Understanding Hair Structure Statements

This question asks us to identify the correct statements about the structure and components of human hair, specifically focusing on the medulla, cortex, and cuticle layers.

Statement Analysis

Statement A: The protein of medulla is distinct from the proteins of cortex and cuticle.

• Hair is primarily made of a protein called keratin.
• The hair shaft consists of three main layers: the cuticle (outermost), the cortex (middle), and the medulla (innermost core).
• While all layers are largely composed of keratin, the specific types and arrangements of keratin proteins can differ between these layers.
• Research suggests that the medulla may have a less organized keratin structure or different keratin types compared to the more tightly packed cortex and cuticle.
• Therefore, it is considered that the protein composition of the medulla can be distinct from that of the cortex and cuticle.
• Conclusion: Statement A is correct.

Statement B: Medulla is not present in all human hairs.

• The medulla is the central, hollow core of a hair strand.
• Not all hair types or even all individual hairs on the human body possess a medulla.
• Fine hairs, such as vellus hairs (the short, fine, light-colored hair found on much of the body), often lack a medulla entirely.
• Thicker hairs, like terminal hairs (found on the scalp, eyebrows, and pubic areas), typically have a medulla.
• The presence and pattern of the medulla can vary depending on the body location, hair type, and even individual factors.
• Conclusion: Statement B is correct.

Statement C: The diameter of medulla is largest in the hair of the child, and smallest in old age.

• Hair diameter can change throughout a person's life. Generally, hair tends to become finer with age, and its diameter may decrease.
• However, specific claims about the medulla's diameter being largest in children and smallest in old age are not universally established facts and can be complex.
• While overall hair thickness might decrease with age, attributing specific changes solely to the medulla's diameter across these age groups requires specific evidence not commonly cited in general hair anatomy.
• Hair thickness varies greatly among individuals and hair types, making such broad generalizations about the medulla's diameter challenging.
• Conclusion: Statement C is likely incorrect or at least not a universally accepted fact.

Statement D: Medulla appears as a network of cellular connections without any spaces or gaps.

• The structure of the medulla is characterized by cells and air spaces.
• The medullary cells are typically arranged loosely, creating spaces or gaps within the core of the hair shaft.
• It does not form a solid, continuous network without interruptions.
• The presence of air spaces is a notable feature of the medulla's structure.
• Conclusion: Statement D is incorrect.

Summary of Correct Statements

Based on the analysis, statements A and B are considered correct descriptions related to hair structure.

• Statement A is correct because the protein composition of the medulla can differ from the cortex and cuticle.
• Statement B is correct because not all human hairs contain a medulla.