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Questions and Answers
Which structure serves as the origin point for hair growth?
Which structure serves as the origin point for hair growth?
What is the primary composition of hair?
What is the primary composition of hair?
Which part of the hair contains mitotically active cells?
Which part of the hair contains mitotically active cells?
What role does the hair papilla play in hair structure?
What role does the hair papilla play in hair structure?
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Which layer of the hair is responsible for giving it strength and flexibility?
Which layer of the hair is responsible for giving it strength and flexibility?
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Where in the skin do hair follicles originate?
Where in the skin do hair follicles originate?
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Which layer of the hair is not always present in every hair strand?
Which layer of the hair is not always present in every hair strand?
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What is the role of the sebaceous glands associated with hair follicles?
What is the role of the sebaceous glands associated with hair follicles?
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What primarily determines hair texture?
What primarily determines hair texture?
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What is the role of keratinocytes in hair growth?
What is the role of keratinocytes in hair growth?
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Which part of the hair is considered to be completely dead?
Which part of the hair is considered to be completely dead?
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What substance is the hair primarily composed of?
What substance is the hair primarily composed of?
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Which procedure aims to destroy the hair bulb to prevent hair growth?
Which procedure aims to destroy the hair bulb to prevent hair growth?
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What is the internal root sheath's function?
What is the internal root sheath's function?
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Which layer of the hair follicle is an extension of the epidermis?
Which layer of the hair follicle is an extension of the epidermis?
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What is NOT one of the functions of hair?
What is NOT one of the functions of hair?
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What is the primary function of hair in the nose and ears?
What is the primary function of hair in the nose and ears?
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Which phase of hair growth is characterized by rapid cell division at the root?
Which phase of hair growth is characterized by rapid cell division at the root?
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What triggers the contraction of the arrector pili muscle?
What triggers the contraction of the arrector pili muscle?
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During which phase of hair growth is the hair follicle at rest?
During which phase of hair growth is the hair follicle at rest?
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How often is it typical for a person to lose and replace hair daily?
How often is it typical for a person to lose and replace hair daily?
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What is the consequence of hormonal changes on hair?
What is the consequence of hormonal changes on hair?
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What pigment primarily determines the color of hair?
What pigment primarily determines the color of hair?
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What phenomenon occurs when the arrector pili muscle contracts?
What phenomenon occurs when the arrector pili muscle contracts?
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What causes different hair colors in individuals?
What causes different hair colors in individuals?
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What happens to melanin production as a person ages?
What happens to melanin production as a person ages?
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What is the primary function of the nail body?
What is the primary function of the nail body?
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Where does the nail body form?
Where does the nail body form?
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What gives the nail bed its pink appearance?
What gives the nail bed its pink appearance?
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What is the lunula?
What is the lunula?
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Which part of the nail overlies the sides of the nail body?
Which part of the nail overlies the sides of the nail body?
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What do sudoriferous glands produce when the body becomes warm?
What do sudoriferous glands produce when the body becomes warm?
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What classification do sweat glands fall under due to their mode of secretion?
What classification do sweat glands fall under due to their mode of secretion?
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Which type of sweat gland is primarily involved in thermoregulation?
Which type of sweat gland is primarily involved in thermoregulation?
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Where are eccrine sweat glands most abundant on the body?
Where are eccrine sweat glands most abundant on the body?
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What additional compounds are found in apocrine sweat that contribute to scent?
What additional compounds are found in apocrine sweat that contribute to scent?
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What role do aluminum-based compounds play in commercial antiperspirants?
What role do aluminum-based compounds play in commercial antiperspirants?
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What triggers the release of sweat from apocrine sweat glands?
What triggers the release of sweat from apocrine sweat glands?
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How does eccrine sweat differ in composition compared to apocrine sweat?
How does eccrine sweat differ in composition compared to apocrine sweat?
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What physiological function is primarily served by sweating?
What physiological function is primarily served by sweating?
