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Skin
Skin- Dr. Etemadi
61
Medical
Professional
08/26/2011

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Term
Basic organization of body system
Definition
1. Cell
2. tissue
3. organ
4. organ system
5. body
Term
What is the largest and heaviest organ in your body?
Definition
skin
Term
What is the function of skin?
Definition
protection, absortpion, secretion, organ of sense, and thermo-regulation
Term
What substance is secreted from the skin?
Definition
sweat and sebum
Term
Where is thick skin found?
Definition
palm and soles
Term
Where is thin skin found?
Definition
eyelid, medial side of the arm, and almost the rest of the body.
Term
What are the layers of the epidermis?
Definition
1. Stratum Basale or germinativum
2. Stratum spinosum
3. Stratum granulosum
4. Stratum lucidum
5. Stratum corneum
Term
What are the layers of the dermis AKA corium?
Definition
1. Papillary layer
2. reticular layer
3. hypodermis or superficial fascia
4. deep fascia or epimysium
Term
WHat separates the epidermis from the dermis?
Definition
The basement membrane and the basal lamina
Term
What is a major feature of the hyodermis AKA superficial fascia?
Definition
This CT layer is infiltrated with fat cells.
Term
What type of CT makes p the 2 layers of the dermis?
Definition
papillary layer is made of loose CT and the reticular layer is made of dense CT. both contain type I collagen
Term
the four major types of cells found in the epidermis
Definition
1. keratinocytes (most numerous)
2. Melanocytes (found on the basement membrane)
3. Langerhan cells (found within the straum spinosum)
4. Merker cells (found along the straum basale)
Term
describe the staining property of keratinocytes
Definition
basophilic due to the number and activity of ribosomes
Term
characteristics of stratum basale
Definition
It is a layer of the epidermis this is found at the bottom and is made of simple columnar epithelium. The cells are attached to each other by desmosomes and to the basal lamina by hemi-desmosomes.
Term
Characteristics of stratum spinosum
Definition
It is located above the straum basale and is made up of layers of increasingly flattened cells. These cells are attached to each other's spiny processes by intercelluar bridges called tonofibrils that are attached to extensions of other cells by desmosomes.
Term
WHat makes up the stratum malpighi?
Definition
the stratum basale and the stratum spinosum
Term
Characteristics of stratum granulosum
Definition
Only a few layers of flat cells. the cells are filled with keratohyalin like in the stratum spinosum. the extracelluar space is filled with lipid which creates a water proof seal.
Term
characteristics of the stratum lucidum
Definition
a thin layer of lightly staining very flat cells. usually only found in thick skin. the nuclei is barely visible. The intermediate filaments and the cellular matrix for immature keratin called eleidin
Term
characteristics of the Stratum corneum
Definition
made up of several layers of dead flat anucleated cells filled with soft keratin. this layer is constantly exfoliating
Term
the lenghth of time it takes a cell of the stratum basale to reach the stratum corneum
Definition
3 to 4 weeks
Term
the 3 components that determine skin color
Definition
1. oxyhemoglobin- gives the skin a red tint
2. caroten- gives the skin a yellow tint
3. melanin- gives the skin a brown to black pigment
Term
What do melanocytes produce and during development from what do they arise?
Definition
produce melanin and develop from neural crest cells
Term
Characteristics of melanocytes
Definition
1. they have a round body with irregular extensions that branch between the keratinocytes.
2. they are not attached to adjacent keratinocytes
3. are attached to the basal lamina via hemidesmsomes
Term
melanin synthesis
Definition
1. TYROSINE which is synthesized on ribosomes and RER and the GOLGY of melan0cytes
2. Tyrosine is converted to 3-4 DIHYDROXYPHENYLALANIN (DOPA). This reaction is the result of enzyme TYROSINASE activity.
3. DOPA is converted to dopaquinne
4. THen after several transformations dopaquinone is converted to melanin
Term
Cytocrine secretion
Definition
the process by which fully formed melanin granules (melanosomes) are transferred from melanocyte extensions into keratinocytes.
Term
How do melanocytes appear on an H&E stain
Definition
they appear look pale because the melanin granules are in the kerantinocytes. This the way the dermis protects the bodt from UV light damage
Term
Tanning
Definition
darkening of the skin after exposure to UV light of sun, (UVB and UVA) is due to rapid production of melanin in the melanocytes. Chronic exposure to sun light is proved to cause serious damage and tumors of the skin.
Term
Albinism
Definition
a hereditary disease, is the absence of TYROSIINASE activity and melanin can not be formed in melanocytes, and causes generalized pale skin and hair and lack of melanin in other parts of the body such as iris of the eye.
