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 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
- Meissner's corpuscles
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