Hematology

What is Blood Functions Composition & Importance in body

Blood is the life-sustaining fluid that flows through our bodies. It delivers essential nutrients and oxygen to cells. It removes waste products. It also defends us against infections. Without it, life wouldn’t be possible.

In this article, we’ll explore the definition of blood, its composition and vital functions.

What is Blood?

Blood is a specialized bodily fluid that circulates through the heart, arteries, veins, and capillaries. It plays a crucial role in maintaining homeostasis (balance in the body). It also transports nutrients, hormones, and oxygen.

An average adult has about 5 to 6 liters of blood, which accounts for about 7–8% of total body weight.

What is the Composition of Blood?

Blood is composed of both liquid and cellular components. Here is the details of liquid and cellular components.

1. Plasma (55%)

Plasma is the liquid part of blood, making up about 55% of blood volume. It is a pale yellow fluid composed of:

90–92% water
7% proteins (albumin, globulin, fibrinogen)
1–2% nutrients, electrolytes, hormones, and waste products

NOTE: Plasma serves as the medium for transporting substances throughout the body.

2. Red Blood Cells (RBCs)

Also known as erythrocytes, red blood cells carry oxygen from the lungs to body tissues. They return carbon dioxide to the lungs for exhalation.

Characteristic of erythrocytes

Lifespan: ~120 days
RBC includes hemoglobin, (a protein that binds to oxygen).
Gives blood its red color

3. White Blood Cells (WBCs)

Also called leukocytes. WBCs are the body’s defense system. They fight infections, destroy harmful pathogens, and play a key role in immunity.

Types of White blood cells

Neutrophils
Lymphocytes
Monocytes
Eosinophils
Basophils

4. Platelets (Thrombocytes)

Platelets are tiny, disc-shaped cells that help in blood clotting. When an injury occurs, they clump together to form a clot and stop bleeding.

What is the Functions of Blood

Blood performs several essential functions to keep the body healthy and functioning properly:

1. Transportation

Oxygen from lungs to tissues
Carbon dioxide from tissues to lungs
Nutrients from the digestive system
Hormones to target organs
Waste products to kidneys and liver for elimination

2. Regulation

Maintains body temperature
Regulates pH balance (acid-base)
Controls fluid balance and electrolyte levels

3. Protection

White blood cells fight infections
Platelets prevent blood loss via clotting
Antibodies neutralize harmful substances

Interesting Facts About Blood

There are eight main blood types (A, B, AB, and O – each with + or – Rh factor).
The universal donor is O-negative; the universal recipient is AB-positive.
One donation of blood can save up to three lives.
Your body makes about 2 million red blood cells every second.

Conclusion

Blood is far more than just a red fluid. It’s a complex, intelligent system that plays a vital role in survival. From transporting oxygen and nutrients to defending against disease, the functions of blood are as diverse as they are essential.