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91 Cards in this Set
- Front
- Back
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What is the skin? |
An organ which forms the principle interface between the external environment and the body's organs |
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What are the three layers of the skin? |
The epidermis, dermis, and hypodermis |
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What are the main functions of the skin? |
Protection of the internal organs from environmental hazards like microorganisms Preventing heat and water loss Cutaneous sensation Metabolic synthesis (vitamin D) Blood reservoir |
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What layers of the skin are vascularized? |
The dermis and hypodermis |
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What differentiates the epidermis from the other layers of skin? |
It is avascular |
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Why is it necessary for the epidermis to be avascular |
So that accessory skin structures can exit to the environment |
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How many cell types are in the epidermis? |
4 |
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What cell types are found in the epidermis? |
Keratinocytes, melanocytes, langerhans cells, and merkel cells |
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How many layers does the epidermis have? |
4-5 |
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What are the layers of the epidermis? |
Top to bottom, stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale CLGSB |
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What is the primary component of the epidermis? |
Keratinocytes |
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From where do keratinocytes arise? |
The basal layer, from stem cells |
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What is the function of keratinocytes? |
Dead keratinocytes accumulate and form detachable barrier layer |
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What are melanocytes? |
Cells which provide pigment to the skin |
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In which layer of the epidermis are melanocytes found? |
The stratum basale |
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What layer of the epidermis is the largest? |
The stratum spinosum |
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Why is the stratum granulosum so named? |
Because it consists of keratinocytes containing lamellar granules |
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What is the structure of melanocytes? |
Cell bodies in the basal epidermis which branch out amongst keratinocytes and leak melanin granules into them |
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What are the forms of melanin? |
Eumelanin and pheomelanin |
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What form of melanin is darker? |
Eumelanin |
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What happens to skin when it is exposed to UV radiation? |
It produces more melanin |
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What is a melanosome? |
A protruding extension of a melanocyte which branch out between keratinocytes and give them color |
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What are Langerhan's cells? |
A cell which presents dendritic antigens |
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What is the function of Langerhan's cells? |
To bind and present antigens entering through the skin, provoking an immune response |
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What are Merkel cells? |
Cells which connect the epidermis to a nerve terminal |
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What is the function of Merkel cells? |
To act as touch receptors and support cells |
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Where are Merkel cells found? |
In the stratum basale of the epidermis |
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Where are Langerhan's cells found? |
In the stratum basale of the epidermis |
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How long does it take for cells to migrate through the epidermis? |
20-30 days |
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What is vital for maintenance of the epidermis? |
Layers of production and shedding must be equal |
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What is the difference between thick and thin skin? |
Thin skin does not contain a stratum lucidum and all of its epidermal layers are much smaller |
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How does skin in the womb differ from the skin of a newborn? |
Skin in the womb is completely sterile |
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What is true about most of the bacteria on skin? |
It is gram positive |
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What risk do skin microbes present? |
Can be dangerous to immunocompromised individuals |
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What layers exist in the dermis? |
The papillary and reticular layers |
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What is the main component of the dermis? |
Tough connective tissue (collagen) |
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What is the papillary dermis? |
A thin ridged layer of connective tissue adjacent to the epidermis |
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What is the reticular dermis? |
The thick layer of connective tissue which enables the elasticity, extendibility, and strength of the skin |
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Label the following picture: |
1: Epidermis 2: Hair follicles 3: Sweat glands 4: Nerve 5: Blood vessel 6: Reticular dermis 7: Papillary dermis |
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Determine which is thin and which is thick skin: |
Left is thick skin, right is thin skin |
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What type of skin is this? |
Thick skin |
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What type of skin is this? |
Thin skin |
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Where in the skin do hair follicles and sweat glands originate?
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The dermis |
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What create ridges in the papillary dermis? |
The dermal papillae |
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Which layer of skin is responsible for fingerprints? |
The papillary dermis |
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What cells exist in the dermis? |
Fibroblasts, dermal dendrocytes, other immune cells |
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What is the function of fibroblasts in the dermis? |
To synthesize and deposit collagen |
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Where in the skin is collagen created? |
In the dermis by fibroblasts |
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What is the purpose of dendrocytes in the dermis? |
To present antigens and contribute to wound healing |
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What cells in the dermis aid wound healing and present antigens? |
Dendrocytes |
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What are dermal corpuscles? |
Accumulation of neurons in the dermis which process sensory information |
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What are Pacinian corpuscles? |
Pressure sensitive receptors in the dermis |
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What are Meissner corpuscles? |
Touch sensitive receptors in the dermis |
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What are Ruffini corpuscles? |
Heat sensitive receptors in the dermis |
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What type of corpuscles sense heat? |
Ruffini corpuscles |
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What type of corpuscles sense touch? |
Meissner corpuscles |
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What type of corpuscles sense pressure? |
Pacinian corpuscles |
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What is the hypodermis? |
The layer of skin beneath the dermis which supports the upper layers and anchors them to the body |
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What is the hypodermis composed of? |
Fat cells and connective tissue |
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What types of cells exist in the hypodermis? |
Adipose cells, fibroblasts, macrophages |
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What are the three components of hair? |
Hair follicle, sebaceous gland, and hair muscle |
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What are the three phases of hair growth? |
Anagen, Catagen, and Telogen |
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What happens in the anagen phase of hair growth? |
Growth |
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What happens in the catogen phase of hair growth? |
Atrophy |
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What happens in the telogen phase of hair growth? |
Rest |
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What gives hair its color? |
Melanocytes in the follicle |
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What causes red hair? |
An inability to produce eumelanin |
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What causes gray hair? |
A reduction in melanocyte numbers as we age |
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What is a nail? |
A dead keratinsized plate which covers the finder and toe tips |
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What is the function of the finger and toenails? |
Both to protect the fingers and toes and aid dexterity |
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What types of sweat glands exist? |
Eccrine, apocrine, and sebaceous |
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Where do eccrine sweat glands open? |
Into the skin |
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Where do eccrine sweat glands originate? |
The dermis |
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Where are eccrine sweat glands located in relation to hair follicles? |
In between |
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What is the structure of eccrine sweat glands? |
Simple tubular structures |
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Where are apocrine sweat glands located in relation to hair follicles? |
Open onto hair follicle |
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Where do apocrine sweat glands open? |
Hair follicles |
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Where in the body are apocrine sweat glands located? |
The armpits and groin |
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Where in the body are sebaceous sweat glands located? |
Everywhere but the palms and soles |
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What do sebaceous glands secrete? |
Sebum |
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What is the purpose of epidermal stem cells? |
Everyday regeneration of epidermal layers |
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How is the hair follicle regenerated? |
Multipotent stem cells which supply the cells which renew hair follicles |
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Why is it important that the stem cells in the hair follicle are multipotent? |
Because they can also differentiate to regenerate the epidermis and sebaceous glands in response to injury |
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Why are melanocyte stem cells necessary? |
Because melanocytes die during the catagen phase of hair growth |
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Why is it important that melanocyte stem cells in the hair follicle are multipotent? |
Because they can also differentiate to regenerate the melanin in the epidermis |
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What is the effect of sunburn? |
Damage to cell DNA (thiamine-thiamine dimers) |
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What parts of the body's DNA are damaged in sunburn? |
Thiamine-thiamine dimers |
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What happens in response to DNA damage by UV radiation? |
Inflammatory response-- redness, swelling, pain |
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What causes peeling after a sunburn? |
Apoptosis of severely damaged cells |
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What is the main function of sweat glands? |
Thermoregulation |
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What are the primary accessory structures of the skin? |
Hair, nails, and sweat glands |
