Integumentary System

Human Anatomy, First Edition
McKinley & O'Loughlin
Chapter 5 Lecture Outline:
Integumentary System
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The Integument
• The skin that covers your body.
• Skin is also known as the cutaneous
membrane.
• Integumentary system consists of the
skin and its derivatives—nails, hair,
sweat glands, and sebaceous glands.
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The Integument
• Is the body’s largest organ.
• Its surface is covered by an epithelium that protects
underlying body layers.
• The connective tissues contain blood vessels that
provide nutrients and provide strength and resilience
to the skin.
• Smooth muscle controls both blood vessel diameter
and hair position.
• Neural tissue supports and monitors sensory
receptors in the skin
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2 Distinct Layers
• A layer of stratified squamous
epithelium called the epidermis.
• A deeper layer of dense irregular
connective tissue called the dermis.
• deep to the dermis is a layer of areolar and
adipose connective tissue called the
subcutaneous layer, or hypodermis
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Thick Skin
• Thick epidermis is found on the palms
of the hands, the soles of the feet, and
corresponding surfaces of the fingers
and toes.
• All five epidermal strata occur in thick
skin.
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Thin Skin
• Thin epidermis covers most of the body.
• Lacks the stratum lucidum
• Has only four specific layers.
• Contains the following accessories: hair
follicles, sebaceous glands, and sweat
glands.
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Functions of Skin
• protection
• prevention of water loss
• temperature regulation
• metabolic regulation
• immune defense
• sensory reception
• excretion
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Skin Color
• Hemoglobin is an oxygen-binding protein
present in red blood cells. Upon binding with
oxygen, hemoglobin exhibits a bright red
color.
• Melanin is a pigment produced and stored in
cells called melanocytes.
• the two types of melanin occur in various yellow,
reddish, tan, brown, and black shades
• Carotene comes primarily from diet.
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Friction Ridges
• Found on the fingers, palms, soles, and toes.
• Formed from large folds and valleys of both
dermal and epidermal tissue.
• Help us grasp objects, and they
• Increase friction so that items do not slip
easily from our hands.
• Our feet do not slip on the floor when we
walk.
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Friction Ridges
• Friction ridges can leave noticeable
prints on touched surfaces.
• Each individual has a unique pattern of
friction ridges.
• Fingerprints have become a valuable
tool for law enforcement in identifying
individuals.
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Skin Markings
• Nevus (mole)
• Freckles
• Hemangioma
• capillary hemangiomas (“strawberrycolored
birthmarks”)
• cavernous hemangiomas (“port-wine
stains”)
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Layers of the Dermis
• Composed of cells of the connective
tissue proper and primarily of collagen
fibers, although both elastic and
reticular fibers are also present.
• Other components of the dermis are
blood vessels, sweat glands, sebaceous
glands, hair follicles, nail roots, sensory
nerve endings, and muscular tissue.
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2 Major Regions of Dermis
• Superficial papillary layer
• Deeper reticular layer
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Lines of Cleavage
• Tension lines in the skin identify the
predominant orientation of collagen fiber
bundles.
• Clinically and surgically significant because
cuts can result in slow healing and increased
scarring.
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Innervation and Blood Supply
• The dermis has extensive innervation.
• Monitor sensory receptors in the dermis and
epidermis, and control both blood flow and gland
secretion rates.
• Tactile corpuscles and tactile (Merkel) cells perceive
touch sensations, and work with a variety of other
sensory nerve endings in the skin.
• This rich innervation allows us to be very aware of
our surroundings and to differentiate among the
different kinds of sensory signals from receptors in
the skin.
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Nails
• Scalelike modifications of the epidermis
that form on the dorsal surfaces of the
tips of the fingers and toes.
• Protect the exposed distal tips and
prevent damage or distortion during
jumping, kicking, catching, or grasping.
• Hard derivatives formed from the
stratum corneum layer of the epidermis.
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Hair
• Found almost everywhere on the body
except the palms of the hands, the
sides and soles of the feet, the lips, the
sides of the fingers and toes, and
portions of the external genitalia.
• Most of the hairs on the human body
are on the general body surface rather
than the head.
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3 Kinds of Hair
• During our lives, we produce three
kinds of hair:
• lanugo
• vellus
• terminal hair
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Functions of Hair
• Protection
• Heat retention
• Prevents the loss of conducted heat from the
scalp to the surrounding air
• Facial expression
• Sensory reception
• Visual identification
• Chemical signal dispersal
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Hair Color
• Result of the synthesis of melanin in the
matrix adjacent to the papillae.
• Variations in hair color reflect genetically
determined differences in the structure of the
melanin.
• Environmental and hormonal factors
• Age
• Gray hair
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Hair Growth and Replacement
• Sometimes hair loss may be temporary
as a result of one or more of the
following factors: exposure to drugs,
dietary factors, radiation, high fever, or
stress.
• Thinning of the hair, called alopecia can
occur in both sexes, usually as a result
of aging.
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Exocrine Glands of the Skin
• Sweat (sudoriferous) glands produce a
watery solution that performs several
specific functions.
• merocrine (eccrine) sweat glands
• apocrine sweat glands
• Sebaceous glands produce an oily material
that coats hair shafts and the epidermal
surface.
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Other Integumentary Glands
• Ceruminous glands
• Mammary glands
• modified apocrine sweat glands
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Burns
• Major cause of accidental death, primarily as
a result of their effects on the skin.
• Usually caused by heat, radiation, harmful
chemicals, sunlight, or electrical shock.
• The immediate threat to life results primarily
from fluid loss, infection, and the effects of
burned, dead tissue.
• Burns are classified according to the depth of
tissue involvement.
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Classification of Burns
• First- and second-degree burns are
called partial-thickness burns.
• Third-degree burns are called fullthickness
burns.
• first-degree burns involve only the
epidermis and are characterized by
redness, pain, and slight edema
• an example is sunburn
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Classification of Burns
• Second-degree burns involve the
epidermis and part of the dermis.
• The skin appears red, tan, or white, and
is blistered and painful.
• An example is a scald.
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Classification of Burns
• Third-degree burns involve the epidermis, dermis,
and subcutaneous layer, which are often destroyed.
• Regeneration may occur from the edge only, due to
the absence of dermis.
• Skin grafting is required to prevent abnormal
connective tissue fibrosis and disfigurement.
• Dehydration is a major concern because the entire
portion of skin has been lost, and water cannot be
retained.
• Must be aggressively treated for dehydration.
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Aging of the Integument
• Skin repair processes take longer due to
reduced number and activity of stem cells.
• Skin forms wrinkles and becomes less
resilient.
• Skin’s immune responsiveness is diminished.
• Skin becomes drier due to decreased
sebaceous gland activity.
• Altered skin and hair pigmentation.
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Aging of the Integument
• Sweat production diminishes.
• Blood supply to the dermis is reduced
leading to impaired thermoregulation.
• Hair thinning and loss.
• Integumentary production of vitamin D 3
diminishes.
• Development of skin cancers.
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Skin Cancer
• The most common type of cancer.
• The greatest risk factor is exposure to
UV rays of the sun.
• The highest incidence is in people who
have had severe sunburns, especially as
children.
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