Skin Histology

Strata of the skin from deep to superficial

basal, spinosum, granulosum, lucidum, corneum

skin with a prominent stratum corneum, distinct stratum lucidum, and robust stratum granulosum

thick skin

another name for thick skin

glabrous

location of thick skin

palms of hands and soles of feet

morphology of stratum corneum, granulosum, and lucidum in thin skin

less prominent, poorly developed, no obvious

which skin type contains hair follicles

thin

Epithelial classification of the epidermis

stratified squamous cornified epithelium

regenerative capacity of the epidermis

high

the epidermis rests upon projections of the ____, which form epidermal ridges (_____ on the fingertips)

dermis; fingerprints

Primary cell type in epidermis

keratinocytes

Keratinocytes originate in the _____ ______ layer and migrate upward, ________ as they progress superficially

basal epidermal; differentiating

the three morphologies of skin cells as they move upwards

columnar, cuboidal, squamous

what is the "waterproofing" protein?

keratin

Keratin has many _____ - containing amino acid residues. allowing for large numbers of _____ bonds across keratin proteins

sulphur; disulfide

keratinized cells have lost their ability to ______

proliferate

Cells become increasingly more ______ with more keratin

eosinophilic

morphology of cells in the stratum basale

single layer of cuboidal to columnar cells resting on the basal lamina

the most mitotically active of the epidermal layers

stratum basal

the stratum basal is attached to the basal lamina via _____ ______ and __________

anchoring fibrils; hemidesmosomes

what layer are melanocytes located in?

stratum basale

What layer contains stem cells

stratum basal

stratum basal keratinocytes are _____ due to large amounts of free ribosomes

basophilic

stratum basal keratinocytes contain large numbers of ___________, which are intermediate/keratin filaments

tonofilaments

The stratum spinosum is ________ ________ thick

several layers

another name for the stratum spinosum

spinous or prickle cell layer

how does morphology change as cells enter this layer

they become more flattened

in the stratum spinosum, the cytoplasm starts to become more ______ due to increased content of tonofilaments

eosinophilic

morphology of stratum spinosum cells

cuboidal to polygonal with a centrally located nucleus

in the upper layer of the s. spinosum, cells begin to synthesize ______ granules as well as ______ containing ____ _____ (aka membrane coating granules

keratohyalin; glycolipid; lamellar bodies

the thickness of the stratum granulosum _________

varies from one to a few cellular layers

The stratum _______ is the most superficial layer in which cells are nucleated

granulosum

cells in the s. granulosum contain abundant amounts of _____ and ______

keratohyalin; keratin

morphology of cells in the s. granulosum

flattened polygonal shape

what organelle are abundant in s. granulosum cells?

lamellar bodies

in the s. granulosum, a course ________ granular cytoplasm is apparent due to large amounts of keratohyalin granules

basophilic

keratohyalin granules are ______ in shape and size

irregular

Non-membrane bounded granules containing histidine- and cystine-rich proteins, which are the precursors of filaggrin

keratohyalin granules

_______ aggregates keratin filaments in the stratum cornuem

filaggrin

The S. ______ is found only in thick skin

lucidum

Morphology of cells in S. lucidum

nu nuclei or organelles

S. lucidum cells are rich in _____, a substance thought to be a metabolite of keratohyalin

eleidin

cells in the s. lucidum are weakly _______

eosinophilic

morphology of s. lucidum

extremely flat, no nucleus

cytoplasm of the s. lucidum contains large amounts of _____ filaments embedded in an electron-dense matrix

eleidin

the s. _______ is the most superficial layer in thick skin

cornuem

morphology and layering of s. corneum; keratin amount

15-20 layers of non-nucleated flat cells with copious keratin

the outermost structures of the s. corneum are called _______, which are continuously shed by the process of _________

squames; desquamation

how long does keratinization take int he s. corneum

2-6 hours

melanin is stored in ______

melanosomes

melanosomes contain _______, a UV-sensitive enzyme involved in melanin synthesis

tyrosinase

melanocytes are attached to the basal lamina via __________

hemidesmosomes

melanocytes are _______ in origin

neural crest

Melanosomes move from melanocytes to keratinocytes by _________

cytosecretion

exocytosis of the membrane-bound structure by one cell and endocytosis of that structure by another cell

cytosecretion

melanin aggregates on the ______ side of the nucleus

superficial

two forms of melanin

eumelanin and phenomelanin

brownish-black melanin pigment

eumelanin

reddish-yellow melanin pigmant

pheomelanin

_______ has the highest concentration of melanin

hair

Are langerhans cells keratinocytes?

