Blood

• Blood is a red coloured fluid which circulates in the Human Body.
• Blood is a complex fluid that circulates through our bodies delivering oxygen and nutrients to our cells, removing waste products and fighting off infections and diseases.
• Blood is red because of a pigment called Haemoglobin in its Red Blood Cells. 
• Blood is a connective tissue. All the Blood Cells are made in the bone marrow from the cells called stem cells.
• The Circulatory System responsible for transporting Blood throughout the body  is one of the most critical systems in the Human Body. 
• Without Blood our organs and tissues would not receive the oxygen and nutrients they need to function correctly and our immune system would not be able to defend us against harmful pathogens.

Composition of Blood 

Blood consists of a variety of components each with its unique role and function. Understanding the composition of Blood is crucial for maintaining optimal health and preventing various diseases and disorders.

4 Main Components of Blood are 

1. Plasma
2. Red Blood Corpuscles(RBCS)
3. White Blood Corpuscles(WBCS) 
4. Platelets.

Plasma

What is Plasma ?

• The  fluid part of Blood is called Plasma. It makes up about 55% of its total volume of the Blood .
• Plasma is a yellowish liquid that contains water, proteins, nutrients, hormones, waste products and other substances necessary for the proper functioning of the body.
• Plasma contains about 90 percent water. The remaining 10% consists of various proteins, including albumin, globulins and fibrinogen as well as hormones, enzymes, vitamins, minerals and waste products. 
• Red Blood Cells, White Blood Cells and Platelets are immersed in this liquid called Plasma.

Also Check – Composition of Lymph

Also Check – Components Of Blood

Functions of Plasma 

• Plasma has several essential functions in the body. It helps to transport nutrients such as glucose, amino acids and lipids from the digestive system to the body’s tissues. 
• Albumin is the most abundant protein in Plasma and helps to regulate the movement of fluids between the Blood and tissues. Globulins are a group of proteins that include antibodies which help to protect the body against infections. Fibrinogen is a protein that plays a crucial role in Blood clotting.
• Plasma also carries waste products such as carbon dioxide and urea  from the tissues to the organs responsible for their elimination such as the lungs and kidneys.
• Plasma also plays an important role in Blood circulation by helping to maintain the proper balance of fluids and electrolytes in the body.
• Plasma helps to regulate Blood pressure and ensures that Blood flows smoothly through the Blood vessels.

Also Check – 12 Important Functions of Blood Plasma

Also Check – Describe the Flow of Blood through the Heart of Human Beings

Red Blood Cells (RBC’s)

What are Red Blood Cells (RBCs) ? 

• Red Blood Cells also known as erythrocytes are the most abundant cells in our Blood. 
• Haemoglobin is a  protein that binds with oxygen molecules and gives Blood its characteristic red colour.
• Each Red Blood Cell contains approximately 270 million molecules of Haemoglobin which allows it to carry a large amount of oxygen.
• They are disc-shaped cells that are approximately 7.5 micrometres in diameter and have a concave shape that helps them to travel through the Blood vessels smoothly.
• Red Blood Cells have a thin flexible membrane that allows them to change shape as they move through narrow Blood vessels. 
• RBCs concave shape increases their surface area which enables them to absorb and release oxygen more efficiently.
• Red Blood Cells are produced in the bone marrow and have a lifespan of approximately 120 days. After this time they are removed from circulation and broken down by the spleen and liver. New Red Blood Cells are continuously produced in the bone marrow to replace the old ones.
• Factors that can affect the production and lifespan of Red Blood Cells are iron deficiency, vitamin deficiency and certain diseases such as sickle cell anaemia. Maintaining a healthy diet rich in iron, vitamins  and other nutrients is essential for the production of healthy Red Blood Cells.

Functions of Red Blood Cell (RBCs)

• The Main function of Red Blood Cells is to transport oxygen from the lungs to the body’s tissues and organs. The structure of Red Blood Cells is highly specialised to facilitate their function. 

White Blood Cells (WBC’s)

What are White Blood Cells(WBCs) ?

