3 main layers: _____________ Thin layer of _________ ___________ epithelium BI 201 Human Anatomy & Physiology What are the main layers of the Integ. System? ___________ Thicker, tough layer of _______ __________ connective tissue and other components Technically not part of the skin, varies in thickness depending in part on the amount of ___________ present __________

Most ___________ layer Comprised of stratified squamous epithelium Most cells are *_____________ (become filled with keratin) Some cells are: *___________ (give skin it’s pigmentation) *___________ (immune cells) BI 201 Human Anatomy & Physiology What are the epithelial details? Outermost layer sloughs off… takes ___ - ____ days to replace

BI 201 Human Anatomy & Physiology What are “mites and motes”? Most of the dust floating in sunbeams, covering the tops of bookshelves etc. is desquamated keratinocytes (i.e. _______ _____ ____) ______ ______ (Dermatophagoides) eat these cells. House dust allergies are generally Dust mite ______ _______________

5 layers (strata) _____ ________ __________ ________ Deepest layer, mitosis, pushes new cells upwards During “histo-prep” cells pull apart… still mitosis Keratohyalin granules, lamellar bodies release lipids The cell dies, organelles deteriorate leaving keratin Thick layer of keratinized (dead) cells that sloughs off BI 201 Human Anatomy & Physiology Is the epidermis homogenous deep to superficial?

Some drugs are administered by applying the drug to the skin (ex., a nicotine patch). The drug diffuses through the epidermis to the blood vessels in the dermis. What kind of substances can pass easily through the skin by diffusion? What kind have difficulty? BI 201 Human Anatomy & Physiology Take 5!!! Discuss with your neighbor and predict an answer.

Thick and Thin skin refers to ________ ______ not dermis or skin BI 201 Human Anatomy & Physiology Why are some people so “thick skinned”? Thick skin

_____ ___: Not all 5 layers present, but hair is! BI 201 Human Anatomy & Physiology Why are some people so “thick skinned”?

Contains all the “goodies” 2 layers _________ layer _________ layer Dermis is primarily what type of tissue? Consists of _________, _________ ____ and ___________ and _____ What types of fibers? _________ _________ _________ BI 201 Human Anatomy & Physiology What are the Dermis Details?

2 layers Reticular layer Papillary layer What is the function of the papillae? BI 201 Human Anatomy & Physiology What are the Dermis Details?

Epidermis of some skin follows contours of __________ _________ ______. BI 201 Human Anatomy & Physiology Is this in thin or thick skin? How, what, where and why do we have “fingerprints”?

___________ (cleavage) _____ The fibers in the dermis are not arranged ___________ at ________. Greater strength in “lines” due to orientation of ____________ ________. Surgeons make incisions parallel to tension lines when possible BI 201 Human Anatomy & Physiology Are all incisions created equally?

________ (stretch marks) As the skin is stretched the dermis “ruptures” and forms linear scars (____). Striae gravidarum & lineae albicantes Let’s predict the orientation of tension lines based on the direction of striae! BI 201 Human Anatomy & Physiology Is the skin equally strong in all directions?

BI 201 Human Anatomy & Physiology Is the skin equally strong in all directions?

_________, ______ ____ (____ of body fat) and macrophages Primarily ______ _________ tissue Also called _____________ or ___________ tissue BI 201 Human Anatomy & Physiology What are the Hypodermis Details?