Skin LC Flashcards
In this image, identify the stratum spinosum!
Stratum Spinosum is the thickest layer in the epidermis. The cells in this layer actively synthesize keratins. It is just above the basal layer.
In this image, identify the dense irregular connective tissue!
The reticular layer of the dermis is much thicker than the papillary layer. The former is a dense irregular connective tissue, whereas the latter is a loose connective tissue. The reticular layer is mainly Type I collagen.
Human skin has a good capacity for repair. In fact, the epidermis is renewed every 15 to 30 days. In this image, identify the layer of the epidermis that contributes significantly to this renewal process.
The stratum basale is a single layer of basophilic cuboidal or columnar cells on the basement membrane at the dermal-epidermal junction. In this layer, mitotic activity can be brisk. Also in this layer, along with the deepest layer of the stratum spinosum, exists progenitor cells for all the epidermal layers.
The cells in the stratum basale are joined to the basal lamina via which of the followings?
Desmosomes
Actin
Hemidesmosomes
intermediate Filament
Cadherin
Hemidesmosomes in the basal cell membranes join these cells to the basal lamina, and desmosomes bind these cells of this layer together in their lateral and upper membranes.
In this image, pigmented epithelial cells are present. The first step in melanin synthesis is catalyzed by
Tyrosinase
Aminopeptidase
Arginase
Amylase
Lipase
Tautomerase
TYROSINASE
The first step in melanin synthesis is catalyzed by tyrosinase, a transmembrane enzyme in Golgi-derived vesicles. Tyrosinase activity converts tyrosine into 3,4-dihydroxyphenylalanine (DOPA), which is then further transformed and polymerized into the different forms of melanin. Melanin pigment is linked to a matrix of structural proteins and accumulates in the vesicles until they form mature elliptical granules about 1-μm long called melanosomes
Melanosomes are then transported via kinesin to the tips of the cytoplasmic extensions. The neighboring keratinocytes phagocytose the tips of these dendrites, take in the melanosomes, and transport them by dynein toward their nuclei. The melanosomes accumulate within keratinocytes as a supranuclear cap that prior to keratinization absorbs and scatters sunlight, protecting DNA of the living cells from the ionizing, mutagenic effects of UV radiation.
Although melanocytes produce melanosomes, the keratinocytes are the melanin depot and contain more of this pigment than the cells that make it. One melanocyte plus the keratinocytes into which it transfers melanosomes make up an epidermal-melanin unit. The density of such units in skin is similar in all individuals. Melanocytes of people with ancestral origins near the equator, where the need for protection against the sun is greatest, produce melanin granules more rapidly and accumulate them more abundantly in keratinocytes.
This squamous cells carcinoma likely arise from cells of the
Stratum Corneum
Stratum Lucidum
Stratum Granulosum
Stratum Spinosum
STRATUM SPINOSUM
Keratinocytes of the stratum spinosum are the neoplastic cells in squamous cell carcinomas.
This tumor in this image likely derives from cells of the
Stratum Corneum
Stratum Lucidum
Stratum Granulosum
Stratum Spinosum
Stratum Basale
Dermis
Subcutaneous Tissue
DERMIS
This is a benign hemangioma from the dermis, likely arising from native vessels of the dermis
Identify the epidermal ridges
Also known as the integument (L. integumentum, covering) or cutaneous layer, the skin is composed of the epidermis, an epithelial layer of ectodermal origin, and the dermis, a layer of mesodermal connective tissue. At the irregular junction between the dermis and epidermis, projections called dermal papillae interdigitate with invaginating epidermal ridges to strengthen adhesion of the two layers. Epidermal derivatives include hairs, nails, and sebaceous and sweat glands. Beneath the dermis lies the subcutaneous tissue or hypodermis (Gr. hypo, under + derma, skin), a loose connective tissue layer usually containing pads of adipocytes. The subcutaneous tissue binds the skin loosely to the underlying tissues and corresponds to the superficial fascia of gross anatomy.
Identify the dermal papillae
Also known as the integument (L. integumentum, covering) or cutaneous layer, the skin is composed of the epidermis, an epithelial layer of ectodermal origin, and the dermis, a layer of mesodermal connective tissue. At the irregular junction between the dermis and epidermis, projections called dermal papillae interdigitate with invaginating epidermal ridges to strengthen adhesion of the two layers. Epidermal derivatives include hairs, nails, and sebaceous and sweat glands. Beneath the dermis lies the subcutaneous tissue or hypodermis (Gr. hypo, under + derma, skin), a loose connective tissue layer usually containing pads of adipocytes. The subcutaneous tissue binds the skin loosely to the underlying tissues and corresponds to the superficial fascia of gross anatomy.
Identify the stratum corneum
The stratum corneum consists of 15-20 layers of squamous, keratinized cells filled with birefringent filamentous keratins. Keratin filaments contain at least six different polypeptides with molecular masses ranging from 40 to 70 kDa, synthesized during cell differentiation in the immature layers. As they form, keratin tonofibrils become heavily massed with filaggrin and other proteins in keratohyaline granules. By the end of keratinization, the cells contain only amorphous, fibrillar proteins with plasma membranes surrounded by the lipid-rich layer. These fully keratinized or cornified cells called squames are continuously shed at the epidermal surface as the desmosomes and lipid-rich cell envelopes break down.
Identify the layer that contains melanocytes
The stratum basale is a single layer of basophilic cuboidal or columnar cells on the basement membrane at the dermal-epidermal junction. The melanocytes reside in this layer and are specialized cells of the epidermis found among the cells of the basal layer and in hair follicles.
Which of the following is true with regards to albinism?
Congenital disorder due to a defect in tyrosinase
Hypopigmentation due to the decreased activity of melanocytes
Hypopigmentation due to the decreased activity of keratinocytes
Congenital disorder due to a defect in metaloproteinase
Congenital disorder due to a defect in tyrosinase
Albinism is a congenital disorder producing skin hypopigmentation due to a defect in tyrosinase or some other component of the melanin-producing pathway. An acquired condition called vitiligo involves skin depigmentation, often only in affected patches, due to the loss or decreased activity of melanocytes. The causes of melanocyte loss are not clear, but they may include environmental, genetic, or autoimmune conditions.
