Integument Flashcards
1
Q
three major layers from outermost to innermost
A
- epidermis
- dermis
- hypodermis
2
Q
functions of the skin 6*
A
- protective: keratin synthesis, hairs, sebum
- sensory: specialized nerve endings
- thermoregulation: sweat glands control of blood flow
- metabolic: vitamin D synthesis, ion balance
- immunological: langerhans cells and wandering lymphocytes
- absorption* : nicotine, steroids
3
Q
thick skin
A
- located on palms and soles
- hairless
- fingerprint grooves
- SSKE
4
Q
thin skin
A
- located everywhere other than palms and soles
- usually has hair and hair associated glands
- SSKE
5
Q
epidermis layers
-exterior inward
A
- stratum corneum
- stratum lucidum
- stratum granulosum
- stratum spinosum
- stratum basale (germinativum)
6
Q
stratum basale
A
turnover takes 15-30 days
- stem cells are located at the top of ridges and the have a vertical mitotic axis, moving the new cells down into the bottom of the ridge
- once at the bottom of the ridge the cells divide along a horizontal mitotic axis
- contain melanocytes and merkel cells
7
Q
hyperproliferation of the stratum basale
A
- HPV infection of basal keratinocytes gives rise to warts
- basal cell or squamous cells give rise to carcinoma
- melanocytes –> melanoma
8
Q
stratum spinosum
A
- prickle cell layer
- thickest living layer
- abundant desmosomes which give rise to the prickle appearance when sectioned
9
Q
stratum granulosum
A
- keratohyaline granules contain: filagrin, loricrin, and trichohyalin
- these granules are highly phosphorylated which allows them to stay heavily with hematoxylin
10
Q
stratum corneum
A
- dead cells packed with keratin
- the abundance of protein makes this layer eosinophilic
- lipids in this layer allow the skin to be water proof
11
Q
melanocytes
A
- neural crest derivatives
- lie superficial to BL
- constant numbers between races
- synthesize tyrosinase (unique to this cell type)
- pigment donation to the surrounding cells so they can use it to protect against UV
- melanosomes contain the melanin
12
Q
melanin formation within melanosomes
A
- tyrosine converted to DOPA which is convertedto melanin
- this breaks off from the golgi
- these melanosomes are taken up by the cells surrounding the melanocyte and is used as a melanin cap which is placed between the sun and the nucleus
13
Q
melanocyte activity is promoted by
A
- UV light
- melanocyte stimulating hormone
14
Q
melanin polymorphisms
A
- eumelanin: this is the wild type form of melanin found in most people
- phaeomelanin: this is a mutant form which does not block UV light as well, causes red hair, higher risk for melanoma, weaker antioxidant but does allow the individual to make much more vitamin D
15
Q
pigmentation variations
A
- freckles: ephelides, localized increase in melanin production, develop in response to sun exposure
- moles: nevus, localizzed aggregation of melanocytes, appear soon after birth
- albinism: lack of pigment, tyrosinase defect type 1
