Transcript PP – The Integumentary System

The Integumentary System
Skin, Hair, Glands, Nails
Anatomy & Physiology Ch. 5
Learning Targets
• Identify the anatomical structures of the
integumentary system.
• Explain the role of skin and all of its
accessory organs.
• Describe the diseases/disorders
of the integumentary system.
Human skin…..
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is the largest organ.
it serves as a protective covering.
it helps regulate body temp.
it prevents water loss.
it houses sensory receptors.
it excretes wastes.
Integumentary System
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Three layers
– Skin
1. Epidermis
2. Dermis
3. Hypodermis (Subcutaneous layer)
• Adipose
– Accessory Structures
• Hair - Nails -sebaceous glands
• sweat glands (4 types)
• The skin is composed of 3 layers; the
epidermis (superficial), the dermis
(middle) and the hypodermis (deep).
Epidermis
• composed of stratified squamous.
• lacks blood vessels – no vascularization.
• prevents water loss by secreting protein,
keratin.
• keratinization of cells takes about 2 weeks.
• No innervation – lacks nerves.
Keratinized stratified squamous
Epidermis (cont)
• Contains cells called melanocytes that
produce melanin (absorbs light energy
& protects deeper cells); melanin gives
skin its color.
Melanocyte
Skin Color
• All people have similar numbers of
melanocytes.
• Skin colors result from differences in the
amount of melanin that melanocytes
produce and the distribution & size of
the melanin granules.
• Albinism - inability to produce melanin.
Dermis
• Is made up of two layers.
• Top layer (papillary layer) composed of
areolar or loose connective tissue.
• Bottom layer (reticular layer) composed of
dense connective tissue.
• Well vascularized & innervated.
• Also contains accessory structures such as;
hair follicles, sebaceous glands, and sweat
glands.
Hypodermis
• Made of adipose tissue and some loose
connective tissue.
• Insulates body from losing too much heat.
• Also known as the subcutaneous layer.
• Men and women store subcutaneous fat
differently.
Hair…
• Composed of epidermal cells that have
keratinized and died .
• Hair color is determined by the type and
amount of pigment the melanocytes
produce.
• Arrector pili muscle - surrounds hair follicle
& contracts when a person is cold or
frightened. What are “goose bumps’?
Sebaceous Glands…
• a gland located around the hair follicle
which secretes its contents when contracted
by the arrector pili.
• secrete an oily mixture of fat and cellular
debris called sebum which keeps the hair
and skin soft, pliable, and waterproof.
• this is why hair gets oily when not washed.
Nails…
• Composed of dead stratified squamous
epithelial cells which are extremely
keratinized.
• Nail production occurs at the nail root which
is underneath the skin and proximal to the
visible nail.
• Nails are basically clear and appear pink over
skin because of underlying blood vessels.
Sweat Glands (Exocrine Glands)
1.
Eccrine Glands…
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respond to elevated body temp. due
to heat or exercise.
cool by allowing water to be
evaporated from skin lowering temp.
common on forehead, neck, and
back.
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Sweat Glands (Exocrine Glands)
• release fluids thru pores.
• gland located in dermis but releases
fluid through tube onto the top of the
epidermis.
• sweat = water + salts (mainly sodium
chloride) and other wastes.
Where do you have the most eccrine glands?
Sweat glands (cont.)
2. Apocrine glands….
• active when a person is emotionally
upset, frightened, or in pain.
• found under the armpits and in the
groin.
• sweat is food for bacteria, which just
increases the bad smell.
Other Integumentary Glands
- Ceruminous glands - secrete ear
wax to trap foreign particles before
reaching the ear drum.
Why does ear wax smell bad?
- Mammary glands - secrete milk.
Regulation of Body Temperature
• Regulation is important b/c heat affects
the rate of metabolic reactions.
• When temp rises above the set point,
dermal blood vessels dilate (get larger)
and glands secrete sweat.
• When temp drops below the set point,
dermal blood vessels constrict (get
smaller) and glands become inactive.
WHAT TYPE OF FEEDBACK IS THIS?
Healing of Wounds
• Skin injuries trigger inflammation; blood
vessels dilate and become more permeable,
forcing fluids to leave the blood vessels and
enter the damaged tissues.
WHAT TYPE OF FEEDBACK IS THIS?
• Dilated blood vessels supply the damaged
cells with more oxygen and nutrients; this
speeds healing.
• More platelets are supplied to clot blood.
• More white blood cells needed to fight
infection.
Page 170-1
Skin cancer
• There are three main types of skin cancer; basal cell
carcinoma, melanoma, and squamous cell
carcinoma.
• Both UVA and UVB contribute to skin cancer.
• Basal cell carcinoma is the most prevalent affecting
over 2 million Americans a year.
• Basal cell carcinoma develops in the cells of the
basement membrane typically due to sun exposure.
Melanoma
• Melanoma is the most deadly form of skin cancer
while also being the most rare.
• 120,000 new cases are diagnosed in the U.S. each
year.
• If caught early it is usually treatable, however if it
spreads to other parts of the body treatment becomes
much more difficult.
• Melanoma develops in the melanocytes located in
the epidermis.
• Melanoma usually appears black or brown.
Squamous cell carcinoma
• Squamous cell carcinoma is the second
most prevalent type of skin cancer.
• It originates in squamous cells of the
epidermis.
• It is more prevalent in areas exposed to the
sun and in people with lighter skin.
• Twice as many men as women develop this
type of skin cancer.
• http://www.skincancer.org/skin-cancer-video.html