Cockroach: Digestive and Blood Vascular System, Practice Problems and FAQ

Do you know cockroaches live for a week without a head? 

This happens because they have an open circulatory system in which blood does not flow through blood vessels. Moreover, they breathe through tiny holes that are present in each segment of their body. So, they do not depend on their head or mouth for breathing. 

Let’s take a deep dive into the digestive and blood vascular system of cockroaches. 

Table of Contents:

• Anatomy of Cockroach
• Digestive System
• Blood Vascular System
• Practice Problems on Cockroaches
• FAQs on Cockroaches

Anatomy of Cockroach

The major organ systems present in cockroaches are listed below:

• Digestive system
• Blood vascular system
• Respiratory system
• Excretory system
• Nervous system
• Reproductive system

Digestive System

The digestive system of cockroaches is divided into three parts. These are foregut, midgut and hindgut.

Foregut

Foregut is lined with cuticles. It consists of mouth, pharynx, oesophagus, crop and gizzard.

• Mouth - Foregut starts from the mouth. It leads to the pharynx.
• Pharynx - It is present between mouth and oesophagus.
• Oesophagus - It is a narrow tubular passage that opens into the crop.
• Crop - It is a wide sac used for storing food. It leads into a gizzard.

Gizzard - It is also called proventriculus. It helps in grinding food. Its outer layer is made up of circular muscles. Inner layer is made up of a cuticle that forms chitinous teeth. It helps in grinding of food particles.

Midgut

Midgut is also known as mesenteron. It consists of two parts: Hepatic caeca and malpighian tubules. 

Hepatic Caeca 

It is present at the junction of foregut and midgut. These are 6 – 8 blind tubules. They secrete digestive juices. These digestive juices help in digestion and absorption. 

Malpighian Tubules 

These are 100 – 150 yellow coloured thin filamentous structures. They help in excretion. They remove excretory wastes from the blood.

Hindgut

Hindgut is broader than midgut. It consists of three regions as follows: 

• Ileum - It is short and narrow.
• Colon - It is long coiled.
• Rectum - It is short and wide. It opens outside through anus.

Blood Vascular System

Open type blood vascular system is present in cockroaches. In this system blood does not flow through blood vessels, rather blood is pumped into the body cavity. It consists of haemocoel, heart and hemolymph. 

Haemocoel 

Haemocoel is a body cavity filled with blood where visceral organs are located. The body cavity is divided into three sinuses by dorsal and ventral diaphragms. These sinuses are pericardial sinus, perivisceral sinus and perineural sinus.

• Pericardial sinus - Heart is present in this sinus. It is present on the dorsal side below the terga.
• Perivisceral sinus - Visceral organs are present in this sinus. It is the middle space.
• Perineural sinus - Nerve cord is present in this sinus. It lies on the ventral side above the sterna.

Heart

The heart is present in the pericardial sinus. It is an elongated muscular tube that lies along the mid dorsal line of the thorax and abdomen. It consists of 13 funnel shaped chambers. Ostia is present on either side of the funnel-shaped chambers. Heart pumps blood as it is associated with alary muscles.

Hemolymph

Hemolymph is the circulatory fluid in cockroaches. It does not flow through blood vessels. It helps in the transportation of nutrients and also maintains hydrostatic pressure. It acts as the reservoir of water. Visceral organs bathe in the hemolymph. No respiratory pigments are present in hemolymph. It is composed of colourless plasma and haemocytes. 

• Plasma - It contains amino acids and uric acids.
• Haemocytes - They are responsible for phagocytosis, coagulation and wound healing.

Circulation

The contraction of the alary muscles stretches the diaphragm. It results in an increase in the volume of pericardial sinus. So blood from the perivisceral sinus enters the heart through ostia. Relaxation of the muscles results in the entry of blood from the pericardial sinus into the heart through ostia. Heart pumps the blood into the head sinus through the aorta. The blood again enters the perivisceral and perineural sinus through the aorta.

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Practice Problems of Cockroaches

Ques:- Which part of the cockroach is also referred to as mesenteron?

A. Foregut
B. Midgut
C. Hindgut
D. Heart

Solution: Midgut is also known as mesenteron. It consists of two parts: hepatic caeca and malpighian tubules. Hepatic caeca is present at the junction of foregut and midgut. They secrete digestive juices that help in digestion and absorption. Malpighian tubules are 100 – 150 yellow coloured thin filamentous structures that help in excretion. 

Ques:- Which of the following structures is responsible for excretion in cockroaches?

A. Malpighian tubules
B. Hepatic caeca
C. Gizzard
D. Crop

Solution: Malpighian tubules are 100 – 150 yellow coloured thin filamentous structures. They are a part of midgut and help in excretion. They remove excretory wastes from the blood. Hence, the correct option is a.

Ques:- Label the parts of the hindgut in the given figure.

Solution: In the given figure, ‘a’ represents ileum, ‘b’ represents rectum and ‘c’ represents colon. Ileum is short and narrow. Colon is long coiled. Rectum is short and wide. It opens outside through anus.

Ques:- In which sinus the heart of cockroach is present?

A. Pericardial sinus
B. Perivisceral sinus
C. Perineural sinus
D. Both a and b

Solution: The heart is present in the pericardial sinus. The heart of a cockroach is an elongated muscular tube that lies along the mid dorsal line of the thorax and abdomen. It consists of 13 funnel shaped chambers. Hence, the correct option is a.

FAQs of Cockroaches

Ques:- What is hemolymph?

Solution: Hemolymph is the circulatory fluid in cockroaches. It does not flow through blood vessels. The nutrient transfer is aided by hemolymph and keeps the hydrostatic pressure constant. It serves as a water reservoir. Visceral organs bathe in the hemolymph. It is composed of colourless plasma and haemocytes. 

Ques:- In cockroaches, are blood vessels present or not?

Solution: In cockroaches, an open type blood vascular system is present. Blood does not flow through blood vessels, rather blood or hemolymph is pumped into the body cavity. It consists of haemocoel, heart and hemolymph. Therefore, cockroaches do not have blood vessels.

Ques:-What is the function of gizzard in cockroaches?

Solution: Gizzard helps in grinding food particles. The outer layer is made up of circular muscles. Inner layer is made up of a cuticle that forms chitinous teeth. Gizzard is also called proventriculus.

Ques:- Why do cockroaches possess an open circulatory system?
Solution: Cockroaches have an open circulatory system because they do not have blood vessels in which blood flows. Apart from this, cockroaches have a cavity called hemocoel in which blood and visceral organs are present.

Related Topics to Digestive System of Cockroach in Biology

• Morphology of Cockroach
• Respiratory system of cockroaches
• Reproductive system of cockroach
• Connective Tissues
• Connective Tissue Blood
• Connective Tissue Bone
• Connective Tissue Cartilage

NCERT Class 11 Biology Chapters