The Human Circulatory System is a complex network of Arteries, Veins and Capillaries that is responsible for the transportation of Blood throughout the body. The Heart acts as a pump, pushing Blood through the Circulatory System to deliver oxygen, nutrients and hormones to various parts of the body, while also collecting metabolic waste and toxins from the cells and tissues for elimination.
Table of Contents
Human Circulatory System – Diagram
Organs of the Human Circulatory System
The Circulatory System is a complex network of organs, Blood Vessels and fluids that work together to Transport Oxygen, nutrients, Hormones and waste products throughout the body.
Following are the vital organs of Human Circulatory System
The Heart
Structure of The Heart-
The Heart is a muscular organ located in the chest, between the Lungs. It is roughly the size of a fist and is divided into four chambers- The Right Atrium, Right Ventricle, Left Atrium and Left Ventricle. The Heart is surrounded by a sac called the Pericardium.It contains a small amount of fluid to help reduce friction as The Heart beats.
Function of The Heart-
The Heart is responsible for pumping Blood throughout the body. The right side of The Heart pumps Deoxygenated Blood to the Lungs to be Oxygenated while the left side pumps Oxygenated Blood to the rest of the body.
Valves-
The Heart has four Valves that ensure that Blood flows in the correct direction. The tricuspid Valve is located between The Right Atrium and ventricle, while the mitral Valve is located betweenThe Left Atrium and ventricle. The Pulmonary Valve is located at the exit of the Right Ventricle and opens to allow Blood to flow to the Lungs, while the Aortic Valve is located at the exit of the Left Ventricle and opens to allow Blood to flow to the rest of the body.
Also Check – Heart Valves- Types, Location, Structure and Functions
Also Check – Heart Valve Problems and Causes
How The Heart works-
The Heart works as a pump to circulate Blood throughout the body. Deoxygenated Blood from the body returns to The Right Atrium and is pumped into the Right Ventricle. From there, the Right Ventricle pumps the Blood through the Pulmonary Valve and into the Lungs, where it is Oxygenated. Oxygenated Blood returns toThe Left Atrium and is pumped into the Left Ventricle. From there, the Left Ventricle pumps the Blood through the Aortic Valve and into the Aorta. It carries the Blood to the rest of the body. The Heart beats in a coordinated rhythm, with electrical signals that originate in the Sinoatrial Node (SA node) in The Right Atrium, spreading throughout The Heart to trigger contractions and ensure proper Blood flow.
Also Check – Describe the Flow of Blood through the Heart of Human Beings
Blood Vessels
Blood Vessels are an integral part of the Circulatory System, responsible for the transportation of Blood throughout the body. There are three types of Blood Vessels in the Circulatory System-
Arteries
Arteries are vessels that carry oxygen-rich Blood away from The Heart to various parts of the body. They have thick muscular walls that help maintain Blood pressure and flow. The largest Artery in the body is the Aorta. It branches off into smaller Arteries throughout the body. Arteries also have smaller branches called Arterioles . It regulates Blood flow to specific organs.
Also Check – Why Do Arteries Have Thick Elastic Walls ?
Veins
Veins are vessels that carry Deoxygenated Blood back to The Heart from the body’s organs and tissues. They have thinner walls than Arteries and rely on the contraction of muscles and Valves to move Blood back to The Heart. The largest Vein in the body is the vena cava, which receives Blood from the lower half of the body and the upper half of the body through two separate branches.
Also Check – 15 Important Differences Between Arteries and Veins
Capillaries
Capillaries are the smallest and thinnest Blood Vessels in the Circulatory System, responsible for exchanging nutrients, oxygen and waste products between the Blood and body tissues. Capillaries are so small that red Blood cells must pass through them single-file. They are located throughout the body and form a network that connects Arterioles to venules.
Also Check- 8 Difference Between Arteries , Veins and Capillaries
Functions of Blood Vessels
The functions of Blood Vessels are to transport Blood throughout the body, regulate Blood pressure and control Blood flow. Arteries and Arterioles are responsible for delivering Oxygenated Blood to the body’s organs and tissues, while Veins and venules transport Deoxygenated Blood back to The Heart. Capillaries facilitate the exchange of nutrients, gases and waste products between the Blood and body tissues.
