Pigment granules that impact hair color are found in the:
A) Medulla
Cortex
Cuticle
Both A and B
The correct answer and explanation is:
The correct answer is Cortex.
Hair color is determined by the presence of pigment granules, primarily located in the cortex of the hair. The cortex is the thick, fibrous middle layer of the hair shaft and contains the cells that produce pigments called melanin. There are two types of melanin: eumelanin (which is brown or black) and pheomelanin (which is yellow or red). The ratio of these two types of melanin in the cortex is what gives hair its particular color, whether blonde, brown, black, or red.
The medulla, located in the center of the hair, is often hollow or filled with air, and does not contain pigment granules. This layer is not involved in determining hair color but contributes to the overall structure of the hair. The cuticle is the outermost layer of the hair, consisting of flattened, overlapping scales that protect the inner layers from damage. It also does not contribute to hair color.
The amount and type of melanin in the cortex are influenced by genetic factors, which determine hair color. Environmental factors like UV exposure can also play a role in altering the intensity or shade of hair color by affecting the melanin in the cortex. For instance, sun exposure can lighten hair because UV rays break down melanin, leading to a reduction in pigmentation.
In summary, while the cuticle and medulla play essential roles in the structure and protection of the hair, it is the cortex that contains the pigment granules responsible for the color of hair.