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Human Anatomy, First EditionMcKinley & 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 (“strawberry-colored 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 full-

thickness 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

D3 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.