Blood Vessels work by using the force of The Heart’s contractions to propel Blood through the Arteries and Arterioles. The Capillaries facilitate the exchange of nutrients, oxygen and waste products between the Blood and tissues. Finally, the Veins and venules use muscle contractions and Valves to move Deoxygenated Blood back to The Heart. This continuous cycle of Blood flow is essential for maintaining proper bodily function.
Also Check – Types and Functions of Blood Vessels
Blood
Blood is a vital component of the Circulatory System, transporting oxygen, nutrients, hormones and other essential substances throughout the body. It also plays a key role in regulating body temperature, pH levels and electrolyte balance, as well as protecting the body against infections and foreign invaders.
Composition of Blood
Blood is composed of two main components- Plasma and Blood cells. Plasma is a yellowish fluid that makes up about 55% of Blood volume. It consists of water, proteins, electrolytes, hormones and other molecules. Blood cells make up the remaining 45% of Blood volume and are categorised into three main types- red Blood cells (erythrocytes), white Blood cells (leukocytes) and platelets (thrombocytes). Red Blood cells transport oxygen to body tissues, white Blood cells play a key role in the immune system by fighting infections and platelets are involved in Blood clotting.
Also Check – Blood Coagulation (Blood Clotting)
Functions of Blood
The functions of Blood can be broadly categorised into transportation, regulation and protection.
Transportation
Blood transports oxygen and nutrients to body tissues and removes carbon dioxide and waste products from the body. It also carries hormones, enzymes and other molecules to different parts of the body.
Regulation
Blood helps regulate body temperature by distributing heat throughout the body. It also plays a role in maintaining pH levels and electrolyte balance. For example, the bicarbonate buffer system in the Blood helps to regulate pH levels in the body.
Protection
Blood plays a crucial role in protecting the body against infections and foreign invaders. White Blood cells, such as neutrophils and Lymphocytes, are involved in fighting infections, while platelets are involved in Blood clotting to prevent excessive bleeding.Plasma contains antibodies, which are proteins that recognize and neutralise foreign invaders such as viruses and bacteria.
Also Check – 10 Important Functions of Blood
The Lymphatic System
The Lymphatic System is a vital component of the Circulatory System that helps to maintain the balance of fluids in the body and support the immune system. It comprises Lymphatic vessels, Lymph nodes and Lymphoid organs, such as the spleen and thymus gland.
Lymphatic vessels are a network of thin tubes that branch out into various parts of the body, similar to the Blood Vessels. These vessels carry a fluid called Lymph, which is a clear, watery fluid containing white Blood cells, proteins and fats. Lymphatic vessels collect the excess fluid that leaks from the Blood Vessels and return it to the Circulatory System to maintain fluid balance.
Lymph nodes are small, bean-shaped structures located throughout the body, usually in groups. They are responsible for filtering Lymph, removing foreign substances like bacteria, viruses and cancer cells and activating immune responses.
The Lymphatic system works in conjunction with the Circulatory System to ensure the proper functioning of the immune system. Lymphatic vessels help to transport white Blood cells to the Lymph nodes, where they can detect and attack any harmful substances that enter the body. The Lymphatic system also plays a role in absorbing fats from the digestive system and transporting them to the Circulatory System for use by the body.
Also Check – 9 Important function of Lymphatic System
Also Check – Key Organs of the Lymphatic System: Functions and Locations.
How the Circulatory System Works ?
- Blood enters The Heart through two large Veins, The Superior Vena Cava and The Inferior Vena Cava. The Blood is Deoxygenated and low in nutrients.
- The Blood then flows into The Right Atrium.It contracts to push the Blood into the Right Ventricle.
- The Right Ventricle contracts to pump the Blood through the Pulmonary Artery and into the Lungs.
- In the Lungs, the Blood picks up oxygen and releases carbon dioxide, becoming Oxygenated and high in nutrients.
- The Oxygenated Blood then flows intoThe Left Atrium through the Pulmonary Vein.
- The Left Atrium contracts to push the Oxygenated Blood into the Left Ventricle.
- The Left Ventricle contracts to pump the Oxygenated Blood out of The Heart and into the Aorta, the largest Artery in the body.
- The Aorta branches out into smaller Arteries that carry the Oxygenated Blood to all parts of the body.
- As the Oxygenated Blood reaches the Capillaries, it releases oxygen and nutrients to the body’s cells and tissues.
- The Capillaries then collect carbon dioxide and other waste products from the cells and tissues.
