Chapter 4: Integumentary System

• Skin - keeps water and essential molecules in our body, and also keeps out harmful substances out
• Skin's appendages:

  • Sweat and Oil
  • Glands
  • Hair
  • Nails
• Integumentary System - protects the body from the environment and is made up of the skin, hair, nails, and mucous membranes
• Body Membrane - cover surfaces, line body cavities, and form protetive sheets around organs
• Two major body membranes:

  • Epithelial Membrane
  • Connective Tissue Membrane
• Epithelial Membrane - also called covering and lining membranes, include the cutaneous (skin), mucous, and the serous membrane
• Cutaneous Membrane - The outermost layer of the body, consisting of the epidermis and dermis
• Mucous Membrane - lines all body cavities that open to the exterior, such a those of the hollow organs
• Serous Membrane - lines body cavities that are closed to the exterior
• Parietal layer - lines a specific portion of the wall of the ventral body cavity
• Visceral layer - covers the outside of the organ
• Serous Fluid - separates the serous layers; a scanty amount of thin, clear fluid
• Peritoneum - serosa lining the abdominal cavity and covering its organs
• Pericardia - isolates the heart; membrane that covers the heart
• Synovial Membrane - A thin layer of connective tissue that lines the joint cavity
• Functions of the Integumentary System:

  • Mechanical Damage
  • Chemical Damage
  • Microbe Damage
  • Ultraviolet radiation
  • Aids in heat loss and retention
  • Aids in excretion of urea and uric acid
  • Synthesizes vitamin D
• Acid Mantle - produced by the skin that protect against bacterial invasion
• Epidermis - the outer part of the skin that is made up of stratified squamous epithelium, capable of becoming hard and tough
• Dermis - underlying part which is made up of dense connective tissue
• Subcutaneous - under the skin, fatty tissue, and connective tissue
• subcutaneous - site for nutrient storage, serves as a shock absorber
• Keratinocytes - produces keratin that makes up the tough part of the skin through the process of keratinization
• Five Layers of Epidermis

  • Stratum Corneum
  • Stratum Granulosum
  • Stratum Spinosum
  • Stratum Basale
• Stratum Basale - the deepest layer of the epidermis, where stem cells constantly divides
• Stratum Spinosum - where cells contains thunk bundles of filaments made of pre-keratin are found
• Stratum Granulosum - where cells are flattened and organelles are deteriorating; cytoplasm is now full of GRANULES
• Stratum Corneum - where cells are dead, flat and filled with keratin; is water resistant
• Stratum Lucidum - only found where skin is hairless and extra think; palms of the hands, and soles of the feet
• Melanin - pigment that absorbs light and gives skin its color; produced by melanocytes
• Merkel Cells - sensory nerve endings and serve as touch receptors
• Two Major Regions of the Dermis

  • Papillary Layer
  • Reticular Layer
• Papillary Layer - superficial dermal region, and has a peglike projections that indent the epidermis above
• Finger-prints - unique, identifying films of the hand
• Reticular Layer - deepest skin layer; contains dense irregular connective tissue
• Three Pigments of the Skin

  • Melanin - yellow, reddish brown, or black, and was produced due to sunlight
  • Carotene - orange-yellow pigment
  • Hemoglobin - pigment in red blood cells
• Cutaneous Glands - exocrine glands that release secretion to the skin through ducts
• Two Groups of Cutaneous Glands

  • Sebaceous Glands
  • Sweat Glands
• Sebaceous Glands - Secrete sebum, which is an oily substance that lubricates the skin and hair
• Sweat Glands - secrete sweat which is a mixture of water, salt, urea and other substances
• Apocrine Glands - glands that are confined to the axillary and genital areas