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integumentary system
skin
Term | Definition |
---|---|
The skin: | Covers the entire body, largest organ of the body, thickness of 1.5-4 mm |
Skin consists of | Epidermis, dermis, hypodermis |
epidermis | superficial region consisting of stratified squamous epithelium tissue |
dermis | underline epidermis and consists of dense irregular connective tissue, strong flexible connective tissue, contains nerves and blood vessels, hair follicles and glands |
Hypodermis | Subcutaneous layer deep to skin, not part the skin but share some functions, mostly adipose tissue the acts as shock absorber and insulator |
kertionocytes | Tightly connected by desmosomes, arise from stratum basal (deepest layer of the epidermis), become scale like and die, death of cells occur from lack of blood |
Melanocytes | Synthesis melanin which protect the nuclear's from UV rays and shelters DNA, these cells are found in stratum basal, spider like |
Langerhan's cells | they are macrophages, they help to activate your immune system |
Merkel cells | Present in small numbers at the dermal-epidermal junction, immediately associated with the sensory nerves |
Layers of the epidermis are (5): | Stratum basale, stratum spinsum, stratum granulosum, stratum lucidum, stratum corneum |
Stratum Basale | Deepest epidermal layer also called germinitavum because of rapid cell growth, Single row of young keratinocytes |
Stratum Spinosum (pricky layer) | Several layers thick, cells contain web-like System of intermediate prekeratin filaments attached to desmosomes. |
Stratum Granulosum (granular layer) | 4-6 layers ( thin ), sell appearance is flattened |
Stratum Lucidum (clear layer) | Only in thick skin, thin, translucent band, a few rows of flat dead keratinocytes. This is only present on thick skin |
Stratum Corneum (horny layer) | 20 to 30 rows of dead, flat, enucleate keratinized membrane sacs, though dead- cells still have functions |
How many cells do we shed every minute | 50,000 |