Textbook Question
The portion of the hair follicle where cell divisions occur is the
(a) Shaft
(b) Matrix
(c) Root hair plexus
(d) Cuticle
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5. Integumentary System
Hair
2:12 minutesProblem 19
Textbook Question
Describe the process of hair formation, and list several factors that may influence
a. Growth cycles and b. Hair texture
Verified step by step guidance1
Step 1: Begin by understanding the anatomy of hair formation. Hair is formed in the hair follicle, which is a tube-like structure embedded in the dermis of the skin. The base of the follicle contains the hair bulb, where actively dividing cells produce the hair shaft. These cells undergo keratinization, a process where they fill with keratin protein and die, forming the hardened structure of the hair.
Step 2: Explain the growth cycles of hair. Hair growth occurs in three distinct phases: (1) Anagen (active growth phase), where cells in the hair bulb divide rapidly; (2) Catagen (transitional phase), where growth slows and the follicle shrinks; and (3) Telogen (resting phase), where the hair follicle is dormant and the hair may eventually fall out. These cycles vary in duration depending on the location of the hair and individual factors.
Step 3: Discuss factors influencing growth cycles. Several factors can affect the duration and activity of hair growth cycles, including genetics (which determines the length of the anagen phase), hormonal changes (e.g., during pregnancy or menopause), age (growth cycles tend to shorten with age), and health conditions (e.g., alopecia or thyroid disorders). Environmental factors like stress and nutrition also play a role.
Step 4: Describe the factors influencing hair texture. Hair texture is determined by the shape of the hair follicle and the distribution of keratin within the hair shaft. Round follicles produce straight hair, while oval or flat follicles result in wavy or curly hair. Genetic factors are the primary determinant of follicle shape, but environmental factors like humidity and chemical treatments can temporarily alter texture.
Step 5: Summarize the importance of understanding these factors. Recognizing the biological and external influences on hair growth and texture can help in diagnosing hair-related conditions and tailoring treatments or care routines to maintain healthy hair.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hair Formation Process
Hair formation begins in the hair follicle, where cells proliferate and differentiate to form the hair shaft. This process involves the growth phase (anagen), transitional phase (catagen), and resting phase (telogen). During anagen, the hair grows actively, while catagen marks the end of growth, and telogen is a resting period before the hair falls out and a new cycle begins.
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Growth Cycles
Hair growth cycles are influenced by various factors, including genetics, hormonal changes, and environmental conditions. Each hair follicle operates independently, meaning that while some hairs are in the growth phase, others may be in resting or shedding phases. Understanding these cycles is crucial for comprehending how hair density and length can vary over time.
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Hair Texture Influencers
Hair texture is primarily determined by the shape of the hair follicle and the distribution of keratin proteins within the hair shaft. Factors such as genetics, ethnicity, and health can significantly influence texture, leading to variations like straight, wavy, or curly hair. Additionally, external factors like humidity and hair care practices can also affect the appearance and feel of hair texture.
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