integ sys. (pg. 3 and 4)

stratum basale, stratum granulosum, stratum spinosum, stratum lucidum, stratum corneum

what are the layers of the epidermis?

stratum germinativum, basal layer

what is the other term for stratum basale?

stratum granulosum

Single layer of cells supported by a basal lamina amnd it is the innermost layer of the epidermis

stratum basale

Cells are cuboidal or low columnar, nucleus is large and cytoplasm is basophilic

stratum basale

Intermediate keratin filaments

stratum basale

Contain stem cells, its proliferation is responsible for the continuous renewal of the epithelium

stratum basale

Mitotic figures are seen due to continuous cell division of keratinocytes

malpighian layer, spinous layer, prickle cell layer

what is the other term for stratum spinosum?

stratum spinosum

Cuboidal or slightly flattened cells

stratum spinosum

Composed of several layers of polyhedral keratinocytes

stratum spinosum

Thicker in soles of the foot due to constant pressure

stratum spinosum

The keratinocytes in the deeper layers of the stratum spinosum still possess limited capacity to divide.

stratum spinosum

Prominent feature is the presence in the cytoplasm of numerous bundles of keratin

tonofibrils, tonofilaments

Microscopically visible bundles

desmosomes

this is where tonofilaments end and insert

desmosomes

Under LM: appear as spine-like "intercellular bridges" (artifact of tissue preparation), giving the layer its name

tonofibrils, tonofilaments

Maintains cell cohesion (cell interaction)

granular layer

what is the other term for stratum granulosum?

stratum granulosum

It is due to the presence of dark cytoplasmic granules within the layer.

stratum granulosum

Consists of 3-5 layers of flattened polygonal cells (keratinocytes)

keratohyaline granules, profilaggrin

Cytoplasm contain large granules with irregular shape called ???? (most distinct feature), which contain ???? that helps aggregate keratin filaments

keratohyaline granules

what is the most distinct feature of stratum granulosum?

profilaggrin

it hepls aggregate keratin filaments

lamellar (lipid) granules

release lipids into intercellular spaces to form a barrier against water loss and substance entry

stratum granulosum

Undergo terminal differentiation process of keratinization

stratum granulosum

Keratinocytes in this layer no longer divide and are already dead.

clear layer

what is the other term for stratum lucidum?

stratum lucidum

A layer of thin, translucent, lightly stained, refractile cells

stratum lucidum

Layer is apparent in thick skin; NOT identifiable in the thinner skin

stratum lucidum

Consists of 4-6 rows of very flat, dead, and anucleate keratinocytes

stratum lucidum

Nuclei begin to degenerate in the outer row of the stratum granulosum; nuclei are rarely seen in the stratum lucidum

horny layer

what is the other term for stratum corneum?

stratum corneum

Outermost layer of the epidermis that holds dead skin cells

stratum corneum

Consists of 15-20 layers of flattened non-nucleated heavily keratinized cells

stratum corneum

Cytoplasm is filled with keratin filaments embedded in an amorphous matrix

stratum corneum

Superficial cells (squames) form the stratum disjunctum and are continuously shed (desquamation)

melanocytes

Specialized cells in the basal layer or in the underlying dermis

melanocytes

Arise from the neural crest

melanocytes

Comprise about 7-10% of epidermal cells (second most numerous after keratinocytes)

stratum basale, stratum spinosum

where is melanocytes usually found?

melanin synthesis and pigmentation

Produce melanin pigment responsible for the pigmentation of the skin and hair (also present in the uvea of the eye).

melanin

is synthesized from tyrosine through the action of the enzyme tyrosinase inside the melanosomes (membrane-bound granules).

melanin synthesis and pigmentation

Melanin production is influenced by genetics and UV exposure

eumelanin, pheomelanin

what are the two key types of melanin?

eumelanin

More abundant and most common form of melanin

eumelanin

brown to black pigment, provides strong UV protection

pheomelanin

Sulfur-containing pigment

pheomelanin

red to yellow pigment, less effective at UV protection

melanogenesis

eumelanin and pheomelanin are produced by ??