L23 - integument

Question 1

what body parts does integument include?

Answer 1

skin, sweat glands, sebaceous glands, hair, nails

Question 2

functions of skin

Answer 2

protect
regulate temperature - sweat
receive sensory input
absorb UV light to make vitamin D
excrete waste - sweat

Question 3

dermis and epidermis tissue type

Answer 3

dermis is loose CT

epidermis is stratified squamous keratinized epithelium

Question 4

thin skin vs. thick skin

Answer 4

THIN skin - found on most body surfaces
-can be hairy, oily, sweaty, etc.
- has hair follicles, arrector pilli m., sebaceous and sweat glands
- basale, spinosum, thin corneum
THICK skin - soles and palms, form fingerprints
- sweaty, subject to abrasion
- NO hair follicles/arrector pilli/sebaceous
- HAS sweat glands
- basale, spinosum, granulosum, lucidum, corneum
- prominent epidermal ridges, dermal papillae, true dermal ridges

Question 5

epidermis function characteristics

Answer 5

• come from ectoderm
• stratified squamous keratinized epithelium
• epidermal ridges interdigitate with dermal papilla (aka rete ridges)
• avascular (nutrients come from dermis)
• sensory nerve endings
• cells are keratinocytes and non-keratinocytes

Question 6

keratinocytes

Answer 6

• epithelial cells
• mitotically active (night) in stratum basale to renew skin
• cells migrate toward skin surface while accumulating keratin filaments
• desquamate 120-30 days

Question 7

non-keratinocytes include…?

Answer 7

langerhans, merkel cells and melanocytes

Question 8

Langerhans cell

Answer 8

function = defense
dendritic, antigen-presenting cells (present antigen to lymph node)
formed from bone marrow precursors that enter the bloodstream and epidermis and differentiate into Langerhans
mainly found in stratum spinosum and superficial dermis
pale cytoplasm, long cytoplasmic processes
have membrane-bound Birbeck (vermiform) granules which function in protection from antigens

Question 9

Merkel cell

Answer 9

mechanoreceptors - fine, detailed tactile info (texture and shape)
in hair follicle base and fingertips, attached to keratinocytes by desmosomes
Merkel disk - dilated part of peripheral nerve process that senses and relays sensory info
Merkel cell neurite complex = Merkel cell + Merkel disc - unmyelinated, found in stratum basale

Question 10

melanocytes

Answer 10

protect DNA - natural sunscreen
arise from neural crest cells
found in stratum basale and superficial dermis
cytoplasmic processes extend into stratum spinosum
make melanin for keratinocytes
make tyrosinase and send to melanosomes
same # melanocytes in all races, but pigmentation is determined by tyrosinase activity, # granules, size of granules, breakdown rate of melanin, and distribution

Question 11

explain the process of tyrosinase production and conversion

Answer 11

tyrosinase is produced by rER in melanocytes
UV light activates tyrosinase
tyrosine is pumped into melanosomes by GA and is converted to melanin
melanin passes into cytoplasmic processes of melanocytes and is released via vesicles to nearby cells

Question 12

vitiligo

Answer 12

autoantibodies attack melanocytes leading to unpigmented skin patches

Question 13

albinism

Answer 13

tyrosinase defect/absence so no melanin is made

melanocytes are present

Question 14

malignant melanoma risk factors and ABCDE diagnosis

Answer 14

risk factors: heredity, light skin, excess sunlight
A appearance (according to Patestas) - malignant cell nodules
B border
C color
D diameter - bigger than pencil eraser
E evolving

Question 15

icthyosis

Answer 15

excessive keratin buildup (hyperkeratosis) leading to fishlike scales because no keratin is sloughed off

Question 16

thick skin layers from innermost to outermost

Answer 16

basale (germinativum)
spinosum
granulosum
lucidum
corneum

Question 17

thin skin layers from inner to outermost

Answer 17

basale
spinosum
thin corneum
*no lucidum or granulosum - deep layers have desmosomes

