Blood Plasma: Composition, Functions, and Importance

Blood is the vital fluid that sustains life, carrying oxygen, nutrients, hormones, and waste throughout the body. While red and white blood cells often take the spotlight, a lesser-known yet crucial component is blood plasma. Accounting for over 50% of total blood volume, plasma serves as the medium that supports and transports blood cells and other substances.

In this article, we’ll explore what blood plasma is, its composition, functions, clinical significance, and its role in diagnostics and medicine—all explained in a simple and exam-friendly format.

Whether you’re preparing for competitive exams like UPSC, SSC, NEET, or just curious about how your body works, this guide will help you understand the role of this golden liquid.

What is Blood Plasma?

◾Blood plasma is the straw-colored, liquid component of blood that remains after removing all the blood cells.

◾It constitutes approximately 55% of the total blood volume and is about 90-92% water. The rest is made up of proteins, electrolytes, nutrients, hormones, and waste products.

🔹 Color: Pale yellow or straw-colored
🔹 pH: Slightly alkaline (~7.35–7.45)
🔹 Volume in an average adult: ~3 liters

📗Also Read: Composition of Blood Details Notes

Composition of Blood Plasma

Understanding the components of plasma is key to understanding its diverse functions. The major constituents include:

◾ Water (90–92%)

🔹 Acts as a solvent and medium for transport
🔹 Helps regulate body temperature

◾ Plasma Proteins (6–8%)

🔺 Albumin (60%)
🔹 Maintains oncotic pressure and transports substances

🔺 Globulins (36%)
🔹 Includes antibodies (immunoglobulins) for immune defense

🔺 Fibrinogen (4%)
🔹 Essential for blood clotting (coagulation)

◾ Inorganic Salts/Electrolytes

🔹 Sodium (Na⁺), Potassium (K⁺), Calcium (Ca²⁺), Magnesium (Mg²⁺)
🔹 Maintain osmotic balance, nerve function, and muscle contraction

◾ Nutrients

🔹 Glucose, amino acids, fatty acids, vitamins, etc.
🔹 Supplied by digestion and absorbed into plasma

◾ Hormones & Enzymes

🔹 Transported to target organs via plasma

◾ Metabolic Wastes

🔹 Urea, uric acid, creatinine, CO₂
🔹 Carried to excretory organs for elimination

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Functions of Blood Plasma

Plasma performs a wide array of functions essential to survival:

◾ 1. Transport

🔹 Carries RBCs, WBCs, and platelets
🔹 Transports oxygen, CO₂, nutrients, hormones, enzymes, and waste

◾ 2. Regulation

🔹 Helps maintain pH balance, temperature, and fluid-electrolyte balance

◾ 3. Immunity

🔹 Contains immunoglobulins (antibodies) that defend against pathogens

◾ 4. Blood Clotting

🔹 Fibrinogen and clotting factors help in forming blood clots during injury

◾ 5. Osmotic Pressure

🔹 Albumin maintains colloid osmotic pressure, preventing tissue swelling (edema)

◾ 6. Homeostasis

🔹 Acts as a buffer and helps maintain internal equilibrium

📗Don’t Miss: Why is Bone Marrow called the Factory of Blood Cells?

Types of Plasma

◾ Fresh Frozen Plasma (FFP)

🔹 Used in medical treatments, stored at -18°C or below

◾ Convalescent Plasma

🔹 Collected from recovered COVID-19 or disease patients; rich in antibodies

Plasma vs Serum: What’s the Difference?

Feature	Plasma	Serum
Clotting factors	Present	Absent
Fibrinogen	Present	Absent
Obtained by	Centrifugation with anticoagulants	Centrifugation after clotting
Use	Transfusions, lab tests	Diagnostic tests (like blood sugar, cholesterol)

Clinical Importance of Plasma

◾ 1. Plasma Donation

🔹 Just like donating blood, individuals can donate plasma
🔹 Used to make plasma-derived therapies: for hemophilia, immune deficiencies, burns, and more

◾ 2. Medical Treatments

🔹 Plasma transfusion is critical in patients with liver disease, burns, or clotting disorders

◾ 3. Diagnostic Tool

🔹 Plasma is often analyzed to check for glucose, electrolytes, hormones, enzymes, and disease markers

Plasma in Modern Medicine

Blood plasma has become a vital resource in biotechnology and pharmaceutical research. Some important applications include:

◾ Immunotherapy

🔹 Plasma-derived immunoglobulins are used for treating autoimmune diseases and infections

◾ Plasma Fractionation

🔹 The process of separating plasma components (e.g., albumin, clotting factors) for therapeutic use

◾ Vaccine Development

🔹 Plasma antibodies play a role in understanding immune responses

Interesting Facts About Blood Plasma

🔹 Plasma makes up about 5% of human body weight
🔹 The term “plasma” was first used in the blood context by Charles Darwin’s cousin, William F. Donné
🔹 Plasma is sometimes referred to as “the river of life“
🔹 The American Red Cross separates about 10 million liters of plasma annually for medical use

Relevance in Competitive Exams

In exams like UPSC, SSC, NEET, and State PSCs, questions related to blood plasma often appear under Biology or General Science. Some examples:

🔹Sample Questions

Q1: What is the function of fibrinogen present in blood plasma?
a) Oxygen transport
b) Clot formation ✅
c) Immunity
d) Temperature regulation

Q2: Which of the following plasma proteins is primarily responsible for maintaining osmotic pressure in the blood?
a) Globulin
b) Fibrinogen
c) Hemoglobin
d) Albumin ✅

Q3: What percentage of human blood is composed of plasma?
a) 30%
b) 45%
c) 55% ✅
d) 70%

Q4: Which component of blood plasma helps in the process of blood coagulation?
a) Albumin
b) Fibrinogen ✅
c) Globulin
d) Urea

Q5: Which of the following is not a component of blood plasma?
a) Red Blood Cells ✅
b) Water
c) Plasma proteins
d) Electrolytes

Q6: In a healthy human, the pH of blood plasma is approximately:
a) 6.8
b) 7.0
c) 7.4 ✅
d) 8.0

Conclusion

Though often overlooked, blood plasma is the unsung hero of the circulatory system. From transporting vital substances and regulating body functions to defending against diseases and enabling life-saving treatments, plasma is truly indispensable. As research and medicine evolve, plasma’s potential in diagnosis, therapy, and immunology continues to grow.

So next time you think of blood, don’t forget the “liquid gold” that makes it all possible — blood plasma.

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