Skin System Powerpoint

• Body membranes


  • Cover body surfaces
  • Line body cavities
  • Form protective sheets around organs
• Types of body membranes

  • Epithelial membranes
  • Connective tissue membranes
• Epithelial membranes


  • Cutaneous membranes
  • Mucous membranes
  • Serous membranes
• Epithelial membranes


  Simple organs containing both an epithelial tissue layer and a connective tissue layer
• Cutaneous membrane


  Skin, a dry membrane that is the outermost protective boundary

  
• Cutaneous membrane


  • Consists of two layers: epidermis (keratinized stratified squamous epithelium) and dermis (mostly dense connective tissue)
• Mucous membranes (mucosae)


  Moist membranes that line body cavities open to the exterior, adapted for absorption or secretion
• Mucous membranes


  • Consist of an epithelium layer and a loose connective tissue layer (lamina propria)
• Serous membranes (serosae)


  Line compartments in the ventral body cavity that are closed to the exterior
• Serous membranes


  • Occur in pairs, separated by serous fluid, with a visceral and parietal layer, consisting of a simple squamous epithelium and areolar connective tissue
• Specific serous membranes


  • Peritoneum (covers abdominal organs)
  • Pleurae (surround the lungs)
  • Pericardium (surround the heart)
• Synovial membranes


  Loose areolar connective tissue that lines fibrous capsules surrounding joints, bursae, and tendon sheaths, secreting a lubricating fluid
• Integumentary system


  Consists of the skin (cutaneous membrane) and skin appendages (sweat glands, oil glands, hair, nails)

  
• Functions of the integumentary system

  • Insulates and cushions deeper organs
  • Protects from mechanical, chemical, thermal, UV, and microbial damage
  • Regulates heat loss
  • Aids in excretion
  • Synthesizes vitamin D
  • Creates a protective acid mantle
• Skin


  • Composed of two main tissues: epidermis and dermis, with a subcutaneous layer (hypodermis) that anchors the skin

  
• Epidermis


  Outer layer of the skin, composed of stratified squamous epithelium with keratinocytes that produce keratin
• Layers of the epidermis

  • Stratum basale
  • Stratum spinosum
  • Stratum granulosum
  • Stratum lucidum (thick skin only)
  • Stratum corneum
• Melanin


  Pigment produced by melanocytes in the stratum basale, contributing to skin color
• Dermis


  Connective tissue layer underlying the epidermis, with a papillary layer and a reticular layer
• Papillary layer of dermis

  • Contains areolar connective tissue, dermal papillae that indent the epidermis, capillary loops, and sensory receptors
• Reticular layer of dermis


  • Contains dense irregular connective tissue, blood vessels, glands, and deep pressure receptors
• Pigments contributing to skin color

  • Melanin
  • Carotene
  • Hemoglobin
• Skin appendages


  Cutaneous glands (sebaceous and sweat glands), hair and hair follicles, nails
• Sebaceous (oil) glands


  Produce sebum to make skin soft and moist, prevent hair brittleness, and kill bacteria
• Types of sweat glands

  • Eccrine glands
  • Apocrine glands
• Eccrine sweat glands


  More numerous, located all over the body, produce acidic sweat for body temperature regulation
• Apocrine sweat glands


  Ducts empty into hair follicles in armpits and genitals, begin functioning at puberty, produce sweat with fatty acids and proteins
• Hair


  Produced by hair follicles, consists of keratinized epithelial cells, with melanocytes providing pigment
• Eccrine glands


  • More numerous, located all over the body
  • Open via duct to sweat pores on the skin's surface
  • Produce acidic sweat (water, salts, vitamin C, traces of metabolic waste)
  • Function in body temperature regulation
• Apocrine glands


  • Ducts empty into hair follicles in the armpit and genitals
  • Begin to function at puberty
  • Release sweat that also contains fatty acids and proteins (milky or yellowish color)
  • Play a minimal role in body temperature regulation
• Hair


  • Located body-wide except for palms, soles, lips
  • Produced by hair follicle
  • Root is enclosed in the follicle
  • Shaft projects from the surface of the scalp or skin
  • Consists of hard keratinized epithelial cells
  • Melanocytes provide pigment for hair color
  • Hair grows in the matrix of the hair bulb in stratum basale
• Hair anatomy


  • Central medulla
  • Cortex surrounds medulla
  • Cuticle on outside of cortex (most heavily keratinized region of the hair)
  • Melanin provides color
• Hair follicle


  • Composed of an inner epithelial root sheath and an outer fibrous sheath
  • Dermal region provides a blood supply to the hair bulb (deepest part of the follicle)
  • Arrector pili muscle connects to the hair follicle to pull hairs upright when we are cold or frightened
• Nails


  • Heavily keratinized, scalelike modifications of the epidermis
  • Stratum basale extends beneath the nail bed, which is responsible for growth
  • Lack of pigment makes nails colorless
• Parts of a nail


  • Free edge
  • Body is the visible attached portion
  • Nail folds are skin folds that overlap the edges of the nail; the cuticle is the proximal edge
  • Root of nail is embedded in skin
  • Growth of the nail occurs from nail matrix of nail bed
• Athlete's foot


  • Caused by fungal infection (Tinea pedis)
  • Itchy, red peeling skin between the toes
• Boils (furuncles) and carbuncles

  • Caused by inflammation of hair follicles
  • Carbuncles are clusters of boils caused by bacteria
• Cold sores (fever blisters)


  • Caused by human herpesvirus 1
  • Blisters itch and sting
• Contact dermatitis


  • Caused by exposure to chemicals that provoke allergic responses
  • Itching, redness, and swelling of the skin
• Impetigo


  • Caused by bacterial infection
  • Pink, fluid-filled raised lesions around mouth/nose