Question 18

how does the basement membrane attach to epidermis to dermis

Answer 18

glues - carbs

anchors - collagen fibers

Question 19

name 2 layers of dermis

Answer 19

papillary layer and reticular layer

Question 20

stratum basale: function and description

Answer 20

innermost layer of thick skin, rests on BM
functions = cell renewal most intense mitotic activity occurs here
also anchors epidermis to basement membrane via hemidesmosomes and to neighboring cells via desmosomes
melanocytes found here

Question 21

basal cell carcinoma

Answer 21

chronic sun exposure

subepidermal blood vessels present in a “pearly papule” on skin

Question 22

stratum spinosum: function and description

Answer 22

function = binding, protection
thickest layer of thick skin epidermis
found between basale and granulosum
keratinocytes have intercellular “bridges” (interdigitating processes) connected by desmosomes, causing prickly appearance
contains tonofilaments (intermediate filaments - type of cytokeratin) in cell periphery and in “bridges”
contains Langerhans cells
note mitosis in basal layer

Question 23

stratum granulosum: function and description

Answer 23

function = waterproofing
3-4 layers of diamond shaped cells with nuclei containing fragmented DNA
has many granules in the cytoplasm

Question 24

describe 2 types of granules in stratum granulosum

Answer 24

keratohyalin granules - contain soft keratin (protein)
membrane-coating granules aka lamellar bodies - contain lipid which is excreted to ECS to waterproof
- this also stops nutrient passage to superficial cells (lucidum and corneum) die

Question 25

stratum lucidum, function and description

Answer 25

``` function = protection subdivision of stratum corneum light staining no organelles, nonviable cells contains keratin filaments really only perceptible in thick skin ```

Question 26

stratum corneum, function and description

Answer 26

thick layer of flattened, keratinized, dessicated, dead cells - no nuclei/organelles friction results in thickening of this layer resulting in a callus no desmosomes between superficial cells so easily desquamate near surface deeper cells have desmosomes

Question 27

dermis function and characteristics

Answer 27

- CT layer of skin - arises from mesoderm - function = strength (collagen), defense, nutrition/thermoregulation (capillary loops), sensation and stretch - Meissner corpuscles (mechanoreceptors, fine touch) and Krause end bulbs

Question 28

dermal papillae, dermal ridges and epidermal ridges

Answer 28

- dermal papillae are scallops in the dermis and epidermal ridges fill in between those mounds - dermal ridges are parallel to and in between dermal papilla and these form fingerprints

Question 29

describe the papillary layer of dermis

Answer 29

- superficial, thin layer of loose CT - forms dermal papillae - function = defense against invaders - has collagen III (reticular) + elastic fibers + collagen VII (anchor) - has fibroblasts, macrophages, plasma cells, mast cells - has melanocytes

Question 30

describe the reticular layer of dermis

Answer 30

- dense irregular collagenous CT (tensile strength) and thick elastic fibers (stretch) - has collagen I fibers in bundles that are oriented in regular lines of tension (Langer's lines) - has fibroblasts, mast cells, lymphocytes, macrophages, fat cells - has hair follicles, arrector pili muscles, sebaceous glands, and sweat glands - has Pacinian corpuscles (pressure/vibrations) and Ruffini corpuscles (tensile forces) - proteoglycans - dermatan sulfate

Question 31

where can surgical incisions be made to minimize scarring?

Answer 31

oriented parallel to Langer's lines

Question 32

``` describe the functions and location of each: Pacinian corpuscle Ruffini corpuscle Meissner corpuscle Krause end bulb Langerhans cell Merkel cell ```

Answer 32

Pacinian corpuscle - pressure/vibe Ruffini corpuscle - tensile forces both in reticular layer of dermis Meissner corpuscle - mechanoreception Krause - unknown fxn both in papillary layer of dermis Langerhans cell - defense/antigen-presenting, in stratum spinosum Merkel cell - mechanocreception, in stratum basale - fingertips for tactile both in epidermis

Question 33

which skin layers are injured in superficial (first degree), partial thickness (second degree) and full thickness (third degree) burns?

