lect 26 & 27 (T3): integument

Question 1

what does the dermis of the skin correspond to

Answer 1

lamina propria of a mucous membrane

Question 2

what are characteristics of the primary dermal ridge

Answer 2

related to finger prints
found everywhere except forehead, external ear, perineum, and scrotum
formed during 3rd to 4th months of fetal life
subdivided into 2 secondary dermal ridges by inter papillary peg

Question 3

what is the inter papillary peg

Answer 3

downward growth of epidermis along crest

Question 4

what are characteristics of the secondary dermal ridge

Answer 4

occur in double rows, branched

thin, collagenous, reticular and elastic fibers

Question 5

what is the dermal papillae

Answer 5

upward projections from each secondary dermal ridge

Question 6

what are characteristics of thick skin

Answer 6

occurs only on palms and soles and is hairless

displays all 5 epidermal layers

Question 7

what are characteristics of thin skin

Answer 7

occurs over rest of body
thinnest in eyelids
thickest on back
thicker on extensor surfaces than flexor
epidermal layers less distinct and lacking stratum lucidum

Question 8

what are the layers of the epidermis

Answer 8

stratum basale (deepest)
stratum spinosum
stratum granulosum (represented by only a few cells in thin skin)
stratum lucidum (absent in thin skin)
stratum corenum (most superficial)

Question 9

what types of cells are in the stratum basale

Answer 9

single layer cells held together by desmosomes (hemidesmosomes hold layer to basal lamina)

Question 10

what does mitotic activity in the stratum basal produce

Answer 10

stem cells differentiating keratinocytes

Question 11

what type of cells are in the stratum spinosum

Answer 11

polyhedral shaped cells (prickle cells)

Question 12

what keratins are in stratum spinosum

Answer 12

keratins 1 and 10 (high molecule weight)

Question 13

what keratins are in stratum basale

Answer 13

keratins 5 and 14 (low molecular weight0

Question 14

what do the lamellar bodies in stratum spinosum contain

Answer 14

lipid, carbs, and hydrolytic enzymes

Question 15

what do tonofibrils do

Answer 15

form intercellular bridges

Question 16

what are characteristics of stratum granulosum

Answer 16

multilayerd
keratins 2e and 9
flattened nucleated keratinocytes
keratohylain aggregates
membrane-coating granules (lamellar bodies) 
tonofilaments

Question 17

keratokyalin aggregates do what

Answer 17

filagrin induces cross-linkage of keratin filaments by disulfide bonds
no limiting membrane

Question 18

what are characteristic lucidum

Answer 18

flat keratinocytes lacking nuclei and organelles
only found in thick skin
contains eleiden

Question 19

what are characteristics of stratum corneum

Answer 19

multilayered
thicker in thick skin
enucleated, flattened, dead keratinocytes
cytoplasm replaced by keratin
cytoplasm contains: keratin cross-linked with filaggrin (cornified cell envelope)

Question 20

what are the layers of the cornfield cell envelope

Answer 20

extracellular: muti-lamellar lipid layer covalently linked to involucrine
intracellular: involucrine, small proline-rich proteins, loricrin, fillagrin and keratin complex

Question 21

what do tight junctions in the stratum granulosum contain

Answer 21

claudin-1 and claudin-4 (components of the permeability barrier)

Question 22

what are dermis characteristics

Answer 22

dense fibrous irregular CT layer beneath epidermis
derived from embryonic mesoderm
induces development of epidermis and epidermal derivatives
supports epidermis

Question 23

hypodermis characteristics

Answer 23

loose CT that underlies dermis
corresponds to superficial fascia of gross anatomy
technically not part of skin
may contain fat cells that can form a thick layer called the panniculus adiposus

Question 24

what are the 2 layers of the dermi

Answer 24

papillary and reticular layer

Question 25

why are characteristics of papillary layer of ddermis

Answer 25

loose CT separated from epidermis by basal lamina network of fine elastic fibers and abundant capillaries

Question 26

what are characteristics of reticular layer of dermis

Answer 26

dense irregular CT | includes fibrocytes, macrophages, and adipocytes

Question 27

where do langerhans cells come from

Answer 27

monocytes

Question 28

where do langerhans cells migrate from and to

Answer 28

migrate from epidermis to lymph nodes

Question 29

where are merkel cells usually located

Answer 29

stratum germinativum

Question 30

what does the periderm slough off to form

Answer 30

vernix caseosa

Question 31

what does the inner cuboidal germinal layer of the epidermis proliferate to form

Answer 31

adult layers of the epidermis and derivatives

Question 32

what is the dermis derived from

Answer 32

mesoderm

Question 33

what are characteristics of sebaceous glands

Answer 33

holocrine glands branched acinar glands with short ducts found everywhere except palms and soles continuously produce sebum (release into hair follicle) growth is stimulated at puberty by sex hormones

Question 34

what are characteristics of sweat (sudoriferous glands)

Answer 34

both merocrine and apocrine glands

Question 35

what are characteristics of merocrine glands

Answer 35

coiled, simple tubular secretory portions lined by simple epithelium apical dark secretory cells secrete glycoproteins basal clear cells secrete water and electrolytes myoepithelial cells duct system cholinergic endings

Question 36

what does the duct system of merocrine glands consist of

Answer 36

stratified cuboidal epithelium except in epidermis

Question 37

where are apocrine glands found

Answer 37

labia majora, areola, and axillary and anal regions

Question 38

where do the excretory duct open into for apocrine glands

Answer 38

hair follicle

Question 39

when do apocrine glands become active

Answer 39

puberty

Question 40

what are the special types of sweat (sudoriferous) glands

Answer 40

ceruminous glands | glands of moll

Question 41

how do apical dark cells secrete glycoproteins

Answer 41

by exocytosis (merocrine secretion)

Question 42

what are the components of a hair follicle

Answer 42

root, free shaft, hair follicle

Question 43

what are characteristics of a hair bulb

Answer 43

expanded lower part of hair follicle matrix vascularized dermal papilla

Question 44

what is the external root sheath of hair follicle

Answer 44

down growth of epidermis

Question 45

what is the internal root sheath of the hair follicle generated by

Answer 45

bulb matrix

Question 46

what are the layers of the internal root sheath of hair follicle

Answer 46

Henle's layer huxley's layer cuticle (interlocks with cuticle of hair shaft)

Question 47

what are the layers of the hair shaft

Answer 47

medula (innermost) cortex cuticle

Question 48

where do the edges of the cuticle of the hair shaft tend to point

Answer 48

downward