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What is the epidermis made out of and where is it thickest?
Stratified squamous keratinizing epithelial tissue and thickest on psalms and soles
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Define keratinizing?
The protein keratin is produced and surface cells are dead
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What are squamous epithelial tissue?
- Made of many layers of flat cells
- Mitosis takes place in the lower layers to replace the skin that has worn out at the top layer
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What happens in the stratum germinativum?
- Lowest layer
- Mitosis takes place here, pushes older cells toward the skin surface
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What are Merkel cells?
They are receptors for the sense of touch
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Why are the cells at the top dead?
Because they have moved to far from the the capillaries and have no nutrients
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How is vitamin D produced?
- It is produced by living keratocytes who produce a cholesterol
- that with exposure to UV light turns to vitamin D
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What do you call the outer most layer?
Stratum corneum
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What makes the skin water proof?
The presence of keratin as it prevents the entry of water
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What is a first degree burn?
- A burn where only the superficial skin is burnt
- Appears red due to vasodilation in the damaged area
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What is a second degree burn?
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What are Langerhans cells?
They are dendritic cells
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Where are melanocytes found
in the lower epidermis?
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What is the function of melanocytes?
Produce a protein, pigment called melanin on exposure to UV light
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The function of dendritic cells?
They are antigen-presenting cells, they present it to the surface of t-cells
- Phagocytize foreign material
- and stimulate an immune
- response by lymphocytes
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What is the dermis made up of?
An irregular type of connective tissue
Strength and elasticity are characteristics
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What do the call the junction between the dermis and epidermis?
- the papillary layer
- Capillaries are abundant here to nourish not only the
dermis but also the stratum germinativum.
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Name all the layers of the integumentary system
Stratum corneum, lucidum, granulosum, spinosum, basale
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What is the appearance and function of the stratum spinosum
Appears to be covered in thorn like spikes, providing the skin with strength and flexibility
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What is the appearance and function of the stratum granulosum?
- Site of keratin formation
- has keratinocytes
- keratohyalin gives it it's granular appearance
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Where is the stratum lucidium found?
- In the soles, palms and fingertips.
- Made up of dead keratinocytes
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What provides water repellent action?
the Lamellar granules, they are continuously shed and replaced
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What do langehanns cells do?
- Regulate immune reactions in the skin
- Ingest antigens and present them to the cells of the immune system
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What is the dermis tissue composed of?
Connective tissue, blood vessels, nerves, glands and hair follicles
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What are the cells in the epidermis?
- Keratinocytes
- Merkel cells
- Langerhans cells
- Melanocytes
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What do the elastic fibres in the dermis help with?
strength and elasticity
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What is the subcutaneous tissue made up of?
an insulating layer of fat and blood vessels
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What is the function of the subcutaneous tissue?
Maintain body temperature and offers protection to all the organs
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What are the sweat glands used for?
thermoregulation
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What is the function of hair?
Protection, thermoregulation and sensing light touch
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What is hair composed of?
elongated dead keratinized cells that are bound by extracellular proteins
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Where is hair not found?
Found everywhere on human body except palms, soles, lips, nipples, parts of external genitalia, and distal segments of fingers and toes
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What is the hair shaft?
the superficial portion that extends out the skin
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What is the hair root?
the portion that penetrates the dermis
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