Hair

Definition

Hair is a filamentous biomaterial made primarily of keratin that grows from follicles found in the dermis layer of the skin. It serves various functions, including protection, regulation of body temperature, and sensory perception, playing a crucial role in the interaction between major organ systems.

5 Must Know Facts For Your Next Test

1. Hair serves as insulation by trapping air, which helps regulate body temperature in varying climates.
2. Each hair grows from a follicle in cycles that include growth (anagen), rest (telogen), and shedding (catagen).
3. The color and texture of hair are determined by genetics, specifically the types and amounts of melanin produced by melanocytes.
4. Hair can provide sensory information due to the presence of nerve endings around the follicles that respond to touch.
5. In humans, body hair has reduced in density and length compared to our primate ancestors, reflecting changes in evolutionary adaptations.

Review Questions

• How does hair contribute to the sensory capabilities of the human body?
  • Hair enhances the sensory capabilities of the human body by acting as a receptor for touch. The nerve endings surrounding hair follicles can detect even slight movements, which helps to alert the body to environmental changes or potential threats. This function plays an important role in the interaction between the integumentary system and the nervous system.
• Discuss the relationship between hair follicles and sebaceous glands in maintaining skin health.
  • Hair follicles are closely associated with sebaceous glands that secrete sebum, which is essential for maintaining healthy skin and hair. Sebum provides lubrication, preventing dryness and protecting against bacteria. This relationship highlights how the integumentary system supports overall health by ensuring both skin and hair remain moisturized and resilient.
• Evaluate how evolutionary changes in hair characteristics reflect adaptations to environmental challenges faced by early humans.
  • Evolutionary changes in human hair characteristics demonstrate adaptations to various environmental challenges faced by early humans. For example, reduced body hair may have allowed for better temperature regulation during hot climates while increased scalp hair could offer protection against UV radiation. These adaptations illustrate how physiological features like hair have evolved in response to survival needs, impacting interactions between humans and their environments over time.

Related terms

Keratin: A fibrous structural protein that is a key component of hair, skin, and nails, providing strength and resilience.

Follicle: The specialized structure in the skin from which hair grows, consisting of a bulb and surrounding cells that support hair growth.

Sebaceous Glands: Glands associated with hair follicles that secrete sebum, an oily substance that helps to lubricate and protect hair and skin.