Final answer:
Skin color is primarily determined by the pigments melanin, carotene, and hemoglobin. While diseases can affect skin color, they do so through changes in bodily functions rather than direct changes to skin pigmentation. Melanin is the main factor that causes variation in skin color across different people.
Step-by-step explanation:
The color of skin is determined by several factors, not just by physiological factors mentioned in the question. The main pigments that contribute to skin color are melanin, carotene, and hemoglobin. Melanin is the most significant determinant of skin color and is produced by melanocytes in the stratum basale of the epidermis. This melanin is then transferred into keratinocytes, which are the majority of cells found in the epidermis. Furthermore, carotene adds a yellowish tint to the skin, while hemoglobin provides a pinkish hue, which is especially noticeable in lighter skin with lower melanin levels.
Disease states can also influence skin color. For example, liver disease can lead to jaundice, characterized by a yellowing of the skin due to elevated levels of bilirubin. Addison's disease may cause a bronze coloration of the skin because of ACTH release, and oxygen deprivation can lead to cyanosis, giving the skin a bluish tint. However, these alterations in skin color relate to changes in bodily functions rather than a direct change in the skin's pigmentation.