- The Deoxygenated Blood then flows into the smallest Veins, called venules and then into larger Veins.
- The Veins carry the Deoxygenated Blood back to The Heart, where the process starts all over again.
Also Check – Fascinating Facts about the Circulatory System
Features of the Circulatory System
Following features of the Circulatory System that are important to understand-
- Components- The Human Circulatory System consists of four main components- Blood, Heart, Blood Vessels and Lymph. Blood is a fluid that carries oxygen, nutrients and waste products throughout the body. The Heart is a muscular organ that pumps Blood through the Blood Vessels. Blood Vessels are tubes that transport Blood to and from The Heart and other parts of the body. The Lymphatic system is a network of vessels and tissues that help remove waste and fight infection.
- Double Circulation- The Human Circulatory System has a unique structure known as Double Circulation. This means that Blood circulates through two loops – one for Oxygenated Blood and another for Deoxygenated Blood. The Pulmonary Circuit carries Deoxygenated Blood from The Heart to the Lungs, where it picks up oxygen and returns to The Heart. The Systemic Circuit carries Oxygenated Blood from The Heart to the rest of the body and returns Deoxygenated Blood back to The Heart.
- Heart Chambers- The Human Heart consists of four chambers – two ventricles and two auricles. The Right Atrium and ventricle pump Deoxygenated Blood to the Lungs, whileThe Left Atrium and ventricle pump Oxygenated Blood to the rest of the body.
- Blood Vessels- The Circulatory System has a vast network of Blood Vessels, including Arteries, Veins and Capillaries. Arteries carry Oxygenated Blood away from The Heart, while Veins carry Deoxygenated Blood back to The Heart. Capillaries are small, thin-walled vessels that allow for the exchange of nutrients and waste products between the Blood and tissues.
- Functions of Blood Vessels- Blood Vessels have several important functions in the Circulatory System. They transport oxygen and nutrients to all parts of the body and they collect metabolic waste products to be expelled from the body. They also play a role in regulating Blood pressure and body temperature.
- Length- The Human Circulatory System is incredibly long, with the Blood Vessels, if laid out end to end, spanning a total distance of approximately 100,000 kilometres. This means that the Blood Vessels could circle the Earth’s equator roughly eight times.
Also Check – Why is it necessary to separate Oxygenated and Deoxygenated Blood ?
Double Circulation
Double Circulation is a concept that describes how Blood flows through two separate circuits in the Circulatory System. In the Human Circulatory System, the two circuits are
- The Pulmonary Circuit
- The Systemic Circuit
The Pulmonary Circuit-
The Pulmonary Circuit involves the circulation of Blood between The Heart and the Lungs. Deoxygenated Blood from the body returns to The Right Atrium of The Heart and then is pumped into the Right Ventricle. From there, it is pumped through the Pulmonary Valve and into the Pulmonary Artery, which carries the Blood to the Lungs. In the Lungs, the Blood is Oxygenated and then returns to The Heart through the Pulmonary Veins. The Oxygenated Blood entersThe Left Atrium and is then pumped into the Left Ventricle.
The Systemic Circuit-
The Systemic Circuit involves the circulation of Oxygenated Blood throughout the rest of the body. Once the Left Ventricle pumps Oxygenated Blood into the Aorta, it is distributed to the rest of the body through a network of Arteries, Arterioles, Capillaries, venules and Veins. The oxygen in the Blood is utilised by the body’s cells and carbon dioxide and other metabolic waste products are returned to The Heart for elimination through the Pulmonary Circuit.
Role of Pulmonary and Systemic Circuits in Circulation
The roles of the Pulmonary and Systemic Circuits are crucial to the proper functioning of the Circulatory System. The Pulmonary Circuit is responsible for oxygenating the Blood and removing carbon dioxide, while the Systemic Circuit delivers Oxygenated Blood to the body’s cells and tissues and removes waste products.
Also Check – Difference between Double Circulation and Single Circulation
Functions of the Circulatory System
- Transportation of oxygen- The Circulatory System is responsible for transporting oxygen from the Lungs to the rest of the body’s tissues and organs, where it is used for cellular respiration.
- Transportation of nutrients- The Circulatory System is also responsible for transporting nutrients, such as glucose and amino acids, from the digestive system to the body’s tissues and organs.
