information about skin

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Understanding the Skin structure
One of the most important aspects of high Skin Care, is to understand the constituents of the skin itself, this learning helps to achieve better results in choosing the correct products for your specific problem or goal and also helps one to treat ones skin better with a more in-depth knowledge and greater understanding.
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Structure of the Skin
Outer layers
(a) Epidermis - most superficial
(b) Dermis
(c) (Hypodermis/Subcutaneous Tissue)
information about skin A_104

Epidermis
Five layers
Stratum Germinativum (Basal Layer)
Stratum Spinosum (Prickly Layer)
Stratum Granulosum (Granular Layer)
Stratum Lucidum
Stratum Corneum (Horny Layer)
Stratum Germinativum (Basal Layer)
Innermost layer to the Dermis
Separated from the underlying Dermis by a basement membrane
Cuboidal shaped cells, with large nuclei & distinct cell content, particularly Ribosome's for Keratin production
Mitotic activity most evident in this layer, replacing cells in upper layers
Approx 14 days for cells to move through this layer
As the cells hit the upper part of this layer, they increase the amount of Keratin in them as Keratin granules
Melanocytes are scattered throughout this layer which synthesize the black pigment Melanin
Stratum Spinosum (Prickly Layer)
This second layer is sometimes considered to be part of the st. germinativum.
Polyhedral shaped cells held together by intercellular bridges (or prickles) but become flattened towards the top
Prominent nuclei and cytoplasmic basophilia indicate active protein synthesis
A fibrillar protein aggregates in these cells to form intracellular fibrils known as tonofibrils which converge upon the desmasomes of the prickles. These tonofibrils become more prominent toward the st. granulosum
Stratum Granulosum (Granular Layer)
Third layer
Contains melanocytes and basophilic granules which are thought to be the precursor to Keratin
Flattened and diamond shaped cells which are characterized by numerous, dense basophilic granules which crowd the cytoplasm and tend to obscure the tonofibrils
Stratum Lucidum
Questionable fourth layer which is often so thin that it is sometimes considered not to be a transitional layer between the st. granulosum and the st. Corneum
It is so thin that there is debate currently that the layer is an artefact of the electron microscope and doesn’t in fact exist
Supposedly most pronounced in the palms of the hands and the soles of the feet
Cells show signs of disintegration and have lost their nuclei and organelles
Stratum Corneum (Horny Layer)
Final layer or the Horny layer
Cells are non-nucleated disintegrated, fused, flattened squamous cells which are filled with Keratin fibres (matured Keratin)
Little water
Forms the protective barrier for the skin
As the junctions become interrupted, the cells are desquamated
Dermis
Contains two layers
Papillary Layer which is closest to the Epidermis
Reticular Layer
Papillary Layer
Consists of loose connective tissue with fine Collagen and Elastin fibres
Folded into ridges or papillae which extend in to the Epidermis
Especially noticeable in the palms and soles (fingerprints)
Contains nerve fibres and blood vessels which extend into the folds, supplying the Epidermis which is avascular
Rete pegs (?)
Reticular Layer
No defined boundary between the two layers
Contains denser connective tissue and many thick Collagen fibres
(Hypodermis)
Technically not part of the skin
Composed of loose connective tissue and contain lots of Adipose Tissue for metabolism, insulation,
Terminology
description - colour, shape, number, size, grouping