Vellus hair is the fine, soft, and usually unpigmented hair that covers much of the human body. Unlike terminal hair, which is thicker and darker, vellus hair serves several purposes, including providing thermal insulation and contributing to the sensory functions of the skin. It is most commonly found on areas like the face, arms, and legs, playing a role in regulating body temperature and enhancing the sense of touch.
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Vellus hair is often referred to as 'peach fuzz' due to its soft texture and light color.
In adults, vellus hair covers most of the body, while terminal hair is limited to specific regions.
Hormonal changes during puberty can cause some vellus hair to become terminal hair, particularly in areas such as the underarms and pubic region.
Vellus hair plays a role in thermoregulation by trapping a layer of air close to the skin surface, helping to maintain body temperature.
While vellus hair is mostly unpigmented, it can appear darker or more noticeable depending on individual skin tone and lighting.
Review Questions
How does vellus hair differ from terminal hair in terms of structure and function?
Vellus hair differs from terminal hair primarily in its structure and function. Vellus hair is fine, soft, and often unpigmented, while terminal hair is thicker, darker, and longer. Functionally, vellus hair helps with thermal insulation and sensitivity in various parts of the body, while terminal hair serves more prominent roles in areas like the scalp and face where aesthetics and protection are more important.
Discuss the role of hormonal changes in transforming vellus hair into terminal hair during puberty.
During puberty, increased levels of hormones such as testosterone can stimulate the growth of terminal hair from previously existing vellus hair follicles. This transformation typically occurs in specific areas such as the underarms, face, and pubic region. The hormonal influence not only increases the thickness and pigmentation of the hair but also triggers changes in associated structures like sebaceous glands, enhancing their functionality.
Evaluate the implications of vellus hair's sensory functions on overall human physiology.
Vellus hair contributes significantly to human physiology by enhancing sensory perception through its interaction with nerve endings in the skin. This sensory feedback is crucial for detecting subtle changes in temperature and texture, which can alert individuals to environmental changes or potential threats. Moreover, the presence of vellus hair aids in thermoregulation by trapping air close to the skin surface. Evaluating these functions highlights how seemingly minor features like vellus hair play a vital role in overall bodily awareness and adaptive responses.
Related terms
Terminal hair: Terminal hair refers to the thicker, darker, and longer hair that typically grows on the scalp, face, and pubic regions during and after puberty.
Hair follicle: A hair follicle is a small, tube-like structure in the skin that anchors each hair strand and is responsible for its growth.
Sebaceous glands: Sebaceous glands are small oil-producing glands located in the skin that help keep hair moisturized and contribute to skin health.