• White Blood Cells fight infection and protect us from diseases .
• White  Blood Cells help to fight against germs and other foreign bodies which causes diseases.
•  White Blood Cells engulf  the Pathogens which cause diseases.
• White Blood Cells provide immunity to the Human Body by making ‘antibodies’ to fight  against infection .      
• White Blood Cells are produced in the bone marrow and are involved in the body’s immune response to infections and diseases.    
• White Blood Cells are either spherical in shape or irregular in shape.
•  All the White Blood Cells have a nucleus though the shape of the nucleus is different in different  types of White Blood Cells. 
• White Blood Cells (WBC) in the Blood are much smaller in number than Red Blood Cells.
• White Blood Cells also known as leukocytes are cells that play an important role in the body’s immune system by fighting off infections and diseases.
• Unlike Red Blood Cells White Blood Cells have a nucleus and do not contain Haemoglobin.
• The number and type of White Blood Cells in the body can vary depending on various factors such as age, gender and health status.

White Blood Cells (WBCs ) – Types and Functions 

There are five main types of White Blood Cells each with a specific function in the immune system which are as follows – 

1. Neutrophils 
2. Lymphocytes
3. Monocytes
4. Eosinophils
5. Basophils

Neutrophils 

•  Neutrophils are the most abundant type of White Blood Cell and are the first to arrive at the site of an infection. 
• They engulf and destroy bacteria and other foreign invaders.

Lymphocytes

• Lymphocytes are another type of White Blood Cell that includes B cells, T cells and natural killer cells. 
• B cells produce antibodies that can recognize and neutralise specific pathogens. 
• T cells help to destroy infected cells and coordinate the immune response. 
• Natural killer cells can recognize and kill infected cells without the need for antibodies.

Monocytes

• Monocytes are large White Blood Cells that can differentiate into macrophages and dendritic cells. 
• Macrophages engulf and digest foreign invaders while dendritic cells help to present antigens to other cells in the immune system.

Eosinophils

• Eosinophils are White Blood Cells that help to fight off parasites and allergic reactions. 
• They release toxic substances that can kill parasites and help to reduce inflammation.

Basophils

• Basophils are the least common type of White Blood Cell and play a role in allergic reactions. They release histamine, which causes Blood vessels to dilate and increases inflammation.

Also Check – Functions of Blood

Platelets

Also Check – Maintenance by Platelets (Blood Clotting) 

What are Platelets ?

• Platelets are also known as thrombocytes. 
• They are the tiny fragments of special cells that circulate in the Blood. 
• Platelets do not have nuclei. 
• Platelets play a critical role in the process of Blood clotting which is necessary to prevent excessive bleeding after an injury.
• Platelets are produced in the bone marrow and have a lifespan of approximately 7-10 days.
• Platelets are constantly being produced and removed from circulation ensuring that there are always enough Platelets available to respond to an injury.
• Certain medical conditions can affect the production and function of Platelets such as thrombocytopenia (low Platelet count) or thrombocythemia (high Platelet count). These conditions can increase the risk of bleeding or clotting and require medical attention.

Also Check – What will happen if Platelets were Absent in the Blood

Functions of Platelets 

• When a Blood vessel is damaged Platelets are activated and rush to the site of the injury. They  begin to stick to the damaged area of the Blood vessel and to each other forming a plug that helps to stop the bleeding.
• Platelets help in the coagulation of Blood (or clotting of Blood) in a cut or wound. For example when a cut or wound starts bleeding, then Platelets help clot the Blood (make the Blood semi-solid) due to which further bleeding stops 
• Platelets also release chemicals that help to activate other clotting factors in the Blood. 
• These factors work together to form a fibrin clot which further reinforces the Platelet plug and seals off the wound.

Also Check – 9 Important Function of the Platelets

Frequently Asked Question on Blood Composition

What is Blood and what is its function in the Human Body?

Answer- Blood is a complex fluid that circulates through our bodies delivering oxygen and nutrients to our cells, removing waste products and fighting off infections and diseases. Its function is critical for maintaining optimal health and preventing various diseases and disorders.

Why is Blood red in colour?

Answer- Blood is red because of a pigment called Haemoglobin in its Red Blood Cells.

What is the Composition of Blood?

Answer- Blood consists of a variety of components, including Plasma, Red Blood Corpuscles (RBCs), White Blood Corpuscles (WBCs) and Platelets.

