Histology: Skin and Glands Flashcards
Which of the following is not a normal function of skin: Physical barrier, energy reservoir, wound healing, thermal regulation, acid-base balance, excretion of metabolic production and initiation of immune responses.
Acid-base balance. This is controlled by the lungs and kidneys.
What layer of the epidermis is most metabolically active?
Stratum basale. It is actively dividing and producing stem cells that will differentiate and migrate apically in the epidermis.
What proteins link the epithelial cells of the stratum spinosum?
Tonofilaments weave in and out of desmosomes. They are composed of intermediate filaments and keratin.
What transition occurs in epithelial cells from the stratum granulosum to the stratum corneum?
The cells in the stratum granulosum lose their internal organelles and keratohyalin granules cross-link within the cell to make them keratinocytes.
What forms the water barrier in the epidermis?
Lamellar body secretion. An impermeable lipid layer forms in the upper stratum granulosum.
Why do epithelial cells need channels between one another?
Epithelium does not have vasculature and this is how cells get their nutrients.
At what epithelial layer does mitosis cease?
Stratum Spinosum
What type of cells are in the stratum basale?
Progenitor
In a histological stain, what part of the epidermis comes out clear and why?
The stratum lucidum. It is a thin layer of lipids and lipids stain clear.
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Thick skin. Found on soles of feet and palms of hands. Note thicker layer of stratum corneum and stratum lucidum.
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Thin skin. Note hair follicles in dermis and hypodermis.
What are the two layers of the dermis?
Papillary and Reticular
What holds the dermis and the epidermis together?
Hemidesmosomes and connective tissue in the papillary layer
How can you differentiate the papillary layer from the reticular layer of the dermis?
The reticular layer has dense collagen bundles.
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Langerhans cells in the epidermis. These dendritic cells will migrate out of the skin when they come in contact with a pathogen to initiate immune responses.
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Melanocyte pushed into epithelial layer.
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Melanocytes
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Capillary in dermis that allows for thermoregulation.
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Lower portion is the secretory piece where sweat is produced and the upper arrows are the ducts where the sweat is secreted.
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Sweat gland. D regions secrete proteins of sweat, L regions secrete the fluid component of sweat and My are myoepithelial cells that squeeze the sweat out of the gland.
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Two different cell types of the sweat gland. Darker staining cells secrete the proteinaceous part of sweat and the lighter staining cells secrete the liquid part of sweat.
Pathway of sweat getting to the surface of your skin.
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What six structures allow your body to sense vibration and pressure in the skin?
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Merkel Cell. Notice small processes into keratinocytes.
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Pacinian corpuscle. Senses vibration, pressure, and rapid changes in tissue state. Looks like an onion.
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Meissner’s Corpuscle. Senses movement and low frequency vibration. Note that it looks like a tornado where papillae wrap around the axon.
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Hair follicles and sweat glands. The epidermis will extend all the way down to form the hair follicle. Note the brown portion in the center of the hair follicle which is the hair shaft.
Various parts of the hair follicle.
*Outer/inner root sheaths, cuticle, cortex, medulla, and melanocytes
What different ways do glands secrete their content?
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5 Layers of the epidermis
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Cells in the stratum spinosum linked by desomosomes.
*What is the dark staining region?
Keratohyalin granules in the stratum granulosum
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- Stratum corneum 2. Stratum lucidum 3. Stratum granulosum
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- Papillary layer 2. Reticular layer (note dense collagen bundles)
