Integumentary system 8 & 9 Flashcards
What parts of the body does the integumentary system cover?
Skin, nails, and hair.
What are the 2 main parts in the structure of the skin?
Epidermis - surface epithelial layer
Dermis - deeper connective tissue layer
What is deep dermis referred as, & is it part of the skin?
It is known as either subcutaneous layer, superficial fascia or hypodermis & is not part of the skin.
What are the four cell types that compose the epidermis?
keratinocytes (major), melanocytes,
langherans cells,
Merkel cells.
What percent of epidermal cells are composed of keratinocytes?
90%
What are functions of keratinocytes in the epidermis?
To produce keratine,
protect skin,
waterproof skin.
How many layers are in the epidermis?
four to five strata/sub layers.
What is the order of layers in the epidermis?
Stratum basale,
stratum spinosum,
stratum granolosum,
stratum comeum.
Describe the stratum basale (first layer of epidermis).
Single layer of low columnar or cuboidal cells at the base of the epidermis (basal layer).
These are the stem cells of the epidermis.
How long does it take to renew the epidermis?
3-4 weeks.
Describe the stratum spinosum ( second layer of epidermis).
Several layers of polyhedral cells joined by many desmosomes (specialised cell junctions that increase adhesion.
8-10 cell layer.
Describe stratum granulosum.
increase in keratin,
Where nuclei begins to degenerate.
includes lamellar granules=waterproofing liquid.
Cytoplasm contains many fine grains of keratohyalin granules, was do these do?
Keratohyalin granules release their lipid contents into the interstitial space, this acts as a protective barrier.
Describe stratum lucidum.
Cannot be identified in thin skin.
Several layers of flattened cells.
Nuclei are hardly visible.
what layer is the reason the body is protected by the epidermis.
stratum corneum.
what does stratum corneum consist of?
several layers of flattened keratinised (dead) cells.
what does stratum corneum do?
cells shed and are replaced from below, mostly keratin filled.
What can thick skin also be called.
Friction skin or glabrous (smooth) skin.
What do melanocytes do
produce melanin.
transfer pigment to keratinocytes.
8% of epidermal cells
describe lanerhans cells
form a defensive network in the epidermis.
found in the stratus spinosum.
phagocytic cells that engulf foreign materials, that invade the epidermis.
In contact with an antigen, migrate out of the epidermis and skin to lymph nodes.
Where are Merkel cells found.
stratum basale.