What is Plasma and what are its functions in the body?

Answer- Plasma is the fluid part of Blood that makes up about 55% of its total volume. It contains water, proteins, nutrients, hormones, waste products and other substances necessary for the proper functioning of the body. Its functions include transporting nutrients, carrying waste products, regulating Blood pressure and maintaining the proper balance of fluids and electrolytes in the body.

What are Red Blood Cells (RBCs) and what are their functions?

Answer- Red Blood Cells are the most abundant cells in our Blood and contain Haemoglobin that allows them to carry a large amount of oxygen. Their main function is to transport oxygen from the lungs to the body’s tissues and organs.

How are Red Blood Cells produced and what factors can affect their production?

Answer- Red Blood Cells are produced in the bone marrow from stem cells. Factors that can affect their production and lifespan include iron deficiency, vitamin deficiency and certain diseases such as sickle cell anaemia. Maintaining a healthy diet rich in iron, vitamins and other nutrients is essential for the production of healthy Red Blood Cells.

What is the lifespan of Red Blood Cells and how are they removed from circulation?

Answer- Red Blood Cells have a lifespan of approximately 120 days. After this time, they are removed from circulation and broken down by the spleen and liver. New Red Blood Cells are continuously produced in the bone marrow to replace the old ones.

What are White Blood Cells (WBCs) and what is their function in the body?

Answer- White Blood Cells are cells that play an important role in the body’s immune system by fighting off infections and diseases. They protect us from diseases by fighting against germs and other foreign bodies that cause diseases. They engulf Pathogens which cause diseases and provide immunity to the Human Body by making antibodies to fight against infection.

Where are White Blood Cells produced and what is their shape?

Answer- White Blood Cells are produced in the bone marrow and can be spherical or irregular in shape. All the White Blood Cells have a nucleus, though the shape of the nucleus is different in different types of White Blood Cells.

What is the difference between Red Blood Cells and White Blood Cells?

Answer- Unlike Red Blood Cells, White Blood Cells have a nucleus and do not contain haemoglobin. White Blood Cells are much smaller in number than Red Blood Cells.

What are the five main types of White Blood Cells and what are their functions?

Answer- The five main types of White Blood Cells are Neutrophils, Lymphocytes, Monocytes, Eosinophils and Basophils. Neutrophils are the most abundant type of White Blood Cell and are the first to arrive at the site of an infection. Lymphocytes include B cells, T cells and natural killer cells. they play a role in recognizing and neutralising specific Pathogens, destroying infected cells and coordinating the immune response. Monocytes can differentiate into macrophages and dendritic cells that engulf and digest foreign invaders and present antigens to other cells in the immune system. Eosinophils help fight off parasites and allergic reactions, while Basophils play a role in allergic reactions and release histamine that increases inflammation.

What are Platelets and what is their function in the body?

Answer- Platelets are tiny fragments of special cells that circulate in the Blood and play a critical role in the process of Blood clotting. Blood clotting is necessary to prevent excessive bleeding after an injury. They are produced in the bone marrow and have a lifespan of approximately 7-10 days. When a Blood vessel is damaged, Platelets rush to the site of the injury and begin to stick to the damaged area of the Blood vessel and to each other, forming a plug that helps to stop the bleeding. They also release chemicals that help to activate other clotting factors in the Blood that work together to form a fibrin clot that further reinforces the Platelet plug and seals off the wound.

What are the medical conditions that can affect the production and function of Platelets?

Answer- Certain medical conditions, such as thrombocytopenia (low Platelet count) or thrombocythemia (high Platelet count), can affect the production and function of Platelets. These conditions can increase the risk of bleeding or clotting and require medical attention.

How long do Platelets typically live in the body?

Answer- Platelets typically have a lifespan of approximately 7-10 days.

How do Platelets help in the coagulation of Blood?

Answer- When a cut or wound starts bleeding, Platelets help clot the Blood (make the Blood semi-solid), due to which further bleeding stops. They help in the coagulation of Blood by sticking to the damaged area of the Blood vessel and to each other, forming a plug that helps to stop the bleeding. Platelets also release chemicals that help to activate other clotting factors in the Blood that work together to form a fibrin clot that further reinforces the Platelet plug and seals off the wound.