Human Blood RRB NTPC Notes 2025, Functions, Components

Understanding human blood is important for various competitive exams, especially the RRB NTPC 2025 exam. Questions related to blood, its components, and functions are often asked in the General Awareness section. This article provides complete, concise, and exam-relevant notes on Human Blood.

Human Blood

Blood is a red-colored fluid connective tissue that circulates in our body. It performs several vital functions like transporting oxygen, nutrients, hormones, and removing waste materials from the body.

• Average blood volume in adults: ~5 to 6 liters
• pH of blood: 7.35 – 7.45 (slightly alkaline)

Functions of Blood

Blood performs several critical functions such as transporting oxygen, carbon dioxide, nutrients, hormones, and waste materials. It helps regulate body temperature, pH levels, and water content. Additionally, it defends the body against infections and helps in blood clotting to prevent excessive bleeding. Blood plays a crucial role in:

• Transport: Oxygen, carbon dioxide, nutrients, hormones, and waste.
• Protection: Fights infections via white blood cells and antibodies.
• Regulation: Maintains temperature, pH balance, and water content.

Components of Blood

Blood is composed of two major parts: plasma and formed elements. Plasma is the liquid portion, while the formed elements include red blood cells (RBCs), white blood cells (WBCs), and platelets. Each component performs specific roles necessary for the body’s functioning. Human blood is composed of:

1. Plasma – Fluid part
2. Formed Elements – Blood cells:
   • Red Blood Cells (RBCs)
   • White Blood Cells (WBCs)
   • Platelets

Let’s understand each in detail.

1. Plasma

Plasma is the pale yellow fluid that makes up around 55% of the total blood volume. It is mainly composed of water, proteins like albumin, globulin, and fibrinogen, and dissolved substances. Plasma transports nutrients, hormones, waste products, and helps in maintaining blood pressure and volume.

Proteins present in Plasma-

• Albumin: Maintains osmotic pressure
• Fibrinogen: Helps in blood clotting
• Globulin: Functions in immunity

2. Red Blood Cells (RBCs)

Red blood cells, also known as Erythrocytes, are responsible for carrying oxygen from the lungs to the rest of the body and returning carbon dioxide to the lungs. They contain hemoglobin, an iron-rich protein that gives blood its red color. RBCs lack a nucleus and have a lifespan of about 120 days.

• Hemoglobin: Iron-containing pigment that binds with oxygen.
• Important: Anemia is caused by low hemoglobin levels.

3. White Blood Cells (WBCs)

White blood cells, also called Leukocytes, play a crucial role in the body’s immune system by protecting it from infections and foreign invaders. Unlike RBCs, they have a nucleus and are fewer in number. WBCs are divided into granulocytes and agranulocytes, each with specific immune functions.

There are 5 types of WBCs, divided into two categories:

Granulocytes:

• Neutrophils – Destroy bacteria
• Eosinophils – Fight parasites, involved in allergy
• Basophils – Release histamine during inflammation

Agranulocytes:

• Lymphocytes – Produce antibodies
• Monocytes – Engulf pathogens

Leukemia: Blood cancer caused by abnormal WBC growth.

4. Platelets (Thrombocytes)

Platelets are small, disc-shaped cell fragments that help in blood clotting. They play a key role in preventing excessive blood loss during injuries. Platelets are formed in the bone marrow and have a short lifespan, typically around 7 to 10 days.

Blood Clotting

Blood clotting is the process through which bleeding is stopped after injury. It involves a series of steps where platelets, calcium ions, and clotting proteins like fibrinogen form a mesh to seal the wound. Vitamin K is essential for proper clotting function.

Hemophilia: A genetic disorder in which blood does not clot properly.

Blood Groups

Discovered by Karl Landsteiner, Blood is classified into groups based on the presence of specific antigens. The ABO system and Rh factor are the two main systems used in blood grouping. Knowing blood compatibility is crucial during blood transfusions to prevent life-threatening reactions.

ABO Blood Group System

Rh Factor

It is important for blood transfusion and pregnancy.

• If Rh antigen is present: Rh positive (+)
• If Rh antigen is absent: Rh negative (-)

Blood Donation

Blood donation is a safe and life-saving process where a healthy person donates about 350 – 450 ml of blood. The donated blood is used for patients in need. People with O negative blood are universal donors, while those with AB positive blood are universal recipients.

• Standard blood donation: 350 – 450 ml
• Safe for healthy individuals
• O negative is universal donor
• AB positive is universal recipient

Diseases Related to Human Blood

Several diseases affect the composition and function of blood. These conditions can be inherited or acquired and often affect red cells, white cells, or platelets, leading to various health complications.

Human Blood: Important Points for RRB NTPC 2025 Exam

The following table highlights key facts that are frequently asked in the RRB NTPC exams. Memorizing these will help you quickly answer biology-based questions.

Conclusion

Understanding the structure and function of human blood is crucial for cracking the RRB NTPC 2025 exam. This topic forms the foundation for many biology-based questions. Go through these notes multiple times, revise regularly, and attempt mock questions to strengthen your preparation.