BI 121 EXAM 2 Learning Objectives

• What are the six major functions of the skin?

  1. Protects underlying tissue and organs

  2. Excretes salts, water, and organic wastes(glands)

  3.Maintains Body Temperature (insulation and evaporative cooling)

  4.Synthesizes vitamin D3

  5.Stores lipids

  6. Detects touch, pressure, pain, and temperature.
• What two parts compose the integumentary system? Give examples of both parts.

  Cutaneous membrane

  -Epidermis

  Accessory Structures

  -Hair
• What are exocrine glands?

  Secrete their product into ducts.
• Compare and contrast the epidermis from the dermis in regard to tissue type, location, and vascularity.

  Both Cutaneous membraneEpidermis:(Top Layer)Epithelial Tissue-Outermost protective shield-AvascularDermis:(Lies beneath the epidermis)Connective Tissue-Tough leathery layer-Vascular
• Which layer, the epidermis or dermis, houses the accessory structures?

  The epidermis- Origin of accessory structures
• Where is the hypodermis (subcutaneous layer) located in regard to the integumentary system? What is its function?

  -Deep to the cutaneous layer,(the bottom layer of skin in your body.)-To stabilize and support integument
• The cells of the epidermis are called ____________.

  Keratinocytes
• What is the difference between thick and thin skin in regard to the number of layers of these cells.

  Think Skin4LayersThick Skin5Layers
• Differentiate the location of thick vs. thin skin on our bodies.


  Thin= Most of body

  Thick=Palms, fingertips and sole of feet.
• List the five strata, or layers, of keratinocytes in order from basal lamina to the apical (free) surface. From Deep to Superficial

  1.Stratum Basale

  2.Stratum Spinous

  3.Stratum granulosum

  4.Statum Lucidum

  5.Statum Coneum
• Also be able to list the five strata of keratinocytes in order from the apical surface to the basal lamina (i.e., the opposite direction).

  5.StatumConeum4.StatumLucidum3.StratumGranulosum2.StratumSpinous1.StratumBasaleComeLetGetSunBurned
• What are Melanocytes and what stratum are they found in?

  Pigment

  Found in Stratum Basale
• What stratum is produced by having the stratum basale divide?

  Stratum spinous
• What stratum stops dividing and begins keratinization?

  Stratum Granulosum
• What is keratinization?

  formation of a superficial layer of dead, tough, protective cells filled with keratin
• What stratum is present in thick skin but not thin skin?

  Stratum Lucidum- Present only in Thick Skin
• What stratum is the exposed surface of the skin?

  stratum corneum
• What is the usual length of time for a cell to move from the stratum basale to the stratum corneum?

  7 days, then 2 weeks
• What pigment really influences skin color?

  melanin
• What cells produce the pigment?

  melanocytes
• Do people with darker skin have more of these cells?

  No, everybody approximately have the same number of melanocytes
• What stratum do you find these cells in?

  stratum basale
• Besides pigments, what other factor influences skin color?

  Degree of dermal blood circulation (red blood cells)
• What is albinism and vitiligo?

  No melanin production

  Melanocytes in certain areas lose their ability to produce melanin.
• What functions does melanin serve?

  protects epidermal cells from UV radiation
• What vitamin is synthesized by UV radiation?

  Vitamin D
• The liver and kidney convert this vitamin into calcitriol - what is calcitriol's function?

  Aids absorption of calcium
• What would happen without the presence of calcitriol?

  You won't be able to get calcium into your body.
• What condition is caused by insufficient Vitamin D?

  Rickets
• What two layers compose the dermis?

  papillary layer (20%) and reticular layer (80%)
• Which one of these layers contains the capillaries and nerves that serve the epidermis?

  Papillary Layer
• What is the function of a hair follicle?

  surrounds and produces non-living hair
• What muscles and glands are associated with hair?

  arrector pili muscle (goosebumps)
• What is the function of hair?

  protection, reduction of heat loss, sense light touch
• What is the anatomical name for oil gland?

  sebaceous gland
• What about sweat gland?

  Sudoriferous gland
• What gland produces sebum and what is the function of sebum?

  sebaceous gland, inhibits bacterial and fungi growth
• Contrast eccrine with apocrine sweat glands.

  Eccrine- thermoregulation, waste removal, active through out life, all over skin.

  Apocrine-Sexual excitement, active during puberty"cold sweat", and limited distribution.
• What are the functions of nails and what are they composed of?

  -protect fingers and toes

  -Dead epidermal cells packed with keratin.
• Understand the effects of aging on the integument.

  Epidermal and dermal thinning, decreased melanocyte activity, increased risk of infection and sun damage, slower skin repair, decreased vitamin D3 synthesis, diminished blood supply, and decreased glandular activity (sweat and sebaceous glands).