Chapter 5-1 & 5-2Integumentary system

Integumentary System

• 2 major components:• ________________________ membrane

• Epidermis• Dermis

• Accessory structures• Hair• _______________• Multicellular ______________________ glands

Functions of Skin and Hypodermis

• Protection- underlying tissues and organs• ____________________- salts, H2O, and organic wastes by glands• Maintenance- normal body temp• Production- melanin and _________________• Synthesis of Vitamin D3• __________________- lipids in adipocytes• Detection- touch, pressure, pain and temp

Epidermis

• Stratified squamous epithelium• ____________________• Rely on diffusion of nutrients and O2 from capillaries within dermis• Dominated by keratinocytes- from several layers• Contain large amounts of keratin

• Thin skin- most of body surface (4 layers)• ____________- palms of hands and soles of feet ( 5 layers)

Layers of Epidermis

• Stratum germinativum• Stratum spinosum• Stratum granulosum• Stratus lucidum• Straus corneum

Stratus Germinativum

• Innermost epidermal layer• __________________________ attach cells of this layer to basal

lamina• Forms epidermal _________________- extend into dermis and are

adjacent to dermal papillae• Ridges on palms and soles increase surface area and increase friction• Genetic and doesn’t change

• __________________ cells- main cells and replace lost superficial keratinocytes at surface

Stratum Spinosum

• Each time a stem cell divides, one of the daughter cells is pushed here• 8-10 layers of keratinocytes bound by _____________________• Contains Langerhans (___________________) cells- participate in

immune response

Stratum Granulosum

• 3-5 layers of keratinocytes derived from stratum spinosum• Most cells have stopped dividing at this layer and started making large

amounts of keratin and keratohyalin

• ___________________- tough fibrous protein; basic component of hair and nails

Stratum Lucidium

• Thick skin of palms and soles• Cells filled with ________________

Stratum Corneum

• Exposed surface• 15-30 layers of keratinized cells• ___________________________- formation of protective, superficial

layers of cells filled w/ keratin; all exposed surfaces except anterior of eyes• Takes 15-30 days for a cell to move from stratum germinativum to

stratum corneum

Stratum Corneum

• Water resistant but not waterproof• Water from interstitial fluids slowly penetrates surface • ____________________________________-unable to see or feel

water loss; approx. 500 ml a day• Sensible perspiration- produced by active ______________ glands

5-2Skin Color

Epidermal Pigmentation

• __________________- orange- yellow pigment• Most apparent in cells of stratum corneum of light-skinned indiv.• Also accumulates in fatty tissues in deep dermis and SQ layer• Found in orange vegetables• Can be converted to vitamin A

Epidermal Pigmentation

• ___________________- brown, yellow-brown, or black pigment• Produced by ________________________- stratum germinativum

• Differences in skin pigmentation among indiv. do not reflect different # of melanocytes• Represents different levels of synthetic activities

• Ex: albino indiv. Are distributed normally but cells are incapable of producing melanin

Freckles

• Small pigmented areas on skin• Areas where _________________________ that produce larger

amounts of melanocytes

Lentigos

• Similar to freckles• Regular borders• Contain abnormal ___________________________• Senile lentigos- ___________________________

Ultraviolet Radiation

• Small amount is beneficial• Can damage DNA, cause mutations and promote development of

cancer• Over time, cumulative damage can harm ______________________

causing impaired maintenance of dermis- premature _____________________

Role of Dermal Circulation

• When bound to oxygen, hemoglobin is bright red, giving capillaries in the dermis a reddish tint• When blood supply is temporarily reduced, skin becomes pale• _____________________- bluish discoloration; O2 levels decline in

tissues

___________________________

• Liver can’t excrete bile• Yellowish pigment accumulates in body fluids• Advances stages- whites of eyes and skin turn yellow

__________________

• Individuals lose melanocytes• Incidence increases among individuals with thyroid gland disorders