Term
| How large is the skin relative to other organs (ranking it)? What percentage of the body mass does it make up? |
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Definition
| Skin is the largest organ in the human body and accounts for 7% of our weight. |
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Term
| How many layers of skin are there and what are they called? What are each layer made of, in terms of tissue type? |
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Definition
| 2 distinct layers: epidermis (stratified squamous epithelium) and dermis (CT) |
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Term
| What is the hypodermis? What is it made of and where is it located? Finally, what does it do? |
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Definition
Another layer deep to the skin, just deep to the skin (so it's distinct from the skin) and composed of loose areolar and adipose CT.
The purpose of the hypodermis is to anchor the skin to the rest of the body and provide an insulatory layer. |
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Term
| What is another name for the hypodermis? |
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Definition
| superficial fascia and subcutaneous layer |
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Term
| What are the main functions of skin? |
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Definition
| Cushioning/insulating deeper organs, protecting body from heat/cold/chemicals/cuts, regulating body temperature, acting as a mini-excretory system, screening out UV rays, making Vitamin D |
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Term
| What are the layers of the epidermis, superficial to deep? |
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Definition
From superficial to deep:
Stratum corneum
Stratum lucidum (only in thick skin)
Stratum granulosum
Stratum spinosum
Stratum basale (stratum geminativum) |
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Term
| Describe the cells inside and what each layer of the epidermis is like. |
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Definition
Stratum corneum is just flattened (squamous) dead cells (keratinocytes) that are filled with keratin.
Stratum granulosum is flattening, dying cells (keratinocytes) that have cytoplasms filling with keratohyalin granules.
Stratum spinosum is where there are live keratinocytes that are making bundles of intermediate pre-keratin filaments.
Stratum basale is the basal layer of the epidermis, where keratinocytes there are fast-replicating stem cells and making new stem cells for the upper layers, and melanocytes are there making melanin to protect the DNA of the keratinocytes above. Finally, Merkel cells that pertain to nerves are there. |
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Term
| What is the most common type of skin cell? |
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Definition
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Term
| What are the two layers of the dermis? Describe them (composition, etc.) |
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Definition
Papillary layer, made up of loose areolar connective tissue.
Reticular layer, which is 80% of the dermis, and made up of dense irregular CT. |
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Term
| How vasculated/innervated is the dermis? |
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Definition
| Very much so in both regards |
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Term
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Definition
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Term
| What are the key parts of hair? |
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Definition
Shaft-projects above the skin surface
Root-embedded in the skin |
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Term
| Where are sebaceous glands, what do they do? |
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Definition
Occur over entire body except palms and soles, associated with hair follicle
Secrete sebum – an oily substance (functions of sebum are to collect dirt, and to soften and lubricate hair and skin) |
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Term
| Sweat glands-what do they do, where are they located, what types are there? And what the hell is sweat? |
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Definition
Sweat first off is 99% water, with some salts (less than blood) and some metabolic wastes in there.
Eccrine sweat glands are found mostly everywhere on the body and are the most numerous and produce true sweat.
Apocrine glands are confined mostly to the genitals and ass and make special musky sweat and phermones. |
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Term
| How do you classify the various degrees of burns? Be specific. |
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Definition
1st degree burn: only upper epidermis damaged
2nd degree burn: upper part of dermis also damaged, blisters appear but skin heals with little scarring
3rd degree burn: consumes thickness of skin (so dermis too), skin appears white, red, or blackened and requires skin grafts to heal in a reasonable timeframe |
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Term
| Types of skin cancer and what cells give rise to them |
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Definition
Basal cell carcinoma arises from the cells in the stratum basale, and is the most common and least dangerous.
Squamous cell carcinoma arises from the keratinocytes of the stratum spinosum.
Melanoma is the most dangerous type of skin cancer and arises from the melanocytes. |
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