The skin has three layers - the epidermis, dermis, and subcutaneous tissue. The epidermis is the outermost layer and varies in thickness, while the dermis lies below and contains collagen, elastin, and fibers. The subcutaneous tissue acts as insulation. The skin functions to protect the body, sense stimuli, excrete waste, and regulate temperature. It protects against damage and pathogens, and contains sensory receptors. Through sweating and blood flow regulation, it also helps control body heat. Common disorders of the integumentary system include acne, eczema, fungal infections, and psoriasis.

1. Human Anatomy & Physiology

2.  IINNTTEEGGUUMMEENNTTAARRYY
SSYYSSTTEEMM

3.  Includes the skin
and its related
structures that
cover and protect
the body
 IINNTTEEGGUUMMEENNTTAARRYY
SSYYSSTTEEMM

4. Skin layers
Two distinct layers of skin, the epidermis and dermis, lie
above a third layer of subcutaneous tissue—sometimes
called the hypodermis.

5. Skin layers

6. Skin layers
Epidermis
Outermost layer
Composed epithelial tissue
Consists of five sublayers
Varies in thickness from less than 0.1 mm (on the eyelids)
to more than 1 mm (on the palms and soles)

7. EEppiiddeerrmmiiss

8. Contains and
supports blood
vessels, lymphatic
vessels, nerves, and
the epidermal
appendages
DDeerrmmiiss

9. Composed primarily of matrix, which
Contains collagen (gives strength),
Elastin (provides elasticity), and
Reticular fibers (bind collagen and
elastin fibers together)
Consists of two sublayers
DDeerrmmiiss
Papillary dermis
Reticular dermis

10. Papillary dermis
DDeerrmmiiss
Contains fingerlike projections (papillae)
that connect the dermis to the epidermis
Contains characteristic ridges
Reticular dermis
Covers a layer of subcutaneous tissue,
Insulating the body to conserve heat
Provides energy
Serves as a mechanical shock absorber

11. SSkkiinn ffuunnccttiioonnss
The integumentary system is the largest body
system. In addition to the skin, or integument , it
includes the hair, nails, and certain glands
Functions of Skin
Protection
Sensory Perception
Excretion
Body temperature

12. SSkkiinn ffuunnccttiioonnss Protection
Maintains the integrity of the body surface
(Through skin migration and shedding)
Repairs surface wounds
(by intensifying normal cell replacement)
Protects the body against noxious
chemicals and invasion from bacteria and
microorganisms
Contains melanocytes (which produce the brown
pigment melanin) that help filter ultraviolet light

13. SSkkiinn ffuunnccttiioonnss Sensory Perception
Contains sensory nerve fibers that supply specific
areas of the skin (dermatomes)
Allows for perception of temperature, touch,
pressure, pain, and itching
Contains autonomic nerve fibers that carry impulses
to smooth muscle

14. Sensory Perception

15. Excretion
SSkkiinn ffuunnccttiioonnss
Excretes sweat, which contains water,
electrolytes, urea, and lactic acid
Prevents dehydration by regulating the
content and volume of sweat
Prevents unwanted fluids in the
environment from entering the body

16. Body temperature
SSkkiinn ffuunnccttiioonnss
Contains nerves, blood vessels, and eccrine
glands within the skin's deeper layer to
control body temperature
Causes blood vessels to constrict (reducing
blood flow and conserving heat) when exposed
to cold or internal body temperature falls
Causes small arteries within the skin to
dilate (increasing the blood flow and
reducing body heat) when skin becomes too hot or
internal body temperature rises

17. The skin's role in thermoregulation
Time to warm up
The skin becomes exposed to cold, or internal
body temperature falls.
Blood vessels constrict in response to
stimuli from the autonomic nervous
system.
Blood flow decreases through the skin, and body heat
is conserved.

18. Now let's cool
Increased blood flow reduces body heat. If
this doesn't lower temperature, the sweat
glands act to increase sweat production,
and evaporation cools the skin.
Small arteries in the
second skin layer
(dermis) dilate (expand).

19. Disorders of the Integumentary System
• Acne vulgaris
– Caused by increased secretion of oil related to
increased hormones during puberty
• Albinism
– Inherited disorder in which melanin is not produced
• Alopecia
– Baldness
• Athlete’s foot
– Contagious fungal infection of the foot

20. • Cellulitis
– Bacterial infection of the dermis and subcutaneous
layer of the skin
• Chloasma
– Patchy discoloration of the face
• Contact dermatitis
– Allergic reaction that may occur after initial contact or
as an acquired response

21. • Dandruff
– White flakes of dead skin cells from the scalp
• Decubitus ulcers
– Sores or areas of inflammation that occur over bony
prominences of the body
• Eczema
– Group of disorders caused by allergic or irritant reactions
• Fungal skin infections
Skin infections that live on dead outer surface or epidermis

22. • Furuncle
– Boil, or bacterial infection of a hair follicle
• Impetigo
– Very contagious bacterial skin infection that occurs most
often in children
• Psoriasis
– Chronic skin disorder in which too many epidermal cells are
produced
• Rashes
– May result from viral infection, especially in children

23. – Vitiligo
– Condition that causes loss of pigment in the skin
– Wart
– Papule caused by a viral infection

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