Answer 33

superficial burns = epidermis partial thickness = papillary AND reticular layer of dermis full thickness = hypodermis - not part of skin (bc its fascia) - and maybe underlying muscle (4th degree)

Question 34

hypodermis characteristics

Answer 34

- NOT skin - superficial fascia - loose CT deep to dermis - has adipose tissue - varies in thickness - injured in full thickness burns

Question 35

name 3 types of glands in the skin?

Answer 35

eccrine sweat, apocrine sweat, and sebaceous

Question 36

describe eccrine sweat glands

Answer 36

- function = thermoregulation - simple coiled tubular glands - also in dermis or hypodermis of entire body - duct opens to epidermis - has myoepithelial cells - secretory segment = simple cuboidal to low columnar (or pseudostratified) - duct segment = stratified cuboidal epithelium

Question 37

innervation of eccrine and apocrine sweat glands?

Answer 37

postganglionic sympathetic fibers | - eccrine have cholinergic endings and piggy-back on arterial vessel walls

Question 38

describe myoepithelial cells

Answer 38

- surround the secretory unit of both sweat glands and are covered by the basal lamina of eccrine sweat glands - contain actin and myosin filaments for contraction which squeeze out the secretions

Question 39

describe apocrine sweat glands

Answer 39

- found in axilla, areola and anal region (AAAA's) - modified apocrine glands include ceruminous glands of external auditory meatus and glands of Moll in eyelids - larger than eccrine - also found in deep dermis and hypodermis - duct opens to hair follicle, superficial to sebaceous gland duct - influenced by hormones @ puberty - secretion is viscous and odorless when released onto skin until metabolized by bacteria

Question 40

describe secretory and duct units of apocrine and eccrine sweat glands

Answer 40

- both secretory units are simple cuboidal to low columnar - eccrine duct = stratified cuboidal - apocrine lumen is larger than eccrine - both use merocrine method

Question 41

describe sebaceous glands

Answer 41

- dermis and hypodermis, throughout body, more # in scalp and face - secrete sebum = cholesterol, triglycerides and dead cells - are appendages of hair follicles - influenced by hormones @ puberty - acinus made of small basal cells (immature, periphery) and large round cells (mature, degenerating) - duct made of strat squamous - holocrine secretion

Question 42

difference between sweat and sebaceous glands?

Answer 42

``` sweat = merocrine vs. sebaceous = holocrine sweat = columar vs. seb = strat squamous ```

Question 43

describe 3 types of hair

Answer 43

``` vellus = short, soft, fine, pale, eyelids terminal = long, hard, coarse, dark, scalp and eyebrows lanugo = fetus ```

Question 44

describe a hair follicle | hair bulb & shaft (3 layers)

Answer 44

hair bulb: - hair root = matrix and dermal papilla - internal root sheath = Henle's layer (outer) + Huxley's layer (middle) + cuticle (inner) - external root sheath hair shaft = medulla* (inner) + cortex (middle) + cuticle (outer) *medulla present in thick hair

Question 45

arrector pili muscles

Answer 45

``` smooth muscle attached to hair follicle @ midpt obliquely contraction raises hair "cradle" seb glands sympathetic innervation ```

Question 46

nails - describe parts and functions

Answer 46

nail plate + nail bed + nail root/matrix ``` plate = hard keratin bed = strat. basale and spinosum matrix = nail growth - forms keratin for plate eponychium hyponychium lunula = white crescent ```

Question 47

describe eponychium and hyponychium

Answer 47

- eponychium = nail cuticle, proximal fold, made of stratum corneum - hyponychium = thickened epithelium under nail plate