Difference Between Serum and Plasma, Definition and Functions
Khushboo Goyal29 May, 2025
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Difference Between Serum and Plasma: Plasma and serum are derived from the liquid portion of blood, but their distinctions are significant. Continue reading to learn about the difference between serum and plasma.
Blood, a fluid connective tissue, circulates throughout the body, transporting vital nutrients, oxygen, and metabolic waste products. It also plays a vital role in regulating body temperature and pH levels by interacting with acids and bases. Blood primarily comprises red blood cells (RBCs), white blood cells (WBCs), plasma, and serum. It is a key component of various physiological processes. Plasma and serum are routinely used to identify a patient's blood group in blood group tests. Plasma and serum can be separated using blood centrifugation, which considers weight, size, and density factors. Serum is the liquid obtained after blood coagulation, while plasma is obtained by treating blood with anticoagulant substances.| NEET Biology Syllabus | NEET Biology Diagrams |
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Difference Between Serum and Plasma Overview
Although plasma and serum are frequently regarded as interchangeable, they are unique blood components. This article will clarify the difference between serum and plasma. Plasma is around 55% of total blood volume and is the liquid portion of blood. It is composed of 90% water and contains vital components such as fibrinogen, which is necessary for normal blood clotting, and albumin, which maintains fluid integrity in blood vessels, preventing leakage into surrounding tissues. The primary function of plasma is to transport proteins, nutrients, antibodies, hormones, and other substances throughout the body. Additionally, as plasma circulates, cells deposit waste into it, contributing to its role in waste removal. Serum, on the other hand, is essentially plasma that has been stripped of clotting factors and blood cells. During the process of removing clotting factors through centrifugation, fibrinogen is converted to fibrin. Fibrin is an insoluble protein that plays a key role in tissue repair by forming clots over wounds, thereby preventing excessive blood flow.Difference Between Serum and Plasma
The main difference between serum and plasma is their physical state. Plasma is liquid, while serum is a fluid. Although they share most components, plasma contains fibrinogen, which is absent in serum. Both plasma and serum can be separated from blood using a centrifuge. It is important to note that serum is obtained after blood clotting, while plasma can be obtained before blood coagulation. Serum is primarily used for blood typing and is a key component in diagnostic testing. In contrast, plasma is primarily used in processes related to blood clotting. The table below summarizes the key difference between serum and plasma:
| Difference Between Serum and Plasma | ||
|---|---|---|
| Characteristics | Plasma | Serum |
| 1. Definition | Plasma is a yellowish, slightly alkaline fluid with suspended blood cells. | Serum is the transparent yellow fluid obtained when blood clots naturally. |
| 2. Clotting factors | Plasma is the fluid containing agents responsible for blood clotting. | Serum is the liquid portion of blood without the presence of clotting factors. |
| 3. Composition | Plasma consists of all suspended blood cells and proteins, salts, lipids, and glucose. | Serum comprises proteins, electrolytes, antibodies, antigens, and hormones. |
| 4. Water content | Plasma has a water content ranging from 92-95%. | Serum is composed of 90% water. |
| 5. Components | Plasma contains both clotting factors and water. | Serum includes proteins such as albumin and globulins. |
| 6. Fibrinogen | Plasma contains fibrinogen. | Fibrinogen is absent in serum. |
| 7. Cell arrangement | Cells in plasma are not attached and remain suspended. | Cells in serum are typically attached together through clot formation. |
| 8. Method of Separation | Plasma is acquired by spinning blood before the clotting process. | Serum is obtained by spinning blood after it has clotted. |
| 9. Use of Anti-coagulant | An anticoagulant is necessary to obtain plasma. | No anticoagulant is required to separate serum. |
| 10. Feasibility of Separation | Plasma separation is comparatively easier and more cost-effective. | Separating serum demands higher expertise, expenses, and time. |
| 11. Volume in blood | Plasma makes up 55% of the total blood volume. | Serum constitutes a smaller volume compared to plasma. |
| 12. Density | Plasma has a density of 1.025g/ml. | The density of serum is 1.024g/ml. |
