Integument

Question 1

three major layers from outermost to innermost

Answer 1

• epidermis
• dermis
• hypodermis

Question 2

functions of the skin 6*

Answer 2

• 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

Question 3

thick skin

Answer 3

• located on palms and soles
• hairless
• fingerprint grooves
• SSKE

Question 4

thin skin

Answer 4

• located everywhere other than palms and soles
• usually has hair and hair associated glands
• SSKE

Question 5

epidermis layers

-exterior inward

Answer 5

• stratum corneum
• stratum lucidum
• stratum granulosum
• stratum spinosum
• stratum basale (germinativum)

Question 6

stratum basale

Answer 6

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

Question 7

hyperproliferation of the stratum basale

Answer 7

• HPV infection of basal keratinocytes gives rise to warts
• basal cell or squamous cells give rise to carcinoma
• melanocytes –> melanoma

Question 8

stratum spinosum

Answer 8

• prickle cell layer
• thickest living layer
• abundant desmosomes which give rise to the prickle appearance when sectioned

Question 9

stratum granulosum

Answer 9

• keratohyaline granules contain: filagrin, loricrin, and trichohyalin
• these granules are highly phosphorylated which allows them to stay heavily with hematoxylin

Question 10

stratum corneum

Answer 10

• dead cells packed with keratin
• the abundance of protein makes this layer eosinophilic
• lipids in this layer allow the skin to be water proof

Question 11

melanocytes

Answer 11

• 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

Question 12

melanin formation within melanosomes

Answer 12

• 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

Question 13

melanocyte activity is promoted by

Answer 13

• UV light

- melanocyte stimulating hormone

Question 14

melanin polymorphisms

Answer 14

• 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

Question 15

pigmentation variations

Answer 15

• 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

Question 16

tattoo

Answer 16

-need to get the ink in the dermis so scar tissue can form

Question 17

langerhans cells

Answer 17

• lantigen presenting
• no desmosomes, few IF
• derived from bone marrow

Question 18

merkel cell

Answer 18

-mechanoreceptors

Question 19

papillary

Answer 19

• this is where the ridges between the dermis and epidermis reside
• it increases the surface area for greater attachment

Question 20

hairs

Answer 20

• keratinized epithelial structures
• composed of a infundibulum, isthmus, bulb, and dermal papilla (epithelial-mesenchymal interaction)
• associated with sebaceous glands, apocrine glands, and arrector pili muscle
• melanocytes at the base of the hair follicle give the hair its color
• contains trichohyaline, which gives it its rigidity

Question 21

glands of the skin

Answer 21

• eccrine
• apocrine
• sebaceous

Question 22

eccrine gland of the skin

Answer 22

• simple, coiled tubular
• thermoregulatory
• salt balance
• has myoepithelial cells
• ducts modify the secretion

Question 23

sweat contains

Answer 23

• water
• urea
• NaCl
• dermcidin
• trace elements
• ions

Question 24

apocrine sweat glands

Answer 24

• simple, coiled tubular
• apocrine (or eccrine) secretion
• product is stored
• ducts do not modify the secretion
• restricted distribution
• develop at puberty
• activated by stress ad sexual stimulation
• glands contain myoepithelial cells

Question 25

sebaceous glands

Answer 25

- acinar morphology - holocrine secretion - secrete oily substance (sebum) - usually assocatied with hairs - may exist without hairs - fordyce spots on lip

Question 26

free nerve endings

Answer 26

- non encapsulated - thermoreceptors - mechanoreceptors - nociceptors - extend to stratum Gr.

Question 27

merkel endings

Answer 27

-non encapsulated | slow adapting mechanoreceptors

Question 28

meissners corpuscle

Answer 28

- encapsulated - rapidly adapting mechanoreceptors - high density = discriminatory (braille) - dermal papilla

Question 29

pacinian corpuscle

Answer 29

- encapsulated - rapidly adapting mechanoreceptor for vibration - up to 2 mm in length - located in hypodermis