Epidermis, Dermis, Hypodermis

What’s the main function of the integumentary system?

protection

Whats the superficial layer of the skin?

epidermis

The epidermis is___

avascular

What cells are the most abundant in the epidermis?

Keratinocytes

What protein do keratinocytes make? what is their product’s function?

They make keratin which makes the epidermis a tough protective layer

What other cells are in the epidermis?

Melanocytes, Langerhan cells, Merkel cells

What do melanocytes make? What is the function of their product?

They make melanin which is pigment, it protects the skin from UV damage

What are Langerhan cells? What is their function?

They are epidermis dentritic cells that alert and activate immune cells to a threat (bacterial/viral invasion)

What are merkel cells? What do they do?

They are sensory nerve endings that serve as touch receptors

What are the 5 layers of the epidermis? (from bottom to top)

Stratum basale, spinosum, granulosum, lucidum, corneum

What’s the acronym for the 5 layers?

Beautiful Skin Glows Like Crystals

What layer is the stratam basale/stratum germinativum? What does it do?

1st layer where stem cells grow into keratinocytes, melanocytes, and langerhan cells it is closest to the dermis

Where are nutrients most abundant in the 5 layers? (Top or Bottom)

Bottom

Which layer is the stratum spinosum? What does it do and what’s in it?

2nd layer (thickest)— many rows of dividing keratinocytes, melanin granules and langerhan’s cells are most abundant here

Which layer is the stratum granulosum? What happens here?

3rd layer— keratinocytes stop dividing, keratin and lamellar granules accumulate: Keratinization- cells harden and fill with keratin. Lamellar granules: contain water-resistant glycolipid

Which layer is the stratum lucidum? What happens here?

4th layer- only in thick skin— “clear layer” it is the flattened, dead, densley packed cells that don’t have organelles

Which layer is the stratum corneum? What happens here?

5th layer: 20-30 cells thick, dead cells completely filled with keratin for protection— layer is replaced by the division of deeper stratum basale cells— regenerates every 25-45 days

What does the dermis do/What is it?

It is a strong envelope that helps bind the body together— has areolar and dense irregular connective tissue that make up the papillary and reticular areas— thickness varies depending on where it is

What is the papillary layer a part of? What is it and what does it do?

Dermis; superficial dermal region— has capillary loops to bring nutirents to the epidermis, has nerve endings (meissner corpuscles) which are pain and touch receptions. Makes up the patterns of the finger prints and sweat pores

What is the reticular layer a part of? What does it do & whats in it?

Dermis; deepest skin layer, dense irregular connective tissue, blood vessels, sweat and oil glands, deep pressure receptors (lamellar corpuscles) phagocytes

What do collagen fibers do?

Effect toughness of skin— attract and bind to water

What do elastic fibers do/ pertain to?

Elasticity; aging decreases the amount of collagen and elastic fibers decrease, subcutaneous tissue looses fat

What isn’t a layer of the skin?

Hypodermis

What layer does temperature regulation pertain to? What happens?

Dermis(supplies with blood); Warm- capillaries get bigger and skin becomes reddened and warm —— Cold- blood passes the dermis capillaries so internal body temp can stay high

What is the hypodermis? What’s in it and what does it do?

subcutaneous layer, made up mostly of adipose tissue but also has areolar tissue, anchors skin to underlying tissues; shock absorber and insulator