Terminal hair

Definition

Terminal hair refers to the thick, long, and pigmented hair that typically grows on various parts of the human body, including the scalp, eyebrows, and during puberty in areas like the armpits and groin. It is distinct from vellus hair, which is finer and less pigmented. Terminal hair is characterized by its greater length and density, playing important roles in protection, thermoregulation, and sensory perception.

5 Must Know Facts For Your Next Test

1. Terminal hair is typically thicker than vellus hair and contains a medulla, which gives it strength and structure.
2. Hormonal changes during puberty trigger the transformation of vellus hair into terminal hair in certain areas of the body due to increased androgen levels.
3. Terminal hair can be affected by genetic factors, meaning some people may have more or less terminal hair than others based on their family traits.
4. In adults, terminal hair is primarily found on the scalp, face (especially in males), chest, back, abdomen, and around the genital area.
5. Conditions like alopecia can lead to loss or thinning of terminal hair, affecting its distribution and appearance on the body.

Review Questions

• What are the primary differences between terminal hair and vellus hair in terms of structure and function?
  • Terminal hair is thicker, longer, and pigmented compared to vellus hair, which is fine, short, and often lacks pigmentation. Functionally, terminal hair serves several purposes: it provides insulation and protection for the scalp and body while also playing a role in sensory perception. Vellus hair mainly serves to cover the skin surface and may help with thermal regulation but does not offer the same level of protection as terminal hair.
• How do hormonal changes during puberty affect the growth patterns of terminal hair in humans?
  • During puberty, there is an increase in androgen levels such as testosterone. These hormones stimulate the transformation of finer vellus hair into thicker terminal hair in specific regions like the armpits and groin. This change is part of normal sexual maturation, resulting in increased visibility of terminal hair in both males and females as they develop secondary sexual characteristics.
• Evaluate the implications of genetic factors on individual variations in terminal hair growth and its distribution on the human body.
  • Genetic factors play a significant role in determining individual variations in terminal hair growth patterns and distribution. Variations can include differences in thickness, density, and locations where terminal hair appears. For instance, individuals from certain ethnic backgrounds may naturally have more prominent facial or body hair due to inherited traits. Understanding these genetic influences helps explain why some people may experience conditions like hirsutism or alopecia differently from others.

Related terms

Vellus hair: Fine, short, and lightly pigmented hair that covers most of the body and is often referred to as 'peach fuzz.'

Hair follicle: A small tubular cavity in the skin from which a hair grows, playing a crucial role in the development and cycling of hair.

Androgens: Hormones, such as testosterone, that influence the growth of terminal hair during puberty and play a role in conditions like hirsutism.