Circulatory System Of Cockroach

Overview of Circulatory System in Cockroach

The cockroach maintains an open circulatory system where hemolymph bathes its organs directly in a primary body cavity called the hemocoel.

• Open circulatory system: The hemolymph flows in body cavities but is not restricted to the vessels.

• Hemolymph: The cockroach circulates the hemolymph that is home to wastes, nutrients and immune cells in vertebrates.

• Hemocoel: The hemolymph flows in the primary body cavity.

• Dorsal Vessel: Comprises the heart and aorta; it propels hemolymph throughout the body.

• Alary Muscles: Aid the dorsal vessel in moving the hemolymph into the body by spontaneous contraction and relaxation of the alary muscles.

• Ostia: A series of openings in the heart of the cockroach, allowing hemolymph to enter the heart from the hemocoel.

Structure of Cockroach Circulatory System

Hemolymph is pumped by the heart through a few arteries but is not contained in blood vessels with speed to all internal areas of the body where it otherwise has direct interaction with internal organs.

Hemocoel

During development of the body cavity, the blastocoel is not completely obliterated by the mesoderm and fuses with embryonic coelomic cavities. It fills most of the body volume with freely moving hemolymph. It has three compartments: perivisceral, perineural, and pericardial sinuses

Dorsal Vessel (Heart + Aorta)

It is located at the dorsal midline of the thorax and abdomen. The heart is tubular with segmental chambers

Function:

• Pumps hemolymph from organs through the aorta into the hemocoel.

• Peristaltic waves push hemolymph.

Ostia: Inflow Openings

These are valves that allow hemolymph to enter the heart from the pericardial sinus. It ensures one-way flow into the heart.

Pericardial Sinus

It is a cavity that surrounds the heart, and is physically isolated from the perivisceral sinus by a dorsal diaphragm. It collects hemolymph blood through the heart.

Alary Muscles

Alary muscles are attached to the heart to dorsal diaphragm. Its contraction lags in the movement of hemolymph by the heart

Composition & Functions of Hemolymph

Hemolymph is a colorless fluid that serves as the blood of the insect.

• Composition: Contains plasma, hemocytes (immune cells), nutrients, and waste products.

• Function: Distributes nutrients, removes waste, and participates in immune responses.

Working of Cockroach Circulatory System

The cockroach has an open circulation. In cockroaches, the heart and all viscera lie in the hemocoel, bathed by blood (hemolymph).

Circulatory Mechanism

• The heart is made up of a dorsal vessel, which contracts on its own in the sequence that helps to pump the hemolymph.

• Blood enters the heart through valved openings, the ostia, and the heart’s contractions, which resemble a forward-moving peristaltic wave, propel blood into a limited arterial system.

• Blood is distributed to the head and other organs, then escapes into the hemocoel. It is routed through the body and appendages by a system of baffles and longitudinal membranes (septa) before returning to the heart.

• Hemolymph returns to the heart through the ostia during relaxation.

Role Of Muscular Contractions

• Alary Muscles: Assist heart contractions, thus ensuring the energy released is optimally directed to move the hemolymph.

• Diaphragm Movements: Assist in pressure changes that help to keep circulation moving.

Adaptations, Benefits & Limitations

The open circulatory system of the cockroach has benefits as well as limitations.

Benefits

• Fast Distribution: Allows food and waste to be transported rapidly to its body.

• Simple Design: Simplicity, fewer number of structures, ideal for small organisms.

• Low Energy Required: Requires less energy to operate and maintain

Limitations

• Inefficient Supply: Less effective at rapidly transporting oxygen and nutrients to tissue and cells, hence makes it unsuitable for large organisms.

• Reduced Control: Less control over where and how much blood flows to specific organs and tissue.

• Slow Flow Rate: Blood flow is slow as hemolymph circulation relies on the organism's body movement.

Physiological Role Of Circulatory System

The system therefore assumes systemic existence by linking body parts.

• Nutrient Transport: From the gut, nutrients are distributed to body cells.

• Waste Removal: Metabolic wastes are transported to excretory organs.

• Immune Responses: Hemocytes provide immune defense.

• Thermoregulation: This function is involved in the distribution of heat over the body.

Comparison: Cockroach vs Human Circulatory System

The circulatory system of cockroaches is quite different from that of humans. Let’s take a look at the differences between the two.

Cockroach Circulatory System NEET MCQs (With Answers & Explanations)

Important topics for NEET exam are:

• Structure of Circulatory System

• Comparison between Human and Cockroach circulatory system

Practice Questions for NEET

Q1. In cockroach , heart comprises of

1. 4 chamber

2. 2 chamber

3. 8 chamber

4. 13 chamber

Correct answer: 4) 13 chamber

Explanation:

As we have learned

Cockroach heart -

The heart of a cockroach is a long elongated muscular tube lying along the mid-dorsal line of the thorax and abdomen. It is differentiated into funnel-shaped 13 chambers with ostia on either side.

Hence, the correct answer is option 4) 13 chamber.

Q2. Which of the following is true regarding the circulatory system of the cockroach?

1. It is of open type.

2. It has well-developed blood vessels.

3. It is regulated by a neural and tubular heart.

4. It is made up of cells and plasma containing haemoglobin.

Correct answer: 1) It is of open type

Explanation:

The circulatory system of the cockroach is open.

The blood (or hemolymph) is not restricted to blood vessels in an open circulatory system. Rather, it freely circulates through sinuses or cavities around the organs directly soaking them in the fluid. In disparity, blood is always contained within blood vessels in a closed circulatory system.

Hence, the correct answer is option 1)It is of open type.

Q3. The visceral organs of the cockroach are present in _____ surrounded with ______.

1. Coelom; lymph

2. Pseudocoelom; blood

3. Haemocoel; hemolymph

4. None of these

Correct answer: 3) Haemocoel; hemolymph

Explanation:

The visceral organs of cockroaches are situated in the hemocoel, a spacious cavity within the organism. This cavity is integral to the open circulatory setup, as it allows for the unmediated contact of hemolymph, which serves akin to blood in insects, with the digestive, excretory, and reproductive systems. Unlike the closed circulatory system, where blood is confined to vessels, the open system directly surrounds the organs for efficient nutrient and oxygen distribution.

Hence, the correct answer is option 3) Haemocoel; hemolymph.

Also Read:

• MCQs on Circulatory System of Cockroach

• Digestive System of Frog

• Connective Tissues