integumentary system

• Integumentary system

  The body system that forms the body's outer covering and primarily functions in protecting the body from the threats of outside environment
• Integumentary system

  • Composed of the skin and its derivatives: the hairs, nails, and glands

  
• Functions of the integumentary system

  • Protection
  • Covering
  • Sensation
  • Thermoregulation
  • Vitamin D synthesis
  • Excretion
  • Osmoregulation
• Skin


  The largest external organ of the body
• Epidermis


  The outermost layer of the skin

  
• Layers of the epidermis

  • Stratum Corneum
  • Stratum Lucidum
  • Stratum Granulosum
  • Stratum Spinosum
  • Stratum Basale

  
• Stratum Corneum


  Uppermost multi-layer of dead, keratinized, cornified squamous cells
• Exfoliation


  The process of the stratum corneum continuously shedding off dead cells
• Stratum Lucidum


  Only found in thick skin (skin found in the palms of hands and soles of feet), provides additional thickness to these areas which are prone to shock and pressure

  
• Stratum Granulosum


  Has active keratinocytes, which are cells producing keratin
• Stratum Spinosum

  Composed of spiny-shaped cells, contributes to the strength and flexibility of the skin
• Stratum Basale


  Lowermost layer made up of one layer of columnar cells, mitosis layer where cells are actively dividing giving rise to cells which will later comprise the upper layers, contains melanocytes which produce melanin
• Melanin


  Substance responsible for skin pigmentation, acts as protection against harmful UV rays
• Dermis


  The second layer of the skin found between the epidermis and hypodermis, acts as the skin glue

  
• Functions of the dermis

  • Provides elasticity of the skin
  • Nourishes the epidermis
  • Receives sensory stimulation
  • Forms the unchanging fingerprint and footprint for unique identity and for easy grasping without slippage
• Structures found in the dermis

  • Abundant Areolar Connective Tissue
  • Blood Vessels
  • Sensory Receptors
  • Follicles and Glands
• Hypodermis/Subcutaneous


  The lowermost layer of the skin made up of fats and adipose tissue, found between the dermis and muscle

  
• Functions of the hypodermis

  • Provides a high energy reserve
  • Provides insulation
  • Provides cushion
  • Gives body contour
• Hair


  Structure produced by the basale cells of the skin, made up of keratin and cuticle

  
• Functions of hair

  • Thermoregulation
  • Protection
  • Sensation
• Nails


  Thin, hard covering at the tips of fingers and toes made up of cuticle and keratin
• Functions of nails


  • Provides protection to the toes and fingers
  • Used in grasping small objects
  • Provides protection (modified defensive structures such as claws)
  • May reflect abnormalities in the body when there are changes in the color, shape, thickness, or texture
• Glands


  Structures embedded in the dermis of the skin which secrete various substances
• Types of skin glands

  • Sebaceous gland
  • Sweat gland
• Nail structure

  • Nail plate (body)
  • Nail fold (root)
• Glands


  Structures embedded in the dermis of the skin which secrete various substances aiding in some of the functions of the skin
• Types of skin glands

  • Sebaceous gland
  • Sweat gland
• Sebaceous glands


  Sac-like type of exocrine gland whose duct opens into the hair and out in the skin surface, secreting oil or sebum
• Functions of sebum


  Lubricates the skin and hair, prevents dryness, and contributes to the acidity of the skin which makes the organ an unsuitable place for the growth of pathogens and microorganisms
• Meibomian glands


  Modified sebaceous glands found in the eyelids, secreting oil to lubricate eyelashes
• Sweat glands


  Coiled tubule-like type of exocrine gland whose duct opens into the skin surface, secreting sweat (a mixture of water, ions, nitrogenous wastes and sometimes proteins)
• Types of sweat glands

  • Eccrine sweat gland
  • Apocrine sweat gland
• Eccrine sweat glands


  Found almost everywhere, secreting mainly water, some NaCl, very small amounts of urea, uric acid, and potassium, functioning for thermoregulation and minor excretion
• Apocrine sweat glands


  Found only on some areas such as the armpit and ano-genital area, active during puberty, emotional stress, and sexual stimulation, secreting water, proteins and amino acids, contributing to body odor if left unchecked
• Other modified sweat glands

  • Ceruminous glands (secrete earwax)
  • Ciliary glands (secrete tear-like substance)
  • Mammary glands (secrete milk)
• Skin aging depends on a variety of factors such as lifestyle, diet, genes, and personal habits such as smoking and alcohol drinking. Exposure to the sun, pollution, stress, and even obesity hastens the aging of the skin.
• Structural and physiological changes in the skin as we grow older

  • Becomes rougher and drier due to the loss of cuticle in the surface
  • May develop benign tumors and lesions
  • Becomes slack or soggy due to the loss of elastin fibers in the connective tissue of the dermis
  • Becomes more transparent due to the thinning of the layers of the epidermis
  • Becomes more fragile due to the continuous death of the connective tissue in the dermis
  • Becomes more easily bruised due to the thinning on the walls of the skin blood vessels in the dermis
  • Losses fat in the hypodermal region particularly in body areas such as cheeks, temples, chin, nose, and eye
  • Develops discoloration due to the decline in the activity of the melanocytes
  • Hair becomes gray as it enters the late phase of its life cycle (telogen)

  
• Skin care tips

  • Carefully wash your skin with soaps which do not contain harsh substances
  • Regularly cleanse your skin using products which are suitable to your skin nature and needs
  • Use sunscreens if doing field work or out in the sun
  • Avoid sun exposure during 10 AM- 2 PM
  • Control hypertension and diabetes
  • Avoid smoking
  • Regularly exercise including face exercises and body massage
  • Always have an adequate sleep
  • Take supplements, minerals, vitamins, anti-oxidants for a healthier skin
• Sensory receptors are grouped into mechanoreceptors (physical deformation), thermoreceptors (heat/cold), and pain receptors/noireceptors (harmful conditions)
• Vitamin D synthesis goes from cholecalciferol, to calcidol, to calcitrol, which is used for absorption and bone nourishment.