Double Circulation -Definition, 2 Loops, Flowchart,Types, Importance

Double Circulation in Human Beings Why is it Necessary - Class 10

Double Circulation -Definition

Double Circulation is a Circulatory System found in some animals that consists of two separate loops of circulation through the body-  Pulmonary Circulation and Systemic circulation. This allows for more efficient delivery of oxygen and nutrients to the body’s tissues and effective removal of waste products.

The Circulatory System

The Circulatory System is responsible for the transportation of nutrients, gases and waste products. It plays a crucial role in maintaining homeostasis in the body, which is the balance of various physiological processes. Nutrients such as glucose, amino acids and fatty acids are transported from the digestive system to the cells and tissues of the body through the Circulatory System. Oxygen is also transported through the Circulatory System to cells for cellular respiration and carbon dioxide, a waste product of cellular respiration, is transported away from cells and ultimately eliminated from the body.

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2 Types of Circulatory Systems

There are two main types of Circulatory Systems found in animals

  • Open Circulatory Systems 
  • Closed Circulatory Systems.

Open Circulatory Systems

In an open Circulatory System  the circulatory fluid called as hemolymph is not always enclosed in vessels. Instead, the fluid is pumped by a Heart into a cavity called the hemocoel. From there the fluid bathes the organs and tissues directly. This type of system is found in many invertebrates such as insects, crustaceans and mollusks.

Closed Circulatory Systems

In a closed Circulatory System blood is enclosed within vessels and is distinct from the interstitial fluid that bathes the cells. The blood is pumped by the heart through arteries, veins and capillaries. This type of system is found in most vertebrates including fish, amphibians, reptiles, birds and mammals.

Types of Closed Circulatory Systems

  1. Single Circulatory System –  This type of circulatory system is found in fish, and it consists of a single circuit of blood flow, where the heart pumps blood through the gills, where oxygen is extracted, and then to the rest of the body.
  2. Double Circulatory System – This type of circulatory system is found in mammals, birds, and reptiles, and it consists of two circuits of blood flow, one to the lungs (Pulmonary Circulation) and the other to the rest of the body (systemic circulation). The heart has two separate pumps, one for each circuit.

Double Circulatory System

Double Circulation is a type of Circulatory System where blood circulates through two separate loops, one for oxygenated blood and the other for deoxygenated blood. It is the most common type of Circulatory System found in mammals, including humans.The Double Circulation system is essential for providing an efficient method of blood flow to all organs of the body.

Also Check – What is Double Circulation in Human Beings Why is it Necessary ?

2 Loops of Double Circulation System

  1. Pulmonary Circulation
  2. Systemic circulation
Double Circulation System - 2 pathways
2 Loops of Double Circulation System – Pulmonary Circulation and Systemic Circulation

Pulmonary Circulation

The first loop of the Double Circulation system is the Pulmonary Circulation, which circulates deoxygenated blood from the heart to the lungs and back to the heart. Deoxygenated blood from the body is carried to the right atrium of the heart by the superior and inferior vena cava. From here, the blood is pumped to the right ventricle of the heart, which then pumps the blood to the lungs through the Pulmonary artery. In the lungs, carbon dioxide is removed and oxygen is taken up by the blood. The oxygenated blood then flows back to the heart through the Pulmonary veins which enter the left atrium.

Steps of Pulmonary Circulation

  1. Pulmonary circulation begins when the heart pumps deoxygenated blood from the right ventricle into the pulmonary artery.
  2. The pulmonary artery branches into smaller arteries, arterioles, and eventually into capillaries in the lungs.
  3. In the lungs, carbon dioxide diffuses from the deoxygenated blood in the capillaries into the air sacs (alveoli) of the lungs, where it is then exhaled.
  4. At the same time, oxygen from inhaled air diffuses from the air sacs into the capillaries, where it binds to hemoglobin in red blood cells and is transported back to the heart.
  5. The oxygenated blood then flows from the lungs through pulmonary veins, which merge together into the left atrium of the heart.
  6. From the left atrium, the oxygenated blood flows into the left ventricle of the heart.
  7. The left ventricle then pumps the oxygen-rich blood out into the aorta, starting the systemic circulation.

