Introduction (1)

• The largest organ in the body is the skin.
• Integumentary System

  • From the Latin word "Integumentum” which means a covering; and
  • French word “intego” which means to cover.
• Integumentary System

  • From the Latin word "Integumentum” which means a covering; and
  • French word “intego” which means to cover.
• Together with the hair, nails, glands, breast, and the skin constitutes the integumentary system.
• FUNCTIONS OF THE INTEGUMENTARY SYSTEM:

  
  

  The skin

  • protects against bacterial invasion
  • reservoir for food and water
  • sensory receptor synthesis of vitamin D
  • regulate body temperature and water
  • prevents dehydration
• STRUCTURES OF THE SKIN

  • Epidermis
  • Dermis
  • Subcutaneous Tissues
• Squamous is derived from the Latin term for the scale of a fish or serpent, squama. It is used in anatomy to describe thin, flat-like or scalelike structures, i.e squamous tissue.
• Epidermis

  • the outermost layer of the skin.
  • It is composed of avascular (without a direct blood supply) tissue.
  • It is a squamous tissue that is arranged in several strata or sublayers called stratified squamous epithelium.
  • The most important of the four or five sublayers are the stratum corneum and the stratum germinativum.
• Stratum Basale/Germinativum

  The stratum germinativum or the basal cell layer is the deepest layer of the epidermis where new cells are formed and produced to replace superficial keratized cells that are continuously shed away. It also contains specialized skin cells called melanocytes.
• Melanocytes are pigment producing cell in the basal layer of the epidermis that form and contain a black or dark brown pigment called melanin which gives color to the skin and which helps filter ultraviolet light.
• Stratum corneum is the outermost layer of the epidermis.
• As the cells from stratum germinativum layer move toward the stratum corneum, they die and become filled with a hard protein material called keratin.
• Dermis or the Corium is the middle layer of the skin lying immediately under the epidermis.

  
  

  It is composed of living tissue that interdigitates with the epidermis. Hair follicles, sebaceous (oil) glands, and sweat glands are also located in the dermis.
• Most of the dermis is made up of extracellular material called “Matrix”. Matrix contains connective tissue fibers including collagen, a structural protein (Kolla- glue + gennao – I produce) that gives strength to the dermis; elastin which makes the skin pliable; and reticular fibers which bind the collagen and elastin fibers together. The reticular fibers are produced by dermal fibroblasts, a spindle-shaped connective tissue cell.
• 2 Layers of the Dermis

  • Papillary
  • Reticular
• Reticular Dermis covers a layer of subcutaneous tissue, the adipose or panniculus adiposus, that is composed of fat cells. It insulates the body, provides energy and serves as mechanical shock absorber.
• Subcutaneous tissue (hypodermis) or Stratum subcutaneum is the innermost layer of the skin.

  
  

  It is an underlying connective tissue layer that contains fat or adipose tissue and connects the skin to underlying organs.

  
  

  It specializes in formation of fat. Adipose or fat cells provide a food reserve and insulation
• Appendages of the Skin or Accessory Structures of the Skin:

  • Hair
  • Sebaceous Gland
  • Sweat Glands or Sudoriferous Glands
  • Ceruminous Glands
  • Nail
  • Breast or Mammary Glands
• Hair - are long slender shaft composed of keratin.

  
  

  From the Latin word “pilus/pili” which means hair.
• Sebaceous glands are numerous holocrine glands which occur on all parts of the skin except the palms and sole. It secrete an oily semifluid sebum into the hair follicle via the sebaceous duct.
• Sweat glands or the Sudoriferous Glands – eccrine glands that secrete sweat with sodium concentration to enable evaporative cooling in a hot environment or in response to emotion.
• Ceruminous glands are modified sweat glands located in ear canals cerumen
• Nails are specialized type of keratin.
• Nails (Accesory Structure of the Skin)

  A) horny layer of epidermis

  B) cuticle

  C) nail plate

  D) nail matrix

  
• The mammary glands are located in the upper anterior aspect of the chest.
• Estrogen formed from the ovary is responsible for the adipose tissue and increased size of the breasts during puberty.
• Progesterone forms the lobules that are present in the breast.
• Areola is a circular pigmented area which surrounds the nipple (papilla mamae). Its surface is dotted with little projections due to presence of areolar glands beneath.
• Parts of the nail:

  • Nailbed which covers the dorsal surface of the last bone of each finger.
  • Lunula is the crescent-shaped white area near the root of the nail bed. The lunula is the area in which new growth occurs.
• Medical term for nail originated from a Greek word onyx meaning nail.
• Onychomalacia means abnormal softening of the nail.
• Skin Layers

  A) Epidermis

  B) Dermis

  C) Hypodermis

  
• Stratum Basale or Stratum Germinativum

  
• Stratum Corneum

  
• The dermis