Human Anatomy, First Edition McKinley

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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
  derivativesnails, hair, sweat glands, and
  sebaceous glands.

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The Integument

• Is the bodys 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.
• Skins 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.