integumentary system

what is the purpose of vertebrate integument

• protect from abrasion

• protect against water loss

• barrier to disease causing pathogens

• protection from UV light

• temperature regulation

• contains sensory receptors (touch)

• excretion (limited) evaporation cooling

what are the layers of the skin

epidermis and dermis

langerhans

defensive cells (help with immunity)

melanocytes

• produce pigment melanin

• skin coloration

• protection from UV light

merkle cells

touch receptors

karatinocytes

• primary cell types

• produce insoluble protein (keratin) \

• amount of keratin increases from inside to outside

• keratin fills cytoplasm and impairs nutrient diffusion.. cell dies

dermis layer

• inner layer of skin, thicker than the epidermis

• highly vascularized

• contains sensory structures, nerves, and glands

• origin of hair, feathers and scales of vertebrates

sensory structures

• temperature regulation

• produce sweat (primarily water)

• 2.5 million in body

• releases heat

sebaceous glands

• all over body except for palms and soles

• large on face, neck and upper chest

• produce sebum- lubricates and softens hair and skin

hypodermis

• lies beneath dermis; not a layer of skin

• contains much adipose (fat) tissue

• function: body contour and insulation

• females have thicker layer or adipose tissue than males (softer)