| 13. Storage | Frozen plasma can be stored for up to a year. | Serum can be stored at 2-6 degrees Celsius for several days. |
| 14. Discoloration | Plasma tends to discolor over time. | Serum does not undergo discoloration upon standing. |
| 15. Importance | Plasma functions in transporting excretory metabolites and materials, contributing to blood pressure maintenance and body temperature regulation. | Serum serves as the primary source of electrolytes. |
| 16. Associated terms | Plasmapheresis refers to the isolation of plasma from blood using centrifugation. | The study of serum for diagnostic purposes is known as serology. |
| 17. Uses | Plasma is administered to patients lacking blood cells and those with conditions like hemophilia, shocks, burns, and clotting problems. | Human serum is commonly used for diagnostic testing, while animal seras are used for anti-venom, antitoxins, and vaccinations. They also find therapeutic use in humans. |
Plasma Definition
Plasma is the liquid component of blood, comprising more than half its volume composition. It contains a suspension of platelets and white blood cells. The plasma composition includes water, proteins, sugars, mineral salts, hormones, fats, and vitamins. Plasma is distinguished from blood by its liquid nature. It plays an important role in regulating blood pressure within healthy limits and facilitating the transportation of essential nutrients, minerals, proteins, and hormones to specific locations in the body. Plasma accounts for 55% of the total volume of blood. Despite the overall red appearance of blood, plasma itself is a pale yellow color, primarily due to its composition, which is 90% water. V arious enzymes and salts are present in plasma, as well as antibodies that play a vital role in combating infections and diseases. Plasma also carries nutrients, hormones, and proteins, ensuring delivery to diverse cells throughout the body.
Functions of Plasma
Given that plasma is a crucial component of human blood, it fulfills several vital roles, which include:
- Coagulation: Plasma contains various substances, including proteins like thrombin and fibrinogen, that play a pivotal role in the clotting process, preventing excessive bleeding.
- Immunity: Within plasma, disease-fighting proteins contribute to building a robust immune system, safeguarding the body from harmful diseases.
- Blood Pressure: The protein albumin in plasma maintains oncotic pressure, preventing fluid leakage into the body and skin. This protein also ensures proper blood flow through the vessels.
- Transportation: Plasma is crucial in transporting nutrients, hormones, proteins, and other essential substances throughout the body. Additionally, it facilitates the removal of waste products, transporting them to organs like the lungs, liver, or skin.
- Body Temperature: Plasma balances the gain and loss of heat within the body, aiding in maintaining a stable body temperature.
- pH Balance: The diverse substances present in plasma work collectively to maintain a normal pH level, supporting the optimal functioning of cells.
Serum Definition
After blood coagulation, serum is the remaining component of plasma. Serum can also be defined as blood plasma without fibrinogens. It comprises all proteins, antibodies, electrolytes, hormones, antigens, and exogenous substances that do not participate in blood clotting. Serum serves as the non-clotting solute in blood. It is a key source of electrolytes and the preferred blood component for blood group testing. Serum is also used in various diagnostic tests to assess levels of proteins, cholesterol, sugar, and other elements in the bloodstream. The serum of individuals recovering from an illness can be valuable in treating the same disease in others. The antibodies generated during successful recovery are potent defenders against the pathogen. Both blood serum and plasma are substantial reservoirs of biomarkers. Salts, lipids, multiple degradation mechanisms, and post-translational modifications influence their extensive dynamic range.
Functions of Serum
Similar to plasma, serum plays a variety of roles, including:
- Human serum facilitates circulating exogenous and endogenous fluids within the bloodstream. It aids in transporting hormones and fatty acids, ensuring the optimal functioning of cells.
- Serum contributes to the dissemination of antibiotics throughout the body. The albumin protein within serum plays a crucial role by binding to therapeutic substances in these antibiotics, facilitating their transport across the body.
Difference Between Serum and Plasma
What is the major difference between serum and plasma?
Why is plasma used instead of serum?
What is the clinical use of serum and plasma?
What color is plasma?
What is called serum?
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