- Transportation of hormones- Hormones are produced by various glands and transported by the Circulatory System to their target organs.
- Removal of waste products- The Circulatory System plays a crucial role in removing waste products, such as carbon dioxide and urea, from the body’s tissues and organs. These waste products are then transported to the Lungs and kidneys, respectively, for elimination.
- Regulation of body temperature- The Circulatory System helps regulate body temperature by transporting heat away from the body’s core and toward the skin’s surface, where it can be dissipated.
- Regulation of pH- The Circulatory System helps maintain the body’s pH balance by transporting acids and bases to and from the Lungs and kidneys for elimination.
- Immune function- The Circulatory System includes the Lymphatic system.It plays a crucial role in the body’s immune function. The Lymphatic system helps to remove pathogens and foreign substances from the body, preventing infection and disease.
- Blood clotting- The Circulatory System is also responsible for Blood clotting. It helps prevent excessive bleeding from injuries.
Frequently Asked Questions of Human Circulatory System
What is the Human Circulatory System?
Answer- The Human Circulatory System is a complex network of Arteries, Veins and Capillaries that is responsible for the transportation of Blood throughout the body. It is responsible for delivering oxygen, nutrients and hormones to various parts of the body, while also collecting metabolic waste and toxins from the cells and tissues for elimination.
What are the vital organs of the Human Circulatory System?
Answer- The vital organs of the Human Circulatory System include The Heart, Blood Vessels and lymphatic system.
What is the Structure of The Heart?
Answer- The Heart is a muscular organ located in the chest, between the Lungs. It is roughly the size of a fist and is divided into four chambers – The Right Atrium, Right Ventricle, Left Atrium and Left Ventricle. The Heart is surrounded by a sac called the Pericardium.It contains a small amount of fluid to help reduce friction as The Heart beats.
What is the function of The Heart?
Answer- The Heart is responsible for pumping Blood throughout the body. The right side of The Heart pumps deoxygenated Blood to the Lungs to be oxygenated, while the left side pumps oxygenated Blood to the rest of the body. Readmore…
What are the four Valves of The Heart?
Answer- The four Valves of The Heart include the tricuspid Valve, located between The Right Atrium and ventricle, the mitral Valve located betweenThe Left Atrium and ventricle, the pulmonary Valve located at the exit of the Right Ventricle and the Aortic Valve located at the exit of the Left Ventricle.
How does The Heart work?
Answer- The Heart works as a pump to circulate Blood throughout the body. Deoxygenated Blood from the body returns to The Right Atrium and is pumped into the Right Ventricle. From there, the Right Ventricle pumps the Blood through the pulmonary Valve and into the Lungs, where it is oxygenated. Oxygenated Blood returns toThe Left Atrium and is pumped into the Left Ventricle. From there, the Left Ventricle pumps the Blood through the Aortic Valve and into the Aorta. It carries the Blood to the rest of the body. The Heart beats in a coordinated rhythm, with electrical signals that originate in the Sinoatrial Node (SA node) in The Right Atrium, spreading throughout The Heart to trigger contractions and ensure proper Blood flow.
What are the three types of Blood Vessels in the circulatory system?
Answer- The three types of Blood Vessels in the circulatory system are Arteries, Veins and Capillaries.
What are Arteries?
Answer- Arteries are vessels that carry oxygen-rich Blood away from The Heart to various parts of the body. They have thick muscular walls that help maintain Blood pressure and flow.
What are Veins?
Answer- Veins are vessels that carry deoxygenated Blood back to The Heart from the body’s organs and tissues. They have thinner walls than Arteries and rely on the contraction of muscles and Valves to move Blood back to The Heart.
What are Capillaries?
Answer- Capillaries are the smallest and thinnest Blood Vessels in the circulatory system, responsible for exchanging nutrients, oxygen and waste products between the Blood and body tissues. Capillaries are so small that red Blood cells must pass through them single-file.
What are the functions of Blood Vessels?
Answer- The functions of Blood Vessels are to transport Blood throughout the body, regulate Blood pressure and control Blood flow. Arteries and arterioles are responsible for delivering oxygenated Blood to the body’s organs and tissues, while Veins and venules transport deoxygenated Blood back to The Heart. Capillaries facilitate the exchange
What are the two main components of Blood and what is the percentage of each in Blood volume?
