part 2- Flashcards
hair, nails, sweat glands
accessory structures of the skin:
hair, nails, sweat glands, and sebaceous glands. These structures embryologically originate from the epidermis and can extend down through the dermis into the hypodermis.
what is hair made of and how does it originate?
hair is made of dead, keratinized cells and grows from the hair follicle, which is an epidermal penetration of the dermis
what is the hair shaft and where is it located?
the hair shaft is part of the hair that is not anchored to the folic, mostly exposed at the skins surface
what is the hair root, location?
- hair root is part of hair anchored in the follicle, lying below the skin surface, and ends at the hair bulb in dermis
what is the hair bulb and what does it contain?
hair bulb is the deep end of the hair follicle, located in the dermis. it surrounds the hair papilla , which contains blood capillaries and nerve endings
what is the hair matrix?
layer of actively growing basal cells in the hair root that divide and push cells outward to form the hair shaft.
why is hair unable to feel sensation?
hair is made of dead, keratinized cells, does not have sensation
why can you cut and shave hair without damaging its structure?
cut is superficial and doesn’t affect hair root or follicle
how do chemical hair removers work compared to electrolysis and plucking?
chemical hair removers act superficially while others aim to destroy the hair bulb to prevent hair growth
some functions of hair in human body?
- protection, sensory input, communication
- protects skull from the sun, traps dust and microbes, helps prevent sweat from entering the eyes
how does hair protect the body from particles and allergens?
hair in nose, ears and around eyes trap dust particles, allergens and microbes helping defend the body
how does hair have a sensory function?
hair has sensory input because it is innervated by a hair root plexus, which makes it sensitive to air movement and other disturbances , helping detect insects of other potential threats
how is hair different from the skin surface in terms of sensitivity
much more sensitive to air movement and other environmental disturbances than the skin surface
what is the arrestor pili and what is its function
arrestor pili is smooth muscle connected to each har root. contracts in response to nerve signals, causing hair shaft to ‘stand up’
why does hair shaft stand up when the arrector pili contracts?
primary purpose is to trap a layer of air for insulation
why is the erection of hair shafts (goose bumps) less effective for insulation in humans
in humans hairs are too far apart to be effective at trapping air for insulation
what is the nail bed and where is it located?
the nail bed is a specialized structure of the epidermis found at the tips of fingers and toes
what is the function of the nail body?
protects the tips of fingers and toes from mechanical stress and supports picking up small objects
composition of nail body?
made up of densely packed dead keratinocytes
where does the nail body form, and how does it grow
nail body forms at nail root where a matrix of proliferating cells from the stratum basale allows continuous growth
what is the function of sudoriferous (sweat) glands?
produce sweat to cool the body when it becomes warm
how do sweat glands develop and what type of glands are they
develop from epidermal projections into the dermis and are classified as merocrine glands which secrete by exocytosis without affecting the gland cells
main two types of sweat glands?
eccrine and apocrine glands, each secreting slightly different products
composition of eccrine sweat? primary function?
eccrine sweat is mostly water, with salt, antibodies, metabolic waste, dermcidin. major role in thermoregulation and maintaining homeostasis
Where are apocrine sweat glands found, and what makes their sweat different from eccrine sweat?
Apocrine sweat glands are found in dense hair areas like the armpits and anogenital regions. Their sweat is thicker, contains organic compounds, and is subject to bacterial decomposition, causing odor.
How are apocrine sweat glands controlled, and what role do they play in pheromones?
Apocrine sweat glands are controlled by nervous and hormonal signals and are believed to play a role in human pheromone responses
What is the mechanism behind antiperspirants?
Antiperspirants use aluminum-based compounds that precipitate in sweat ducts, forming a block that prevents sweat from reaching the skin surface.
What are two examples of modified apocrine glands and their functions?
The mammary gland produces milk for offspring, and the ceruminous gland in the ear secretes earwax to protect the ear from foreign bodies.
function of sebaceous glands?
lubricate and waterproof the skin and hair by secreting sebum which also has antibacterial properties and prevent water loss
how does secretion of sebum change during puberty
relatively in active in childhood but their secretion of sebum increases with hormonal activation during puberty