Important features of Pulmonary Circulation 

  1. Low Pressure: Pulmonary Circulation has a lower pressure than Systemic circulation, which allows for the exchange of gasses and nutrients between the lungs and the bloodstream.
  2. Short Distance: The distance between the heart and the lungs is relatively short, which allows for quick exchange of gasses.
  3. Capillary Network: The lungs have a dense capillary network, which provides a large surface area for gas exchange.

Systemic Circulation

The second loop of the Double Circulation system is the Systemic circulation .Systemic circulation is the movement of oxygen-rich blood from the heart to the body’s tissues and organs through the arteries, capillaries and veins Before returning deoxygenated blood back to the heart through the vena cava. 

Steps of Systemic Circulation

  1. The heart pumps oxygen-rich blood out of the left ventricle.
  2. The oxygen-rich blood flows into the aorta which is  the largest artery in the body.
  3. The blood then flows into smaller arteries and arterioles.
  4. The blood eventually reaches the capillaries which are tiny blood vessels only one cell thick.
  5. In the capillaries, oxygen and nutrients from the blood diffuse into the body’s cells while carbon dioxide and other waste products produced by the cells diffuse into the capillaries to be carried away.
  6. After passing through the capillaries, the blood flows into venules and veins.
  7. The blood eventually returns to the heart through the vena cava, the largest vein in the body.
  8. The deoxygenated blood enters the right atrium of the heart, completing the systemic circulation.

Important features of Systemic Circulation

  • Distribution of oxygen and nutrients-  Systemic circulation delivers oxygen and nutrients to the body’s tissues and organs. It  is essential for their proper function and survival.
  • Removal of waste products-  In addition to delivering oxygen and nutrients, systemic circulation also helps remove waste products such as carbon dioxide and other metabolic waste from the body’s tissues.
  • High pressure system-  Systemic circulation is a high-pressure system as the heart must pump blood through a network of arteries and arterioles that can resist blood flow. This helps ensure that oxygen and nutrients are delivered efficiently to all parts of the body.
  • Capillary beds – Capillaries are the smallest blood vessels in the body and are responsible for the exchange of oxygen, nutrients and waste products between the blood and the body’s tissues. Systemic circulation relies heavily on the vast network of capillary beds throughout the body to carry out this exchange.
  • Return of deoxygenated blood –  After delivering oxygen and nutrients to the body’s tissues, systemic circulation returns deoxygenated blood to the heart through the veins, which eventually merge into the vena cava. This allows the heart to pump this blood to the lungs for oxygenation and removal of carbon dioxide completing the double circulatory system.

Also Check – Difference between Double Circulation and Single Circulation

Double Circulation Flow Chart

Flow Chart of Double Circulation
Double Circulation Flow Chart

A double circulation flow chart Explains the two different circuits of blood flow in the human body –  Pulmonary Circulation and Systemic Circulation. 

The chart shows the flow of blood through the heart, lungs, and body, as well as the oxygenation and deoxygenation of blood in each circuit.

The flow chart typically starts with deoxygenated blood from the body entering the right atrium of the heart through the vena cava. From there, the blood is pumped into the right ventricle, which then pumps it out through the pulmonary artery and into the lungs for oxygenation. Oxygenated blood returns to the heart through the pulmonary veins, entering the left atrium and then the left ventricle which pumps the oxygenated blood out through the aorta and into the body’s tissues and organs for delivery of oxygen and nutrients. After oxygen and nutrients are delivered to the tissues and organs, deoxygenated blood returns to the heart through the veins to repeat the cycle.