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Study Notes
Accessory Structures of the Skin
- Hair, nails, sweat glands, and sebaceous glands are accessory structures of the skin.
- These structures develop from the epidermis and extend into the dermis and hypodermis.
Hair
- Hair is a keratinous filament growing out of the epidermis.
- Mainly made of dead, keratinized cells.
- Hair follicles are epidermal penetrations of the dermis where hair strands originate.
- The hair shaft is the part of the hair above the skin surface.
- The hair root is the part of the hair anchored in the follicle, below the skin surface.
- The hair bulb is the end of the hair root in the dermis, containing the hair matrix.
- The hair matrix is a layer of actively dividing basal cells.
- The hair bulb surrounds the hair papilla, composed of connective tissue with blood capillaries and nerve endings.
- The hair shaft is composed of three layers: medulla, cortex, and cuticle.
- The medulla is the central core, surrounded by the cortex, a layer of compressed, keratinized cells.
- The cuticle is the outermost layer of hard, keratinized cells.
- Hair texture depends on the shape and structure of the cortex and medulla.
- Hair growth begins with the production of keratinocytes by the hair bulb.
- New cells push the hair shaft up through the follicle towards the surface.
- Keratinization is completed as cells reach the skin surface.
- Hair is completely dead and composed of keratin, lacking sensation.
- Cutting or shaving hair only affects the shaft.
- Hair growth occurs in three phases: anagen, catagen, and telogen.
- The anagen phase is the active growth phase, lasting from 2 to 7 years.
- During the catagen phase, the hair follicle transitions to rest, lasting 2 to 3 weeks.
- The telogen phase is a resting phase lasting 2 to 4 months, without new growth.
- A new anagen phase follows the telogen phase, with new hair production pushing out the old.
- Hair grows at a rate of 0.3 millimeters per day during the anagen phase.
- Hair loss occurs when shedding exceeds replacement, due to hormonal changes, diet, aging, or hormone influence.
Nails
- The nail bed is a specialized structure of the epidermis at the tips of fingers and toes.
- The nail body forms atop the nail bed, protecting the tips of fingers and toes.
- The nail body is composed of densely packed dead keratinocytes.
- The nail body forms at the nail root, containing the nail matrix, a proliferating cell layer.
- The lateral nail fold overlaps the nail, anchoring the nail body.
- The cuticle is the nail fold meeting the proximal end of the nail body.
- The nail bed is highly vascular, making the nail appear pink, except for the lunula.
- The lunula is a crescent-shaped region at the nail base, where a thick epithelial layer covers the nail matrix.
- The hyponychium is the thickened layer of stratum corneum beneath the free edge of the nail.
Sweat Glands
- Sweat glands develop from epidermal projections into the dermis.
- Sweat glands are classified as merocrine glands, secreting through ducts without affecting the gland cells.
- There are two types of sweat glands: eccrine and apocrine.
- Eccrine sweat glands produce hypotonic sweat for thermoregulation.
- Eccrine glands are found on the skin surface, especially on palms, soles, and foreheads.
- Eccrine sweat glands are coiled glands in the dermis, with ducts leading to pores on the skin surface.
- Eccrine sweat is primarily water with salt, antibodies, metabolic waste, and dermcidin.
- Eccrine glands play a crucial role in thermoregulation and homeostasis.
- Apocrine sweat glands are associated with hair follicles in hairy areas like armpits and genitalia.
- Apocrine glands are larger than eccrine glands, lying deeper in the dermis or hypodermis.
- Apocrine sweat includes organic compounds, making it thicker and prone to odor upon bacterial decomposition.
- Apocrine sweat release is controlled by the nervous system and hormones, potentially playing a role in pheromones.
- Antiperspirants use aluminum-based compounds to block sweat ducts and reduce sweat production.
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Description
This quiz covers the accessory structures of the skin, including hair, nails, sweat glands, and sebaceous glands. Understand the anatomy and functions of hair, hair follicles, and the different layers of hair structure. Test your knowledge on how these components interact with the skin's layers.
