Which statement best describes plasma in the context of fluid therapy?

• A. It is a crystalloid
• B. It is an endogenous colloid
• C. It is an exogenous colloid
• D. It has no osmotic effect

Answer: (B)

The key idea is understanding what kind of fluid plasma is and where it comes from. Plasma is the protein-rich liquid part of blood, and those proteins (especially albumin) give plasma a colloidal nature. Colloids consist of larger molecules that stay in the vascular space and generate oncotic (colloid osmotic) pressure, helping to pull water back into the blood vessels and maintain intravascular volume. Because plasma is produced by the body, it is considered endogenous. In contrast, crystalloids are small solutes that rapidly equilibrate with interstitial fluid, and exogenous colloids are substances given as therapy (like purified albumin or synthetic starches). Plasma does have an osmotic effect due to its proteins, so the option stating it has no osmotic effect is incorrect.