular, suitable for crushing the food into finer particles.

• Each salivary gland contains many branches, each of which has different secretions that run to a single tube.

• Both salivary glands have a reservoir that resembles a bladder as their salivary receptacle.

• These serve primarily as salivary secretion storage. A rectangular-shaped combined/common route that connects to the combined salivary passage is present in both receptacles.

• The combined salivary passage opens up the area of the mouth close to the labium. The entire foregut forms the lining of the chitin. The proventricular teeth and the plate are made by the chitin to aid in the process of food grinding.

Midgut (Mesenteron with hepatic caeca)

• The midgut is short compared to the foregut and is lined with glandular endoderm.

• There are eight blind globular hepatic caeca between the gizzard and midgut, which have digestive enzymes that secrete to help in the chemical digestion of food.

• The enzymes hydrolyze the complex molecules into simple ones so the body can absorb them.

Hindgut (Ileum, colon, rectum, anus)

• Hindgut consists of ileum, colon and rectum.

• The ileum is a short segment which ducts of Malpighian tubules, and excretory organs open into.

• The colon is a long thin segment and the rectum forms a short and wide segment opening out through the anus.

• The hindgut comprises the final phases of digestion, absorption of water and elimination of waste products.

Digestive Enzymes And Absorption

The mouth, where the mandibles and maxillae help to chew the food, is where digestion first starts. Salivary carbohydrates, a component, partially digest food

Role of Salivary Glands

• Saliva lubricates the food and facilitates swallowing.

• The meal then travels via the oesophagus into the crop. This is the location where masticated food is temporarily stored.

• Then, the food passes into the gizzard, which is a muscular part of the digestive system. The gizzard grinds the food into smaller particles with the help of chitinous plates or teeth present in its walls. At the junction of the crop and the gizzard, there is a valve called the stomodeal valve.

• This valve controls the movement of food from the crop into the gizzard and prevents the backward flow of food.

Gastric Caeca and Enzymes

• The digestive enzymes produced by the gastric caeca handle the food once it reaches the stomach.

• The hepatic caeca and other caecal-type glands connected to the alimentary canal secrete digestive enzymes that act upon the complex food molecules and convert them into simpler molecules that can be absorbed including amino acids, monosaccharides, and fatty acids.

Absorption into Hemolymph

• The digested food is broken down into small molecules, which are absorbed through the walls of the midgut and hindgut.

• These nutrients then enter the hemolymph, which is the cockroach’s equivalent of blood.

• The hemolymph circulates these nutrients to different tissues of the body for energy and growth.

Excretion in Cockroach

The process of excretion occurs through Malpighian tubules.

• The excretory organs of cockroaches are the Malpighian tubules attached to the ileum.

• The tubules filter waste products from the hemolymph and carry them into the hindgut for expulsion outside through the anus.

• This also helps the cockroach maintain their water balance and ions in their body.

Dentition For Omnivorous Feeding

Cockroaches are omnivorous, and hence they feed on a wide variety of food sources: plants, dead organic matter, and other insects. Their digestive system is well fitted to this type of diet. The crop stores food, the gizzard grinds it, and the midgut and hindgut further digest and absorb nutrients from various types of food.

Digestive System of Cockroach NEET MCQs (With Answers & Explanations)

This topic carries a significant weightage in NEET exam. Important topics to be covered are:

• Alimentary canal (foregut, midgut, hindgut)

• Function of different organs (crop, gizzard)

• Digestive enzymes

Practice Questions for NEET

Q1. Which of the following is correctly stated as it happens in the common cockroach?

1. Malpighian tubules are excretory organs projecting out from the colon.

2. Oxygen is transported by haemoglobin in the blood.

3. The nitrogenous excretory product is urea.

4. The food is ground by mandibles and gizzard.

Correct answer: 4) The food is ground by mandibles and gizzard.

Explanation:

The food is ground by mandibles and gizzards in the common cockroach.

The gizzard also known as the proventriculus, is a muscular structure lined with chitinous plates that further grinds food before it enters the midgut for digestion. In cockroaches, the mandibles aid in chopping and crushing food. Cockroaches can more effectively digest solid food particles thanks to this adaption.

Hence, the correct answer is option 4)The food is ground by mandibles and gizzard.

Q2. The teeth of the cockroach are present in

1. Buccal chamber

2. Crop

3. Pharynx

4. Gizzard

Correct answer: 4) Gizzard

Explanation:

The gizzard is an important part of the foregut, and it has a thick inner cuticle in the form of six highly chitinous plates, often referred to as teeth. These plates play a crucial role in the gizzard's function, which is to grind food particles. The grinding action helps break down food into smaller pieces, making it easier for digestive enzymes in the midgut to further process and absorb nutrients. This mechanical digestion in the gizzard is an essential part of the overall digestive process in animals with this specialized foregut structure.

Hence, the correct answer is option 4) Gizzard.

Q3. The digestion and absorption in the cockroach occurs in

1. Foregut

2. Hepatic caeca

3. Midgut

4. Hindgut

Correct answer: 3) Midgut

Explanation:

The midgut is the portion of the alimentary canal located between the hepatic caeca (anterior) and the Malpighian tubules (posterior). It forms the true stomach and is primarily responsible for digestion and absorption of nutrients. Digestive enzymes secreted by the midgut and hepatic caeca break down complex food molecules into simpler forms for absorption. The epithelial lining of the midgut is specialized for nutrient uptake, ensuring efficient transfer of digested materials into the hemolymph. Additionally, the midgut lacks a cuticular lining, which facilitates direct interaction with food and enzymes, unlike the foregut and hindgut. It also plays a role in maintaining the insect’s internal pH and detoxifying harmful substances.

Hence, the correct answer is option 3) Midgut

Also Read:

• MCQs on Digestive System of Cockroach

• Digestive System of Earthworm

• Reproduction System of Cockroach