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20 Cards in this Set
- Front
- Back
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Functions of the skin
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Protection
Thermoregulation Sensation Metabolic |
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Skin is composed of...
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Epidermis
Dermis Hypodermis (subcutaneous tissue, superficial fascia) Skin apprendages |
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What type of tissue is the epidermis?
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Stratified squamous keratinized epithelium
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What cell types are in the epidermis?
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Keratinocytes:
Basal, Spinous, granular, Horney cells Non-keratinocytes: Melanocytes, Langerhans cells, Merkel cells |
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How are spinous cells connected?
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Desmosomes: possess lots of ribosomes and tonofilaments.
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Describe keratin distribution across the epidermis
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Lower molecular weight keratin found in the basal layers, higher molecular weight keratin found closer to the surface. Each of these keratin molecules is encoded by a different gene, thus, the molecules can be used as markers of differentiation.
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Describe the changes that granular cells undergo to become Horny cells.
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Lysosomal enzymes digest everything in the cell except for the cytokeratin + tonofilament complex --> filamentous-amorphous matrix = keratin.
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What affects skin color?
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Carotene pigments in the subcutaneous fat
Number of blood vessels in the dermis and the oxyhemoglobin content Amount of melanin pigments in the keratinocytes |
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Langerhans cells
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No desmosomes
Antigen-presenting cells 400-1000/sq mm |
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Merkel cells
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Sensory receptors of the skin
In S. basale: palms and soles Detection: touch |
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Meissner's corpuscle
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Detection: light discriminating touch
In the dermis (fingertips, toes, lips, nipples) Encapsulated Specialized schwann cells and non-myelinated nerve fibers arranged in a spiral manner |
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Pacinian corpuscle
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Detection: pressure, vibration, and gross touch
In the hypodermis of palms and soles, and some genital organs Encapsulated Non-myelinated nerve fiber in the center Collagen fibers and fibroblast-like cells in the concentric layers Fluid-filled space |
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What structures allow for sensation in the skin?
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Meissner's corpuscle
Pacinian corpuscle Merkel cells Free intraepithelial nerve endings - extend as far as stratum granulosum - pain, itch, temp. |
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Thick vs Thin skin?
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Thick: Epidermis ~ 1mm, more sweat glands, NO HAIR FOLLICLES, No sebaceous glands
Thin: Epidermis ~ 0.1mm, Fewer sweat glands, hair follicles, sebaceous |
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Merocrine sweat glands
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Not associated with a hair follicle
Coiled tubular glands Myoepithelial cells, duct Makes hypotonic secretion |
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Apocrine sweat glands
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Simple cuboidal epithelium
-axilla, areola of nipples and genital regions -mostly merocine mechanism (misnomer!), except for maybe milk secretion -begins to function at puberty -secretion is viscous and milky containing lipid, carbohydrate, protein, ammonia, ferric ions, short chain fatty acid --> acted on by bacteria |
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Sebaceous gland
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Begin at puberty
Testosterone i men Ovarian hormones and adrenal androgen in women Secretes Sebum: lipid-like substances Holocrine secretion Replacement of cell loss by mitosis |
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Describe the structures in a hair follicle
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Hair bulb:
-hair root -hair matrix (lots of melanocytes) -melanin Dermal papilla -induces hair formation; injury results in loss of hair -lots of nervous tissue |
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What determines hair color?
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Hair color is controlled by activities of the
melanocytes. Black, brown and yellow melanins in various combinations give the final hair color. People with blond or red hair carry the genetic trait to produce melanin which contains the sulfur-rich amino acid cysteine. |
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Describe the phases of hair growth
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Growth phase, Involution phase, resting phase
Scalp hair: long growth phase; short resting phase Eyebrows, eyelashes body hair and pubic hair - short growth phase; long resting phase |
