Ch. 5 Integumentary System Flashcards
what does skin consist of?
1) epidermis (stratified squamous epithelium)
2) dermis (connective tissue)
3) hypodermis or sub cutaneous tissue (connective tissue)
what cells are part of the epidermis? (4) (KMLM)
1) keratinocytes (produces keratin)
2) melanocytes (produces melanin)
3) langerhans cells
4) merkel cells
what is the most common cell in the epidermis?
keratinocytes
where are melaninocytes located?
in the deep epidermis
what the langerhans cells part of?
the immune system
where are merkel cells located and what are they
deep in the epidermis and they are touch receptors
what do keratinocytes do?
form deep in the epidermis and shed at the surface
as cells pass through the epidermis what happens?
they change (keratinization)
how many epidermal layers are in thin skin?
4
how many epidermal layers are in thick skin?
5
what is considered thick skin?
palms, fingertips and soles
what is an example of keratinization?
large scales of epidermal tissue are sloughed off (psoriasis)
strata of the epidermis from deepest to most superficial
1) stratum basale
2) stratum spinosum
3) stratum granulosum
4) stratum Lucidum
5) stratum corneum
what is the only stratum of the epidermis to have thick skin?
stratum lucidum
how thick is stratum basale?
a single layer thick
what does stratum basale have?
stem cells that divide and replace shed cells
how many layers does stratum spinosum consist of?
8-10 layers
what does stratum spinosum produce?
keratin fibers
how many layers does stratum granulosum consist of?
2-5
what type of cells does stratum granulosum consist of?
dying, flat cells with keratohyalin granules (lamellar bodies)
what do keratohyaline granules (lamellar bodies) contain?
lipid and keratin fibers
what does stratum lucidum consist of?
several cells that appear glassy and consist of flattened, dead cells filled with keratin
what does stratum corneum contain?
25 or more layers of flat, overlapping, dead cells full of keratin
what happens to the layers of the stratum corneum?
they are gradually shed at the top
what is the main skin pigment?
melanin
what is melanin produced from?
the amino acid, tyrosine
what colors can melanin be?
yellow to red or brown to black
what do melanocytes do?
make melanin, pack it in melanosomes to transfer to neighboring keritanocytes to protect them from UV radiation
what is the differences in skin color due to?
the amount of melanin produced by melaninocytes and the color of the melanin
what happens in light-skinned individuals
UV exposure stimulates the melanin production and produces a tan
what can UV exposure cause?
cancer
where is skin color only located?
epidermis
what is erythema of the skin?
when hemoglobin can make a light-skinned individual reddish when the amount of blood flowing through the skin increases.
what can cause erythema?
an inflammatory response stimulated by infection, sunburn, allergic reactions, insect bites or other causes.
what is carotene?
a yellow pigment and a precursor for vitamin A
how does carotene affect the skin?
it accumulates in the dermis and epidermis and it can affect the skin color in light-skinned individuals
why does carotene turn the skin yellowish?
it’s lipid-soluble and when consumed in large amounts excess accumulates in the stratum corneum and in adipocytes of the dermis and subcutaneous tissue.
what are characteristics of the dermis?
it’s vascular connective tissue and is much thicker than the epidermis
what does the thin, superficial papillary layer of the dermis consist of?
areolar connective tissue
what does the dermal papillae do?
increases the surface area for diffusion
what does the dermal papillae contain?
capillaries and sensory receptors