no

Langerhan's cells are located primarily in the S. ______, originate in the ___ ____, are also known as ______ cells, and ____ _____adhere to other cells. They play a role in ______ response, specifically in delayed __________ reactions.

spinosum; bone marrow; dendritic; do not; immune; hypersensitivity

Are Merkel's cells keratinocytes?

no

Merkel's cells play a role in ___ and local ____ control. They are located in the s. _______, near well ______ and _____ connective tissue. They possess _____ and ______, which is suggestive of an ______ origin.

perception; endocrine; basale; vascularized; innervated; desmosomes; tonofilaments; epithelial

The Merkel's corpuscle consists of the Merkel cell and the _____ contacting it

neuron

The dermis is _____- in origin

mesodermal

Dermis is composed of irregular connective tissue containing type ____ and _____ collagen and networks of _____ fibers

I; III; elastic

The the dermis is structurally organized into a superficial ______ layer; and a deeper more extensive _____ layer

papillary; reticular

The papillary dermis forms the ____ ____. It contains type _____ and _____ collagen. It contains ____ ____ that nourish but do not enter the epidermis and sensory receptors called _____ ______

dermal papillae; I/III ; capillary loops; Meissner's corpuscles

Meissner's corpuscles consist of 1 or 2 _____ endings of myelinated fibers, which follow spiral paths within the corpuscle

unmyelinated

The sustentacular component of Meissner's corpuscles consists of ____ _____ ____

flattened Schwann cells

Meissner's corpuscles convey _____ frequency, ______ stimuli

low; vibratory

Pacinian corpuscles are found in the _______ and deeper areas of the ______ dermis

hypodermis; reticular

Pacinian corpuscles respond to _____ and ______ through displacement of the _____ _____, which results in depolarization of the axon

pressure; vibration; capsule lamellae

Ruffinis corpuscles are the simplest ________ ______ and are abundant in what two body parts? The function in _____ and ______ reception

encapsulated mechanoreceptors; digits and breasts; pressure; touch

Sweat glands can be either _____ or ______ in nature

eccrine; apocrine

Apocrine sweat glands are associated with ____ _____

hair follicles

Eccrine sweat glands are not associated with _____ ______, and are found all over except the ___ and ____ _____

hair follicles; lips; external genitalia

Eccrine sweat glands are ______, simple tubular glands consisting of a ______ unit and _____

coiled; secretory; duct

Eccrine swear glands are formed from down growths of ________

epithellium

Sweat gland type innervated by cholinergic fibers? What does this mean?

eccrine; they are involved in thermoregulatory sweating

three cell types of eccrine sweat glands

dark, clear, myoepithelial cells

eccrine sweat gland cell type that lines the lumen of the gland, contains secretory granules, and form intercellular canaliculi

dark cells

Eccrine sweat gland cell type that underlie the dark cells and are rich in mitochondria and glycogen

clear cells

Eccrine cell type that contract to aid in the expression of the gland's secretions into the duct

myoepithelial cells

An ______ component of gland - modifies the secretory product by absorbing and/or excreting electrolytes, urea, lactic acid, drugs, etc.

active

Apocrine sweat glands are responsive to ______ influences

hormonal

The secretory process of apocrine glands is actually ______

merocrine

apocrine sweat glands are innervated by what system?

sympathetic

Sebaceous glands are _____ glands, meaning ___________

holocrine; they release their entire cytoplasm upon secretion

Sebaceous glands are branched ______ glands with a short _____ portion

acinar; ductal

Put the following in the correct order:

1) eventually their nuclei shrink and cells

disintegrate, releasing their secretory product

into the pilosebaceous canal

2) secretory sacs (acini) divide, giving rise to

daughter cells

3) as these cells mature, they synthesize lipid-

rich secretory product, which accumulates in

their cytoplasm

2, 3, 1

three segments of the hair follicle

infundibulum, isthmus, inferior segment

the pilosebaceous apparatus consists of the ______ and its ______

hair follicle; associated sweat glands

Layers of hair from deep to superficial

medulla, cortex, cuticle

technical name for the root of a hair

connective tissue papilla

Which layer of the hair is present only in thick hair?

medulla

in the hair, cuboidal cells are located in the ____ layer, while squamous cells are present in the ____ LAYER

cortex; cuticle

The nail bed is continuous with the S. _____ and S> _____

basale; spinosum

The cuticle is continuous with the S. _____

corneum

Reticular dermis is primarily composed of Type ______ collagen fibers oriented into regular lines of tension called _____ _____

I; Langer's lines