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A hair follicle is part of the skin that grows hair
by packing old cells together. Attached to the follicle is a sebaceous
gland, a tiny sebum-producing gland found everywhere except on the
palms, lips and soles of the feet. The thicker density of hair,
the more sebaceous glands are found.
Capillaries
are the smallest of a body's blood vessels, measuring
5-10 micrometre in diameter, which connect arterioles and venules,
and enable the interchange ofwater,oxygen,carbon dioxide, and many other nutrient and waste chemical substances between blood and surrounding tissues
Stratum Corneum ("horny layer")
The outermost layer of the epidermis (the outermost layer of the skin).
It is composed mainly of dead cells that lack nuclei. As these
dead cells slough off, they are continuously replaced by new cells from
the stratum germinativum (basale). Cells of the stratum corneum
contain keratin, a protein that helps keep the skin hydrated by
preventing water evaporation.
In addition, these cells can also absorb water, further aiding in
hydration and explaining why humans and other animals experience
wrinkling of the skin on the fingers and toes (colloquially
called "pruning") when immersed in water for prolonged periods.
Nerve Ending
Nerves Endings relay messages between the skin and brain. Nerves
in the dermis come in two forms: touch receptors that detect light
touch and pressure receptors that detect pressure and vibrations.
Arrector Pili
A microscopic band of muscle tissue
which connects a hair follicle to the dermis. When stimulated, the arrector pili will
contract and cause the hair to become more perpendicular to the skin surface (stand on
end)
Sebaceous Gland
A branched
type of acinar gland, these glands exist in humans throughout the skin
except in the palms of the hands and soles of the feet.
Sebaceous glands can usually be found in hair-covered areas, where they are connected to hair follicles.
The glands deposit sebum on the hairs, and bring it to the skin surface
along the hair shaft. The structure consisting of hair, hair follicle,
arrector pili muscle, and sebaceous gland is known as a pilosebaceous unit.
Sweat Glands
Every square inch of the skin contains 650 sweat glands. These tiny
ducts emit droplets of pespiration that cool the body as they
evaporate. Sweat glands are also used by the body to remove certain
waste and toxins from the blood.
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