Integumentary System

Apparently there is no chapter/section for this in the book?

Integument

• the skin and all accessory structure (hair, feathers, scales)

Skin

• The largest vertebrate organ
• major part of the integument system

Vertebrate integument and derivatives

Functions

• Protection form abrasion
• protects against water loss
• barrier to disease causing pathogens
• protection from UV light
• temperature regulation
• contains sensory receptors
• excretion (limited)

Vertebrate Integument

• skin and all other accessories
• skin is the largest organ o vertebrates
• skin consists of 2 layers
  • epidermis
  • dermis

Epidermis

• outer layer
• nutrients diffuse into the epidermis form the dermis
• stratified squamous epithelial cells

Cell types

• langerhans cells
  • defensive cells
• Melanocytes
  • produce pigment melanin
  • skin coloration
  • protect form UV light
• Merkel cells
  • touch receptors
• Keratinocytes
  • primary cell type
  • produce insoluble protein Keratin
  • amount of keratin increases from the inside to outside
  • keratin fill cytoplasm and impairs nutrient diffusion, cell dies

Dermis

• Inner layer of skin
  • thinner than dermis
• highly vascularized
• contains:
  • sensory structures
  • vessels
  • nerves
  • glands
• Origin of hair/scales/feathers in vertebrates
• Sensory structures
  • Meissner's corpuscles
    • light touch
  • Pacinian corpuscles
    • deep vibrations

Sweat Glands

• temperature regulation
• produce sweat (primarily water)
  • evaporating cooling
  • release of waste ions
• 2.5 million on the body
• release of heat

Sebaceous Glands

• all over body, except palms and soles
• large on face, neck, and upper chest
• produce sebum
  • lubricates and soften hair and skin
  • water proofing in aquatic mammals

Hypodermis

• subcutaneous layer
  • below the dermis
• not a layer of the skin
• contains much adipose (fat) tissue
• females have thicker layer of adipose tissue than males

Function

• body contour
• insulation
• support the skin