Answer- Blood is composed of two main components, plasma and Blood cells. Plasma makes up about 55% of Blood volume, while Blood cells make up the remaining 45%.
What are the three main types of Blood cells and what are their functions?
Answer- The three main types of Blood cells are red Blood cells (erythrocytes), white Blood cells (leukocytes) and platelets (thrombocytes). Red Blood cells transport oxygen to body tissues, white Blood cells play a key role in the immune system by fighting infections and platelets are involved in Blood clotting.
What are the functions of Blood and how can they be categorised?
Answer- The functions of Blood can be broadly categorised into transportation, regulation and protection. Blood transports oxygen and nutrients to body tissues, removes carbon dioxide and waste products from the body, carries hormones, enzymes and other molecules to different parts of the body, helps regulate body temperature, pH levels and electrolyte balance and plays a crucial role in protecting the body against infections and foreign invaders.
What is the lymphatic system and what are its components?
Answer- The lymphatic system is a vital component of the circulatory system that helps to maintain the balance of fluids in the body and support the immune system. It comprises lymphatic vessels, lymph nodes and lymphoid organs such as the spleen and thymus gland.
What are the functions of the lymphatic system and how does it work with the circulatory system?
Answer- The lymphatic system helps to transport white Blood cells to the lymph nodes, where they can detect and attack any harmful substances that enter the body. It also plays a role in absorbing fats from the digestive system and transporting them to the circulatory system for use by the body. The lymphatic system works in conjunction with the circulatory system to ensure the proper functioning of the immune system.
What are the features of the circulatory system that are important to understand?
Answer- Some important features of the circulatory system include its four main components (Blood, heart, Blood Vessels and lymph), its unique structure of double circulation, its heart chambers (four chambers), its vast network of Blood Vessels (Arteries, Veins and Capillaries), its important functions in regulating Blood pressure, body temperature and metabolic waste products and its incredible length (Blood Vessels if laid out end to end would span a total distance of approximately 100,000 kilometres).
Also Check – What’s Systolic and Diastolic Blood Pressure?
What is double circulation and what are the two circuits involved in it?
Answer- Double circulation is a concept that describes how Blood flows through two separate circuits in the circulatory system. In the Human Circulatory System, the two circuits are the pulmonary circuit and the systemic circuit. The pulmonary circuit carries deoxygenated Blood from The Heart to the Lungs, where it picks up oxygen and returns to The Heart. The systemic circuit carries oxygenated Blood from The Heart to the rest of the body and returns deoxygenated Blood back to The Heart.
Also Check – What is Double Circulation in Human Beings Why is it Necessary ?
What are the main functions of the Circulatory System?
Answer- The main functions of the Circulatory System are transportation of oxygen, nutrients and hormones, removal of waste products, regulation of body temperature and pH balance, immune function and Blood clotting.
What is the role of the Lymphatic system in the Circulatory System?
Answer- The Lymphatic system is responsible for immune function and plays a crucial role in removing pathogens and foreign substances from the body, preventing infection and disease.
How does the Circulatory System regulate body temperature?
Answer- The Circulatory System helps regulate body temperature by transporting heat away from the body’s core and toward the skin’s surface, where it can be dissipated.
What is the process by which Oxygenated Blood is transported to the body’s cells and tissues?
Answer- The Oxygenated Blood flows from the Left Ventricle through the Aorta. It branches out into smaller Arteries that carry the Oxygenated Blood to all parts of the body. As the Oxygenated Blood reaches the Capillaries, it releases oxygen and nutrients to the body’s cells and tissues.
How does the Circulatory System remove waste products from the body?
Answer- The Circulatory System plays a crucial role in removing waste products, such as carbon dioxide and urea, from the body’s tissues and organs. These waste products are then transported to the Lungs and kidneys, respectively, for elimination.
What is the process by which Deoxygenated Blood is transported back to The Heart?
Answer- The Deoxygenated Blood flows into the smallest Veins, called venules and then into larger Veins. The Veins carry the Deoxygenated Blood back to The Heart, where the process starts all over again.
How does the Circulatory System maintain the body’s pH balance?
Answer- The Circulatory System helps maintain the body’s pH balance by transporting acids and bases to and from the Lungs and kidneys for elimination.
What is the role of Blood clotting in the Circulatory System?
Answer- Blood clotting is responsible for preventing excessive bleeding from injuries. Read in details …
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