Chapter 6 - Section 6.2 - Study Guide - Assess Your Learning Outcomes - Page 199: 9

Hair serves several functions in the human body, and there are various types of hair with distinct functions and distributions across the body. Here are the primary types of hair and their functions: **1. Terminal Hair:** - **Function:** Terminal hair is the thicker, coarser hair found on the scalp, eyebrows, eyelashes, armpits, pubic area, and in varying degrees on the chest, back, and limbs. Its main functions include: - Providing protection: Scalp hair, for example, protects the scalp from UV radiation and impacts. - Sensory functions: Eyelashes and eyebrows help protect the eyes by detecting and blocking foreign particles. - Sexual dimorphism: Terminal hair patterns can differ between males and females and play a role in sexual attraction and mate selection. **2. Vellus Hair:** - **Function:** Vellus hair is fine, short, and barely noticeable hair found on most areas of the body, including the face, arms, and legs. Its functions include: - Providing a light protective barrier for the skin. - Contributing to thermal regulation by trapping a small layer of air near the skin's surface. - Maintaining sensitivity to touch in areas such as the face. **3. Lanugo Hair (Fetal Hair):** - **Function:** Lanugo hair is very fine, soft, and downy hair that covers the entire body of a developing fetus, including the face, back, and limbs. Its functions include: - Providing an insulating layer to keep the developing fetus warm in the womb. - Protecting the delicate fetal skin from the amniotic fluid. **4. Androgenic (Sexual) Hair:** - **Function:** Androgenic hair is associated with secondary sexual characteristics and is influenced by sex hormones (androgens) like testosterone. Its functions include: - Developing in response to puberty and the influence of sex hormones. - Serving as a secondary sexual characteristic, such as facial hair in men and underarm hair in both sexes. **5. Armpit and Pubic Hair:** - **Function:** Armpit and pubic hair are subsets of terminal hair with specific distributions. Their functions include: - Aiding in the diffusion of pheromones, which are chemical signals related to reproduction and attraction. - Reducing friction in areas where skin rubs against skin. **6. Nose and Ear Hair:** - **Function:** Nose and ear hair are types of terminal hair with specific functions: - They help filter out dust, debris, and foreign particles from entering the nasal passages and ear canals, protecting the respiratory and auditory systems. The distribution and functions of different types of hair vary among individuals and populations and can be influenced by genetic and hormonal factors. Each type of hair serves a specific purpose in maintaining the health and functionality of various parts of the body.

Hair serves several functions in the human body, and there are various types of hair with distinct functions and distributions across the body. Here are the primary types of hair and their functions: **1. Terminal Hair:** - **Function:** Terminal hair is the thicker, coarser hair found on the scalp, eyebrows, eyelashes, armpits, pubic area, and in varying degrees on the chest, back, and limbs. Its main functions include: - Providing protection: Scalp hair, for example, protects the scalp from UV radiation and impacts. - Sensory functions: Eyelashes and eyebrows help protect the eyes by detecting and blocking foreign particles. - Sexual dimorphism: Terminal hair patterns can differ between males and females and play a role in sexual attraction and mate selection. **2. Vellus Hair:** - **Function:** Vellus hair is fine, short, and barely noticeable hair found on most areas of the body, including the face, arms, and legs. Its functions include: - Providing a light protective barrier for the skin. - Contributing to thermal regulation by trapping a small layer of air near the skin's surface. - Maintaining sensitivity to touch in areas such as the face. **3. Lanugo Hair (Fetal Hair):** - **Function:** Lanugo hair is very fine, soft, and downy hair that covers the entire body of a developing fetus, including the face, back, and limbs. Its functions include: - Providing an insulating layer to keep the developing fetus warm in the womb. - Protecting the delicate fetal skin from the amniotic fluid. **4. Androgenic (Sexual) Hair:** - **Function:** Androgenic hair is associated with secondary sexual characteristics and is influenced by sex hormones (androgens) like testosterone. Its functions include: - Developing in response to puberty and the influence of sex hormones. - Serving as a secondary sexual characteristic, such as facial hair in men and underarm hair in both sexes. **5. Armpit and Pubic Hair:** - **Function:** Armpit and pubic hair are subsets of terminal hair with specific distributions. Their functions include: - Aiding in the diffusion of pheromones, which are chemical signals related to reproduction and attraction. - Reducing friction in areas where skin rubs against skin. **6. Nose and Ear Hair:** - **Function:** Nose and ear hair are types of terminal hair with specific functions: - They help filter out dust, debris, and foreign particles from entering the nasal passages and ear canals, protecting the respiratory and auditory systems. The distribution and functions of different types of hair vary among individuals and populations and can be influenced by genetic and hormonal factors. Each type of hair serves a specific purpose in maintaining the health and functionality of various parts of the body.