Integumentary system

• Integumentary system-

  The skin and accessory structures, such as hair, glands, and nails
• Integumentary system


  • The appearance can indicate physiological imbalances in the body
• Integumentary system functions


  • Protection
  • Sensation
  • Vitamin D production
  • Temperature regulation
  • Excretion
• Epidermis


  The most superficial layer of skin, a layer of epithelial tissue that rests on the dermis
• Dermis


  A layer of dense connective tissue
• Subcutaneous tissue


  A layer of connective tissue, not part of the skin
• Epidermis


  • Prevents water loss and resists abrasion
  • Composed of distinct layers called strata
• Stratum corneum


  The most superficial stratum of the epidermis, consists of dead squamous cells filled with keratin
• Dandruff


  Excessive sloughing of stratum corneum cells from the surface of the scalp
• Callus


  A thickened area of the stratum corneum in skin subjected to friction
• Corn


  A cone-shaped thickening of the stratum corneum over a bony prominence
• Dermis


  • Composed of dense collagenous connective tissue
  • Contains nerves, hair follicles, smooth muscles, glands, and lymphatic vessels
  • Collagen and elastic fibers provide structural strength and resistance to stretch
• Cleavage lines


  Lines in the skin that are more resistant to stretch
• Dermal papillae


  Projections toward the epidermis found in the upper part of the dermis, contain blood vessels
• Factors determining skin color


  • Pigments in the skin
  • Blood circulating through the skin
  • Thickness of the stratum corneum
• Melanin


  The group of pigments primarily responsible for skin, hair, and eye color
• Melanin transfer to epithelial cells


  1. Melanin is produced by melanocytes and packaged into melanosomes, which move into the cell processes of melanocytes

  2. Epithelial cells phagocytize the tips of the melanocyte cell processes, acquiring melanosomes
• Albinism


  A genetic condition that prevents the production of melanin
• Carotene


  A yellow pigment found in plants that can accumulate in the skin and cause a yellowish appearance
• Cyanosis


  A bluish color of the skin due to a decrease in the blood O2 content
• Subcutaneous tissue


  Loose connective tissue that includes adipose tissue, attaches the skin to underlying bone and muscle, and supplies it with blood vessels and nerves
• Subcutaneous tissue


  • The amount and location of adipose tissue vary with age, sex, and diet
  • Can be used to estimate total body fat
• Hair follicle


  An invagination of the epidermis that extends deep into the dermis, where each hair arises from
• Hair shaft


  The part of the hair that protrudes above the surface of the skin
• Hair root


  The part of the hair below the surface of the skin
• Hair bulb


  The expanded base of the hair root
• Hair cortex


  The hard outer layer of the hair
• Hair medulla


  The softer center of the hair
• Hair cuticle


  A single layer of overlapping cells that holds the hair in the hair follicle
• Hair papilla


  An extension of the dermis that protrudes into the hair bulb and contains blood vessels
• Hair growth cycle

  1. Growth stage: hair is formed by mitosis of epithelial cells within the hair bulb

  2. Resting stage: growth stops and the hair is held in the hair follicle
• Arrector pili muscle


  Smooth muscle cells attached to each hair follicle that can contract and cause the hair to become perpendicular to the skin's surface
• Sebaceous glands


  Simple, branched acinar glands that produce sebum, an oily, white substance rich in lipids
• Eccrine sweat glands


  Simple, coiled, tubular glands that release sweat by merocrine secretion, located in almost every part of the skin
• Apocrine sweat glands


  Simple, coiled, tubular glands that produce a thick secretion rich in organic substances, open into hair follicles in the armpits and genitalia
• Sebaceous glands


  Simple, branched acinar glands, with most being connected by a duct to the superficial part of a hair follicle
• Sebum


  An oily, white substance rich in lipids produced by sebaceous glands
• Sweat glands


  Two kinds: eccrine and apocrine
• Eccrine sweat glands


  Simple, coiled, tubular glands that release sweat by merocrine secretion
• Eccrine sweat glands


  • Located in almost every part of the skin but most numerous in the palms and soles
  • Produce a secretion that is mostly water with a few salts
  • Have ducts that open onto the surface of the skin through sweat pores and are for thermal regulation