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2 Types of Double Circulatory System

  1. Complete Double Circulation
  2. Incomplete Double Circulation

Complete Double Circulation

  • In this type of Double Circulation System, there are two separate circuits for the circulation of oxygenated and deoxygenated blood. 
  • The first circuit, known as the Pulmonary circuit, carries deoxygenated blood from the heart to the lungs where it receives oxygen and returns oxygenated blood back to the heart. 
  • The second circuit, known as the Systemic circuit, carries the oxygenated blood from the heart to the rest of the body. where it provides oxygen and nutrients to the tissues and organs and returns deoxygenated blood back to the heart.
  • Mammals, including humans, have a complete double Circulatory System. 
  • This system ensures that oxygen-rich blood is efficiently delivered to the body’s tissues while preventing oxygen-poor blood from mixing with oxygen-rich blood.

Incomplete Double Circulation

  • In this type of Double Circulation System there is only one ventricle in the heart that pumps blood to both the lungs and the rest of the body. This system is found in amphibians.
  • It’s important to note that Double Circulation is not the only type of Circulatory System found in animals. Some animals like insects and mollusks have an open Circulatory System where blood is not enclosed in vessels and is pumped directly into the body cavity. Others like some fish and reptiles, have a single circulation system, where the blood is pumped from the heart to the gills and then to the rest of the body before returning to the heart.

Also Check – Why is it necessary to separate Oxygenated and Deoxygenated Blood

Importance of Double Circulation

The Double Circulation system plays a crucial role in the survival and efficient functioning of complex organisms such as mammals. Here are some important reasons why Double Circulation is essential:

  1. Efficient transport of oxygen– The Double Circulation system allows for efficient transport of oxygen to all parts of the body. In Pulmonary Circulation, blood picks up oxygen from the lungs and delivers it to the heart. In Systemic circulation, the oxygen-rich blood is pumped to all parts of the body ensuring that each cell receives the necessary oxygen supply for cellular respiration.
  2. Efficient removal of carbon dioxide– The Double Circulation system also plays a crucial role in the efficient removal of carbon dioxide from the body. Carbon dioxide is produced as a byproduct of cellular respiration and it needs to be eliminated from the body to prevent the build-up of toxic levels. The blood carries carbon dioxide from the body tissues to the lungs where it is exhaled.
  3. Separation of oxygen-rich and oxygen-poor blood – The Double Circulation system also ensures the separation of oxygen-rich and oxygen-poor blood, preventing the mixing of the two types of blood. Mixing of oxygenated and deoxygenated blood can result in a decrease in oxygen-carrying capacity, which can have serious consequences for the body.
  4. Increased efficiency – The Double Circulation system is more efficient than a single circulation system, as it allows for greater control of blood flow and more precise delivery of oxygen and nutrients to the body’s tissues.
  5. Adaptability – The Double Circulatifishon system is highly adaptable, allowing for efficient regulation of blood flow depending on the body’s needs. For example, during exercise, the body’s demand for oxygen increases and the heart pumps faster to increase blood flow and deliver more oxygen to the muscles.

The Circulatory System

  • The circulatory system is the system of transportation in animals . 
  • It consists of your heart, blood, veins and arteries. It carries blood to every part of the body. 
  • The circulatory system delivers nutrients and oxygen to every cell in the body.
  • It also transports waste products such as carbon dioxide.
  • Animals have a transport system that delivers nutrients and oxygen to every part of the body.
  • It also carries waste products such as carbon dioxide to organs from where they can be removed from the body.

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Frequently asked questions on Double Circulation

What is Double Circulation and why is it important?

Answer – Double Circulation is a Circulatory System found in animals like mammals . In this system blood circulates through two separate loops, one for oxygenated blood and the other for deoxygenated blood. It is important because it allows for more efficient delivery of oxygen and nutrients to the body’s tissues and effective removal of waste products.

What are the two main types of Circulatory Systems found in animals?

Answer – The two main types of Circulatory Systems found in animals are Open Circulatory Systems and Closed Circulatory Systems.

What is the difference between Open and Closed Circulatory Systems?

