What are the layers of the skin from the superficial to the deep?
Epidermis; dermis; hypodermis
What is contained in the Epidermis
The Stratum: Corneum, (Lucidum), Granulosum, Spinosum. (Luc. is in Thick skin)
Keratinocytes; Langerhans cells; Melanocytes; Merkel Cells.
What is contained in the Dermis
Layers: Papillary layer (Dermal Papillae); Reticular Layer.
Hiar follicle: Root hair plexus; Hair root, hair shaft, Sebaceous gland, Arrector pili muslce
Sweat Glands: Eccrine sweat gland; Apocrine Sweat gland.
Corpuslces: Miesner and Painian
What is contained in the Hypodermis?
Sweat Glands: Eccrine and Apocrine
Vessels: Cutaneous vessels
What are the main functions of skin?
Protection; Prevent dehydration; temperature regualtion; synthesis of viamin D3 and Sensory receptioin.
How is the skin a protection?
physical and chemical barrier against pathogen entry. initiate immune response(capture and present atigens, release cytokines). Prevent UV damage.
where would Thick skin be found in the body?
thick is called glabrous skin and found on hands (palms) soles, thick epidermis.
Where would thin skin be found?
Hairy skin is everywhere else that isn't the palms, soles.
what is the difference in thick and thin skin
Thick has a thick epidermis and Thin has a thin epidermis and no stratum lucidum.
the stratum granulosum is thin and the tratum corneum is thin.
But thin skin does have hairs, sebaceuos and eccrine glands.
what is a stratum lucidum
A space of the epidermis where there is more transparency in the cells ofter, where organelles start to disappear in the cells.
How do we get the differentiation of keritinized stratisfied epidermis of the skin?
what are the layers of the differentiating epidermis?
The Stratum basali; the stratum spinosum, the stratum granulosum, the stratum corneum. (Cute ladies get smart boys)
what do we find in the stratum basalis?
we find stem cells and hemidesmosomes to hold the cells to the bsement membrane
what is found in the stratum spinosum
lots of desmosomes to hold the cells together, and look a little spiny because of it.
what is found in the stratum granulosum
Karatohyalin granules: Keratin aggregation
Lamellar granules: lipid coating
what is found in the stratum corneum (describe it)
Anucleate then acellular layer of stacks (squames) of cross linked keratin coated with lipid.
Describe the way that warts take advantage of the normal development of skin
they ride the ascending layers of epithelium during Keritinocyte differentiation.
describe the location of the 5 stratums of epidermis in thick skin.
the stratum corneum is the most superficial, then the lucidum is a light line just below that. the granulosum is below that and followed by the spinosum and the basale is right next to the basement membrane
What is the significance of the Stratum basale
It is the source of stem cells, transit amplifying cells and links to the basal lamina by hemidesmosomes.
The cells here are connected by lots of desmisomes that look like pokey little things when stained
Deffects in this function can lead to defects in inflammatory diseases such as eczema and may contribute to asthma
the aggreated keratin filaments cross-linked together to form squames and serve as a scaffold for lipids and proteins that provide the barrier function
A protein involved in aggregating keratin in the stratum corneum (contained in keratohyalin granules
what do Langerhans cells do?
found in tratum spinosum, bind and process antigesn and migrate to lymph nodes or just to T cells in skin and are professional antigen presenting cell
Derived from neural crest, located in stratum basale, produce a substance too protect nuclei from UV
Produce melanin (in melanosomes); inject melanin granules into keratinocytes (cytokine secretion)
Thought to be mechanosensory cells, innervated by free nerve endings
Merkel Cells in the basal layer!
Two kinds of cancer of Keratinocytes:
Common one looks like darkly colored aggregates
Less common one is loops and layers of cells
Basal Cell Carcinoma (dark aggregates, associated with sun)
Squamous cell carcinoma (layers of squamous looking cells invading the tissue) also associated with sun
what is a meissner's Corpuslce?
they are like little Q-tip ends" that are in dermal papillae and give the tactile sense of light touch
what are the pacinian corpuslce?
deep in the dermis or in the hypodermis is the pacinian corpuslce that looks like an onion slice in the hypodermis and sense vibration,pressure.
What are the two types of sweat glands?
Eccrine and apocrine sweat glands
what are Eccrine sweat glands?
they are in dermis/hypodermis and secretion by membrane transport and merocrine (exocytosis) and then send fluid up through exritory duct that resorbs salt (basis of cystic fibrosis test)
what is an apocrine sweat gland?
in axillar, areolar, anal regions, secretion is merocrine (exocytosis) viscous secretion is initially odorless, but affected by bacteria.
What is the difference in the apperance of eccrine and apocrine sweat glands?
apocrine sweat glands have gigantic lumens!
what is a pilosebaceous unit?
the hair!!! and all of the root and folicle and the sebaceous gland.
what is the structure of sebaceous gland, and the type of secretion?
simple branched acinaar glands; holocrine secretion
what are the muscles that lift the hair cells?
the arrector pili muscles
what would you lose if you were to lose the hair follicles in a region?
you would lose the hair but also the stem cells that produce hair and also produce surface epidermis after wounds etc.!! they are a stem cell bank!
what are the souces of afferent nurological information in the skin?
merkel cells, free neurons, meissner's cells, and pacinian cells send info to the CNS (somatic sensory)
what is the efforent innervation of the skin?
sympathetic innervation to the apocrine glands, arterioles, arrector pili, and the eccrine sweat glands!
Cancer of the pigment cells, causes the most deaths from skin cancer.
Cancer of the cells that are thought to be sensory cells and innervated by free nerve endings
Merkel cell carcinoma.
What funcions could the circuitous interdigitations of the dermal papillae have ?
Mechanical strength; friction ridges!
What is the layer of Dermis that is made of Type III Collagen fine elastic fibers and lots of cells
What is the layer of the dermis that is made of type I collagen thick elastic fibers and few cells
where is the main blood supply in the skin?
in the dermis...the capillaries extend into the Dermal papilla...superficial plexus below and communicating vessels to the deep plexus