Science Olympiad Integumentary System Practice Test 2025 - Free Science Olympiad Practice Questions and Study Guide

Nails are primarily composed of tightly packed keratinized epidermal cells. Keratin is a tough, fibrous protein that provides strength and resilience to the nails, much like it does for hair and the outer layer of skin. This keratinization process involves the hardening of the epidermal cells as they move from the nail matrix (located at the base of the nail) to the visible part of the nail.

This structure not only protects the fingertip but also aids in grasping and manipulating objects. The dense arrangement of these keratinized cells makes nails strong and durable, allowing them to withstand everyday wear and tear. This key characteristic is what distinguishes nails from other structures in the integumentary system, which might contain different types of tissues or proteins. For instance, hair follicles are not directly involved in nail structure, and the presence of collagen and elastin is more typical of skin layers, rather than nails specifically. Thus, the correct answer highlights the unique composition of nails and their functional significance.