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
what does the the reticular layer of the dermis consist of?
dense irregular layer with collagen and elastic fibers
what direction do collagen fibers go in, in reticular layer?
predominant directions
what produces cleavage lines?
when the elastic and collagen fibers are oriented more in some directions that in others.
why is it important for health professionals to understand cleavage line directions?
because an incision made parallel to the cleavage line is less likely to gap than an incision made across them.
how should incisions be made in relation to the cleavage line to enable healing more quickly and better?
parallel to it
what does subcutaneous tissue (hypodermis) attach?
the skin to deeper tissues
what does the subcutaneous tissue consist of?
adipose and areolar tissue
what does adipose tissue do in the subcutaneous tissue?
stores energy and provides padding and insulation
what are the main type of cells within the subcutaneous tissue?
fibroblasts, adipocytes and macrophages
what do the accessory structures of the skin include?
hair, nails and skin glands
what are the 2 types of hair found on adults?
1) vellus (unpigmented) (short)
2) terminal (pigmented) (long)
where is the hair shaft and hair root located?
the shaft is exposed and the hair root is deep in the follicle
what is the hair bulb?
the enlarged based of the hair root
what is the hair composed of?
columns of dead, keratinized epidermal cells
what are the 3 layers of a hair
1) medulla (soft keratin)
2) cortex (thicker)
3) cuticle (overlapping cells, both with hard keratin)
what is the hair follicle comprised of?
1) dermal root sheath
2) epidermal root sheath (continuous with the epidermis)
what happens if the epidermis is destroyed?
the epidermal cells of the hair follicle can form a new epithelium
what is at the base of the hair shaft?
a mass of epidermal cells called the matrix
what does the matrix do in the hair shaft?
produces the hair and internal epidermal root sheath
why does the dermis project into the hair bulb?
to form a hair papilla
what is the hair papilla made of?
areolar tissue with capillaries to nourish the matrix
how is hair produced?
in cycles of growth, resting and starting anew.
what happens during a growth stage?
hair increases in length and matrix cells are produced, differentiate, become keratinized and die. it eventually grows longer as cells are added at the base of the hair root
what happens during the resting stage?
hair growth stops, the hair follicle shortens and holds the hair in place.
where are cycles of hair growth longer?
the scalp producing longer hair
what does the length of the growth and resting stage of hair depend on?
the type of hair (eyelashes grow for approx. 30 days and rest for 105 and scalp grow for 3 years and rest for 1-2 years)
what causes hair color?
melanocytes pass melanin to keratinocytes in the matrix
what does a reduction of melanin in the hair cause?
it to become white
what is the arrector pilli made of?
smooth muscle
what can the arrector pilli do?
contract to straighten the hair and pull it up to produce goosebumps
what do sebaceous glands secrete?
sebum into the hair follicle
where do some sebaceous glands open to?
the skin surface
what does sebum do?
1) prevents drying skin
2) conditions hair
3) protects against some bacteria
types of sweat glands
1) eccrine (merocrine) sweat glands
2) apocrince sweat glands
where are eccrine glands found?
all over the body surface
where does eccrine glands open to and what do they release ?
the body surface and release hypotonic fluid
though not very significant what does eccrine glands secrete? (3) (MOW)
1) mostly water with some electrolytes (NaCl)
2) organic nutrients (lactic acid)
3) waste products (ammonia, urea and uric acid)
what method do approcrine glands secrete?
by the merrocrine method
where appocrine glands empty into?
hair follicles in the axillae (arm pits) and genitalia
what does apporcine gland not help with?
keeping the body cool
when do appocrine glands become functional?
at puberty
what are the ear canal ceruminous glands?
modified eccrine sweat glands
what does ceruminous glands secrete?
secretion combined with sebum form cerumen (earwax)
what are mammary glands?
modified apocrine sweat glands
what sweat gland causes body odor?
appocrine glands
how does body odor occur from appocrine glands?
when the organic substancs which are odorless are first released they are quickly metabolized by bacteria that causes the smell.
what does the nails on the digits consist of?
dead cells containing hard keratin
where is the nail body located?
it covers and slides over the nail bed epidermis
where does the nail free edge extend over?
the hyponychium
what is the hyponichium?
a thickened epidermis
how is the cuticle (eponychium) formed?
the skin is pulled by the emerging nail
what is another name for cuticle
eponychium
where does nail growth occur?
at the nail matrix in the nail root
what is the nail matrix and bed composed of?
epithelial tissue with a stratum basale that gives rise to the cells of the nail.
what does the skin provide?
various protections for the body
what are some protections that the skin provides? (6) (PPMHNI)
1) protects underlying structures from mechanical damage
2) prevents microorganisms and other foreign substances from entering the body
3) melanin absorbs UV light and protects skin
4) hair provides protection
5) nails protect end of fingers and toes
6) intact skin plays a role in water loss
how does skin play a role in protections from water loss?
because its lipids act as a barrier to the diffusion of water
what does the cutaneous membrane have?
sensory receptors
what is the skin involved in?
thermoregulation
what does skin produce?
a precursor for vitamin D
how is vitamin D3 made?
1) UV exposure converts a cholesterol derivative to cholcalciferol
2) later cholcalciferol is converted to calcitrol (vit D3)
what does vitamin D3 stimulate?
the uptake of calcium and phosphate in the intestines
what is lost in sweat?
an insignificant amount of some waste products