Term
Vitiligo
Definition
localized or sometimes generalized depigmented skin, due to absence or hypofunction melanocytes
Term
MELSMA or CHLOASMA
Definition
pregnancy mask, hyperpigmention of skin; specially face, during pregnancy due to hormonal changes during pregnancy.
Term
ADDISON DISEASE
Definition
hypofunction of adrenal gland and increase ACTH and causes hyperpigmentation of the skin. This might very well be due to stimulation of melanocyte stimulating factor.
Term
Langerhans Cells
Definition
dendritic cells found in the stratum spinosum, that act as antigen presenting cells.
Term
Merkel Cells
Definition
Found in the basal layer of mostly thick skin.
the free nerve endings that pass from the basal lamina to the epidermis helps to feel sensation in the skin
act as mechanoreceptors
Term
describe the layers of the basal lamina snd membrane and the type of collagen found
Definition
composed of 2 basale lamina and a basement membrane.
Type IV collagen is found in the basal lamina
Also Proteoglycans dermatan and heparan sulfate make up the ground substance
Term
WHat type of collagen anchors the basal lamina to the underlying CT?
Definition
type VII Collagen
Term
A disease that is caused by an increase proliferation of cells of the stratum basale and a decrease cycle time of epidermal cells, causing epidermal thickness and patched of silvery scales of epidermis
Definition
psoriasis
Term
A disease that is characterized by the development of groups of vesicles and bullae, autoantibodies IgG are produced against the desmosomes of the epidermis
Definition
pemphigus
Term
What kind of skin disorder occurs when IgG antibodies are made against the basal lamina and cause a separation of the whole epidermis from the dermis.
Definition
bullous pemphigoid
Term
Describe the circulation of blood in the dermis and how it contributes to thermoregulation?
Definition
the superficial plexus provides nurishment to the epdiermis and it is located in the papillary layer.
There is also a venous plexus deeper in the dermis that has arteriovenous anastomoses that has metarterioles with sphincters.

When you are cold the sphincters are closed blood can't flow to the skin, this keeps the warm blood closer to the interior
Term
The direction of the of fibroblast produce what and why are they important?
Definition
langer or tension lines/ they are important in performing surgeries to help wound healing and will decrease scar formation.
Term
What are the encapsulated nerve ending of the skin and what do they detect?
Definition
pacinian=pressure
Meissner=touch
Ruffini=heat
bulb of Kraus=cold
Term
Which diseases are caused by 2 of the mucopolysacharidosis that the ground substance of the dermis is affected?
Definition
Hurler's and Hunter
Term
A syndrome that occurs when there are various defects in collagen causing laxity and hyperextensibility of the skin and ligaments
Definition
Ehler's-Danlos
Term
laxity of the dermis
Definition
cutis laxa
Term
the hardening of dermis
Definition
scleroderma
Term
loosening of the skin is caused by
Definition
aging and cutis laxa
Term
THe invaginations of the epidermis from which hair develops
Definition
hair follicles
Term
the 3 layer of the hair that comes out of the skin surface
Definition
medulla, cortex, and cuticle
Term
What are the 3 phases of hair growth and how long do they last?
Definition
growing phase, anagen, continuous growth, last about 900 days
Regression phase, catagen, lasts 100 days
Resting phase, telogen, lasts 50-100 days
Term
What is located on the tip of the bulb of the follicle
Definition
melanocytes
Term
What is it called when hair falls out after pregnancy and possibly after an acute fever?
Definition
telogen efluvian
Term
What causes male pattern alopecia?
Definition
androgenic effects of male hormones
Term
Where does nail growth occur from
Definition
the nail matrix
Term
the type of holocrine glands that are found in the hair follicle and produce sebum made of lipid, cholesterol, triglyceride, and squalene
Definition
sebacuous glands
Term
Are sebaceous glands controlled by a nerve?
Definition
No, they are hormonally controlled.
Term
When are sebacous glands activated and what can the cause
Definition
puberty/acne
Term
What are the 2 types of sweat glands?
Definition
Eccrine-found all over the body
Apocrine-appear after puberty
Term
What type of sweat gland produces a watery and clear secretion and does not smell. Mode of secretion is merocrine. Are innervated by cholinergic nerves
Definition
eccrine
Term
What type of sweat glands appear at puberty. produce a pigmented, slightly visid, and smells, the mode of secretion is apocrine. innervated by adrenergic nerves
Definition
apocrine
Term
The type of epithelia found in sweat ducts
Definition
stratified cuboidal
Term
the type of epithelia found in sweat glands
Definition
stratified columnar
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