ANAT 7390 Lecture Notes - Lecture 1: Thermoreceptor, Stratum Corneum, Epithelial Root Sheath
4 Jun 2018
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1!
TOPIC&IX:&INTEGUMENTARY&SYSTEM!
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A) Integumentary&System:&Overview&
! consists!of:!
o skin!
o hair,!nails,!glands!
o sense!receptors!(nervous)!
o muscles!
!
B) Skin&-&Layers&
! 2!layers!
1) Epidermis!–!upper!layer!
2) Dermis!–!lower!layer!
! below!skin!=!hypodermis!
! characteristics!of!each!layer:!!
1) Epidermis!!
! stratified!squamous!epithelium!(from!ectoderm)!
! avascular!
! separated!into!4-5!strata!(sub-layers)!based!on!cell!types:!
o Stratum!Basale!!
! single!row!of!cells!
! 2!cell!types:!
i. keratinocytes!(90%)!
! undergo!mitosis!
! make!keratin!(tough!protein)!
! migrate!to!surface!as!new!cells!produced!in!basale!
ii. melanocytes!(10%)!
! produce!pigment!(melanin)!for!UV!light!protection!
o e.g.!sunburns,!wrinkles!(collagen!damage),!
cancer!(DNA!damage).!!
! skin!colour!:!!
o we!all!have!the!same!relative!number!of!
melanocytes,!but!cells!produce!different!
amounts/shades!of!melanin!
o albinos!=!no!melanin!
o blood!(hemoglobin)!-!in!dermis!can!give!a!
pinkish!tinge!to!fair!skinned!people!
o Stratum!Spinosum!!
! limited!cell!division!
o Stratum!Granulosum!!
! contains!dark!staining!granules!
o Stratum!Lucidum!!
! flat,!dead!cells!(too!far!from!blood!supply)!
! visible!ONLY!in!thick!skin!
Document Summary
Topic ix: integumentary system: integumentary system: overview. Consists of: skin, hair, nails, glands, sense receptors (nervous, muscles, skin - layers. 2 layers: epidermis upper layer, dermis lower layer. Separated into 4-5 strata (sub-layers) based on cell types: stratum basale. Migrate to surface as new cells produced in basale: melanocytes (10%) Produce pigment (melanin) for uv light protection: e. g. sunburns, wrinkles (collagen damage), cancer (dna damage). Contains dark staining granules: stratum lucidum flat, dead cells (too far from blood supply) 20 - 30 layers of flat dead cells filled with keratin (tough protein), surrounded by waterproofing glycolipid (prevents water loss) Shed and replaced from below: dermis. Contains blood vessels, nerves, glands, hair follicles. 2 sub-layers (ct from mesoderm): papillary layer (beneath epidermis) Has projection into epidermis = dermal papillae in thick skin these form dermal ridges = fingerprints (improve grip: reticular layer. Dense irregular ct: hypodermis (not part of skin)
