**Question:** Mucopolysaccharide hyaluronic acid is present in -

A. Skin
B. Cartilage
C. Synovial fluid
D. Blood plasma

**Core Concept:**
Hyaluronic acid (HA) is a glycosaminoglycan, a type of mucopolysaccharide, which is a complex carbohydrate. It plays a significant role in the structure and function of various tissues and organs.

**Why the Correct Answer is Right:**
Hyaluronic acid is a constituent of the extracellular matrix (ECM) of connective tissues, such as skin, cartilage, and synovial fluid. It contributes to tissue hydration, elasticity, and shock absorption. Its high molecular weight and ability to bind water make it essential for maintaining tissue integrity and structure.

**Why Each Wrong Option is Incorrect:**
In option A, HA is not primarily found in the skin. While it is present, its main role is in the dermis, which contributes to skin hydration and elasticity but is not the primary component of skin tissue.

In option B, HA is present in cartilage but not exclusively. It is one of the components of the ECM, which includes collagen and proteoglycans, and contributes to cartilage structure and function.

In option D, blood plasma contains other glycoproteins and proteins, but not HA. HA is primarily found in the ECM of various tissues, not in the blood plasma.

**Clinical Pearl:**
Understanding the distribution and role of hyaluronic acid in different tissues helps medical professionals appreciate its diverse functions in maintaining tissue health and integrity. A deeper comprehension of HA distribution can contribute to a better understanding of various medical conditions, such as skin disorders, joint diseases, and tissue repair processes.

**Correct Answer:** C. Synovial fluid

Hyaluronic acid is primarily found in synovial fluid, which lubricates and cushions the joints, allowing for smooth movement and reducing friction between bones. It is crucial for joint health and function, contributing to joint protection, nutrition, and the maintenance of joint fluid viscosity.