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Difference Between Open and Closed Circulatory System

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Last updated date: 25th Jul 2024
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Introduction: Circulatory System in Animals

Circulatory systems play a crucial role in transporting essential substances, such as oxygen, nutrients, hormones, and waste products, throughout an organism's body. They facilitate the exchange of gases, nutrients, and other vital molecules, ensuring the proper functioning of cells and organs. Two main types of circulatory systems are observed in the animal kingdom: open circulatory systems and closed circulatory systems. In this article we will explore the difference between open and closed circulatory system. Learn about the difference between open and closed circulatory system, explain open and closed circulatory system, open and closed circulatory system difference, what is open and closed circulatory system, characteristics of open and closed circulatory system.

What is Open and Closed Circulatory System?

Open Circulatory System:

An open circulatory system is a circulatory system in which the circulating fluid, known as hemolymph, directly bathes the organs and tissues. Hemolymph is pumped by the heart into interconnected spaces called sinuses or hemocoels. From there, it diffuses through the body cavities, directly contacting the cells and facilitating the exchange of nutrients and waste products. In an open circulatory system, the hemolymph is not confined to blood vessels.


Closed Circulatory System:

In contrast, a closed circulatory system is a circulatory system in which the circulating fluid, known as blood, is enclosed within a network of blood vessels. The blood is pumped by the heart and travels through arteries, capillaries, and veins, forming a closed circuit. This closed system allows for more precise control over blood flow and distribution of substances throughout the body.


Components of Open and Closed Circulatory Systems

Open and closed circulatory systems have different components that contribute to their functioning.


In an Open Circulatory System:


1. Hemolymph: This is the fluid that circulates within the body cavity, directly bathing the organs and tissues. It consists of a mixture of blood and interstitial fluid.


2. Heart: The heart in an open circulatory system is a simple structure that pumps the hemolymph into the body cavity.


3. Sinuses: The hemolymph flows through sinuses or spaces located between organs, facilitating exchange with the cells.


4. Hemocoel: The hemocoel is the main body cavity where the hemolymph flows and is distributed to different regions of the body.


In a Closed Circulatory System:


1. Blood: The blood in a closed circulatory system is contained within blood vessels and consists of plasma and various types of blood cells.


2. Heart: The heart is a muscular organ responsible for pumping the blood throughout the body.


3. Blood Vessels: Arteries carry oxygenated blood away from the heart, while veins carry deoxygenated blood back to the heart. Capillaries are the smallest blood vessels where exchange of substances between blood and tissues occurs.


4. Red Blood Cells: These cells contain hemoglobin and are responsible for carrying oxygen to the tissues.


5. White Blood Cells: These cells play a role in immune defense and protection against infections.


6. Platelets: Platelets are involved in blood clotting to prevent excessive bleeding.


The components of both open and closed circulatory systems work together to ensure the circulation of vital substances and the maintenance of proper physiological functions within an organism's body.


Characteristics of Open and Closed Circulatory System:

Characteristics of Open Circulatory System:

1. Hemolymph: In an open circulatory system, the circulating fluid is called hemolymph. It is a mixture of blood and interstitial fluid and directly bathes the organs and tissues.


2. Lack of Blood Vessels: Open circulatory systems lack a network of blood vessels. Instead, the hemolymph flows through sinuses or spaces located between organs.


3. Limited Control: The flow of hemolymph is not as precisely controlled as in a closed circulatory system. It diffuses freely through the body cavity and comes into direct contact with cells.


4. Lower Pressure: The absence of a closed vessel system results in lower blood pressure compared to closed circulatory systems.


5. Simplicity: Open circulatory systems are relatively simpler in structure and require fewer specialized components.


Characteristics of Closed Circulatory System:

1. Blood: In a closed circulatory system, the circulating fluid is blood, which is contained within a network of blood vessels.


2. Specialized Blood Vessels: Closed circulatory systems have arteries, veins, and capillaries that form a closed loop. Arteries carry oxygenated blood away from the heart, veins carry deoxygenated blood back to the heart, and capillaries allow for exchange between the blood and surrounding tissues.


3. Precise Control: The closed circulatory system allows for precise control of blood flow to specific organs and tissues. Blood flow can be regulated through constriction or dilation of blood vessels.


4. Higher Pressure: The presence of a closed vessel system enables higher blood pressure, facilitating efficient delivery of oxygen, nutrients, and hormones to target areas.


5. Enhanced Efficiency: Closed circulatory systems are more efficient in delivering substances to specific locations, enabling higher metabolic rates and supporting active and complex organisms.


Difference Between Open and Closed Circulatory System

Sr No.

Features

Open Circulatory System

Closed Circulatory System

1

Circulating Fluid

Hemolymph

Blood

2

Blood Vessels

Hemocoels, sinuses

Arteries, veins, capillaries

3

Direct Contact with Cells

Yes 

No

4

Efficiency

Relatively lower

Relatively higher

5

Control over Blood Flow

Limited

Precise

6

Found in

Found in invertebrates such as insects, mollusks

Found in vertebrates and some invertebrates like annelids and cephalopods


Summary

Open and closed circulatory systems are two distinct mechanisms by which organisms transport vital substances throughout their bodies. Open circulatory systems lack blood vessels, while closed circulatory systems have a well-defined network of vessels. Open systems provide a more generalized distribution of fluids, while closed systems offer precise control over blood flow. Understanding the characteristics and functions of these circulatory systems provides insights into the remarkable adaptations of different organisms and their survival strategies.

FAQs on Difference Between Open and Closed Circulatory System

1. What are the main components of a closed circulatory system?

The main components of a closed circulatory system consist of the heart, blood, and blood vessels. The heart acts as a pump to propel blood throughout the body, supplying oxygen and nutrients to tissues and organs. Blood serves as the transport medium, carrying oxygen, nutrients, hormones, and waste products. The blood vessels, including capillaries, veins, and arteries, form a network that enables the circulation of blood. Arteries carry oxygenated blood away from the heart, while veins return deoxygenated blood back to the heart. Capillaries facilitate the exchange of substances between the blood and tissues. Together, these components work in harmony to ensure efficient circulation and proper functioning of the closed circulatory system.

2. What are the components involved in an open circulatory system?

In an open circulatory system, the main components include a blood cavity, body and cavity muscles, and a circulatory fluid. The blood cavity serves as a storage and movement space for blood, while the body and cavity muscles contract to pump the blood into the body cavity. The circulatory fluid, which is not contained within blood vessels, directly bathes the organs and tissues, providing oxygen and nutrients. Unlike a closed circulatory system, where blood is contained within vessels, an open circulatory system relies on these components to facilitate the circulation of fluids throughout the body.

3. What is the primary difference between open and closed circulatory systems?

The primary difference between open and closed circulatory systems lies in how the blood is distributed. In an open circulatory system, blood is released into open spaces called the blood cavity and directly bathes the organs and tissues. This type of circulation is termed "open" because there is no continuous network of blood vessels. In contrast, a closed circulatory system involves blood circulating within a closed network of vessels, such as arteries, veins, and capillaries. The blood remains confined within these vessels, supplying oxygen and nutrients to the organs and tissues. This type of circulation is termed "closed" as the blood follows a specific pathway without being released into open spaces.