Answer – In an Open Circulatory System, the CirculatoryFfluid is not always enclosed in vessels. In a Closed Circulatory System, blood is enclosed within vessels and is distinct from the interstitial fluid that bathes the cells.

What is the Single Circulatory System and where is it found?

Answer – The Single Circulatory System is a type of Circulatory System found in fish and it consists of a single circuit of blood flow. In this system the heart pumps blood through the gills, where oxygen is extracted and then to the rest of the body.

What is the Double Circulatory System and where is it found?

Answer – The Double Circulatory System is a type of Circulatory System found in mammals, birds and reptiles and it consists of two circuits of blood flow, one to the lungs (Pulmonary Circulation) and the other to the rest of the body (Systemic Circulation). The heart has two separate pumps, one for each circuit.

What are the two loops of the Double Circulatory System?

Answer – The two loops of the Double Circulatory System are Pulmonary Circulation and Systemic Circulation.

What is Pulmonary Circulation and what is its function?

Answer – Pulmonary Circulation is the first loop of the Double Circulatory System, which circulates deoxygenated blood from the heart to the lungs and back to the heart. Its function is to oxygenate the blood and remove carbon dioxide.

What are the important features of Pulmonary Circulation?

Answer – The important features of Pulmonary Circulation are low pressure, short distance between the heart and lungs and a dense capillary network in the lungs that provides a large surface area for gas exchange.

What is Systemic Circulation?

Answer – Systemic Circulation is the second loop of the Double Circulation system. It is the movement of oxygen-rich blood from the heart to the body’s tissues and organs through the arteries, capillaries and veins before returning deoxygenated blood back to the heart through the vena cava.

What are the steps involved in Systemic Circulation?

Answer – The steps involved in Systemic Circulation are –

  • The heart pumps oxygen-rich blood out of the left ventricle.
  • The oxygen-rich blood flows into the Aorta, the blood then flows into smaller arteries and arterioles.
  • The blood eventually reaches the capillaries, where oxygen and nutrients diffuse into the body’s cells, carbon dioxide and other waste products diffuse into the capillaries to be carried away.
  • After passing through the capillaries, the blood flows into venules and veins and eventually returns to the heart through the Vena Cava.
What is the importance of Systemic Circulation?

Answer – Systemic Circulation is important because it delivers oxygen and nutrients to the body’s tissues and organs. It removes waste products such as carbon dioxide and other metabolic waste from the body’s tissues. It is a high-pressure system that ensures efficient delivery of oxygen and nutrients to all parts of the body.

What are Capillary beds and how do they contribute to Systemic Circulation?

Answer – Capillary beds are the smallest blood vessels in the body and are responsible for the exchange of oxygen, nutrients and waste products between the blood and the body’s tissues. Systemic Circulation relies heavily on the vast network of capillary beds throughout the body to carry out this exchange.

What is the role of the vena cava in Systemic Circulation?

Answer – The vena cava is the largest vein in the body and is responsible for returning deoxygenated blood back to the heart after Systemic Circulation is complete. This allows the heart to pump this blood to the lungs for oxygenation and removal of carbon dioxide, completing the Double Circulatory System.

What are the two types of Double Circulatory Systems?

Answer – The two types of Double Circulatory Systems are complete Double Circulation and incomplete Double Circulation. Complete Double Circulation is found in mammals and ensures that oxygen-rich blood is efficiently delivered to the body’s tissues while preventing oxygen-poor blood from mixing with oxygen-rich blood. Incomplete Double Circulation is found in amphibians and has only one ventricle in the heart that pumps blood to both the lungs and the rest of the body.

What is the Importance of Double Circulation?

Answer – The Double Circulation system plays a crucial role in the survival and efficient functioning of complex organisms such as mammals. It allows for efficient transport of oxygen to all parts of the body, ensures that oxygen-rich blood is efficiently delivered to the body’s tissues while preventing oxygen-poor blood from mixing with oxygen-rich blood and provides a high-pressure system that ensures efficient delivery of oxygen and nutrients to all parts of the body.