Integumentary - Anaphy Lab

• Integumentary System - consists of the skin and accessory glands (hair, nails and cutaneous glands)
• Skin is the most vulnerable organ since it is exposed to radiation, trauma, infection and injurious chemicals
• Integumentary system receives more medical treatment than any other organ system
• Dermatology - scientific study and medical treatment of the integumentary system
• Skin is the body's largest and heaviest organ
• Layers of Skin

  1. Epidermis
  2. Dermis
  3. Hypodermis (not part of the skin, but associated)
• Thick skin covers front of hands and bottoms of feet and it has sweat glands, but no hair follicles or sebaceous glands
• Thin skin covers rest of the body that possess hair follicles, sebaceous glands and sweat glands
• Epidermis

  • keratinized stratified squamous epithelium
  • includes dead cells at skin surface packed with tough keratin prortein
  • Lacks blood vessels since it depends on the diffusion of nutrients from underlying connective tissue
  • Contains sparse nerve endings for touch and pain
• Five Epidermal Cell Types

  1. Stem Cells
  2. Keratinocytes
  3. Melanocytes
  4. Tactile cells
  5. Dendritic cells
• Epidermal Cell Type

  Stem Cell - undifferentiated cells that give rise to keratinocytes and found in the stratum basale
• Epidermal Cell Type

  Keratinocytes - great majority of epidermal cells that synthesize keratin
• Melanocytes - synthesize pigment melanin that shields DNA from UV radiation and occur only in stratum basale but have branched processes that spread among keratinocytes and distribute melanin
• Tactile cells - touch receptor cells associated with dermal nerve fibers found in basal layer of epidermis
• Dendritic cells - macrophages originating in bone marrow that guard against pathogens which are found in stratum spinosum and granulosum
• Layers of Epidermis (deepest to surface - BSGLC)

  1. basale
  2. Spinosum
  3. Granulosum
  4. Lucidum
  5. Corneum
• Thin skin contains four strata, thick skin contains five
• Basale

  • a single layer of stem cells and keratinocytes resting on the basement memrbane
  • stem cells divide and give rise to keratinocytes that migrate toward skin sufrace to replace lost cells
  • also contains a few melanocytes and tactile cells
• spinosum

  • several layers of keratinocytes joined together by desmosomes and tight junctions
  • named for appearance of cells after histological preparation (spiny)
  • also contains some dendritic cells
• granulosum

  • three to five layers of flat keratinocytes
  • cells contain dark-staining keratohyalin granules
• lucidum

  • thin, pale layer found only in thick skin
  • keratinocytes packed with clear protein eleidin
• stratum corneum

  • several layers of dead, scaly, keratinized cells
  • resists abrasion, penetration, water loss
• Dermis

  • connective tissue layer beneath epidermis
  • composed mainly of collagen
  • well-supplied with blood vessels, sweat glands, sebaceous glands and nerve endings
  • houses hair follicles and nail roots
  • the tissue of the facial skin to which skeletal muscles attach and cause facial expressions of emotion
  • has a wavy, conspicuous boundary with the superficial epidermis
• dermal papillae - upward, finger-like extensions of dermis
• epidermal ridges - downward waves of epidermis
• Two Layers of Dermis

  1. Papillary
  2. Reticular
• Papillary

  • superficial zone of dermis
  • thin zone of areolar tissue in and near the dermal papilla
  • allows for mobility of leukocytes and other defense cells
  • rich in small blood vessels
• reticular

  • deeper and thicker layer of dermis
  • consist of dense, irregular connective tissue
• Stretch marks (striae) - tears in the collagen fibers caused by stretching of the skin due to pregnancy or obesity
• hypodermis

  • subcutaneous tissue
  • has more areolar and adipose than dermis has
  • pads body and binds skin to underlying tissues
  • common site of drug injection since it has many blood vessels
• melanin - most significant factor in skin color which is produced by melanocytes that accumulates in keratinocytes
• Forms of Melanin

  1. Eumelanin - brownish black
  2. Pheomelanin - reddish yellow (suflur-containing)
• hemoglobin - pigment in red blood cells which adds reddish to pinkish hue on skin
• carotene - yellow pigment acquired from egg yolks and yellow/orange vegetables which concentrates in stratum corneum and subcutaneous fat
• Colors of Diagnostic Value

  1. Cyanosis - blueness due to oxygen deficiency
  2. Erythema - redness due to increased blood flow to skin
  3. Pallor - paleness due to decreased blood flow to skin
  4. Albinism - milky white skin and blue-gray eyes due to genetic lack of melanin synthesizing enzyme
  5. Jaundice - yellowing due to bilirubin in blood
  6. Hematoma - bruising
• Skin Markings

  Friction ridges

  • markings on the fingertips that leave oily fingerprints on surfaces we touch
  • allow manipulation of small objects
• flexion lines (flexion creases)

  • lines of the flexor surfaces of the digits, palms, wrists, elbows
  • mark sites where skin folds during flexion of joints
  • skin bound to deeper tissues along these lines
• freckles - flat, melanized patches

  moles (nevi) - elevated, melanized patches often with hair
• hemangiomas (birthmarks)

  • patches of discolored skin caused by benign tumors of dermal capillaries
• Hair

  • also named as pilus or pili
  • a slender filament of keratinized cells growing from a tube in the skin called hair follicle
  • it covers most of the body