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126 Cards in this Set

  • Front
  • Back
Name the 3 layers of skin
epidermis
dermis
hypodermis
Name the 5 layers of the epidermis
stratum basale
stratum spinosum
stratum granulosum
stratum lucidum
stratum corneum
Describe the epithelium of the epidermis
stratified squamous keratinized epithelium
Describe the connective tissues of the dermis
dense irregular connective tissue
Name the two layers of the dermis
papillary layer (upper, loose)
reticular layer (lower, denser)
Characterize the hypodermis
superficial fascia, loose, fatty connective tissue (not part of the skin proper)
Name the 4 major cells of the epidermis
keratinocytes, melanocytes, Langerhans Cells, Merkel Cells
What is the major cell type of the epidermis?
keratinocytes
What defines the different layers of the epidermis?
differentiation of the keratinocytes
Describe the stratum basale as a whole
the point of major cell proliferation
Describe cell communication within the stratum basale
connected to each other through desmosomes and connected to the basement membrane through hemidesmosomes
Describe the cells characteristic of the stratum basale
proliferating keratinocytes and immature post-mitotic cell
Where do cells that are pushed out of the stratum basale go?
to the stratum spinosum
Describe the state of cells in the stratum spinosum
protein synthesizing and preparing for keratinization
Describe the shape of keratinocytes in the stratum spinosum
large, cuboidal or polyhedral
Describe the major protein being synthesized in the keratinocytes in the stratum spinosum
keratins
How does the stratum spinosum get its name?
keratinocytes are connected to each other through desmosomes and due to artifactual shrinkage, they pull apart creating spines
Describe the state of cells within the stratum granulosum
the cells become flattened and storage of products becomes more important
What are keratohyalin granules?
aggregates of profilaggrin (phosphorylated protein needed for keratinization)
How are keratohyalin granules visualized in the light microscope?
deeply staining, lack a membrane
What are lamellar bodies within the stratum granulosum?
membrane-bound vesicles filled with lipid droplets and hydrolytic enzymes
What is the function of lamellar bodies within the stratum granulosum?
integral in forming the water-impermeable layer
What layer does keratinization begin?
stratum lucidum
Describe the thickness of the stratum lucidum and why this is so
Very thin because keratinization is a very rapid progress
What is a keratinized squame?
dead bag of highly cross-linked proteins
What is keratinization?
conversion of keratinocytes to keratinized squames
Describe the composition of the keratinized squame
2 sets of cross-linked proteins: 1 right under the plasma membrane (cornified envelope) and bundled proteins in the center
Describe what happens to the cells organelles when keratinization occurs?
organelles are destroyed
What happens to the lamellar bodies during keratinization?
contents are secreted and lipid droplets coat the plasma membrane making a water-impermeable barrier
what happens to the keratins which have cross-linked to form the cornified envelope?
they aggregate and become cross-linked by transglutaminase
Describe the state of the stratum corneum
consists of cornified squames connected to each other through desmosomes and embedded in a lipid layer
What determines the thickness of stratum corneum
the rate of squame production and the rate at which the cells slough off
What is ichthyoses
perturbations in the rate at which squames develop and get sloughed off
What do melanocytes secrete?
melanosomes (which contain melanin)
What results due to melanosome synthesis impairment?
albinism
Describe the synthesis of melanin within the melanosome
tyrosine is transported into melanosome vesicle, tyrosinase turns it into activated precursor which will form melanin
Describe the intermediate step in melanin formation
melanosomes are transported to the ends of the dendritic processes.
Describe the final step in melanin formation
Melanosome are secreted in an apocrine fashion, they are phagocytosed and taken to keratinocyte lysosomes, and melanin is the only part resistent to degradation.
What is the main location of melanocytes?
Mainly in the stratum basale with processes extending into the stratum spinosum
What do melanocytes derive from?
neural crest cells
What is the function of Langerhans cells
antigen-presenting cells
How do the Langerhans cells accomplish their function?
They accumulate antigens in the epidermis and travel to the lymph nodes where they present the antigen to the lymphocytes
Describe the location of langerhans cells
located within the nucleated layers of the epidermis (mainly the stratum spinosum)
How can Langerhans cells be differentiated in the microscope?
long processes extending between keratinocytes, light staining cytoplasm, indented nucleus
Describe the originof the Langerhans Cells
derived from the bone marrow much like the rest of the blood cells (probably similar lineage as monocytes)
What is the function of the merkel cell?
mechanoreceptors
How do mechanoreceptors accomplish their function?
contained dense-cored granules and make synaptse-like connection to sensory nerve fibers
Describe the location of Merkel cells
Located within the stratum basale particularly at areas of enhanced tactile perception
How can Merkel cells be differentiated from keratinocytes?
they can't without special stains
What are dermal papillae?
finger-like projections of the dermis that project into the epidermis
What are rete ridges?
the corresponding ridges of the epidermis that match up to the dermal papillae
Where is the dermal papillae/rete ridges most noticeable?
in areas that aren't hairy
Describe the significance of the basal lamina of the epidermis
it's typical, however autoimmune reactions to hemidesmosomes or basement membrane components results in blistering diseases
Describe the papillary layer
looser connective tissue, adjacent to the epidermis
Describe the reticular layer of the dermis
denser connective tissue, adjacent to the hypodermis
Describe the cells of the dermis
typical of connective tissue
Where are the 2 main plexuses of blood vessels within the dermis located?
between papillary and reticular layer and between cutaneous and subcutaneous layers
In addition to the 2 venous/arterial plexuses, there is an addition 3rd plexus consisting solely of veins. Where is this located?
within the reticular layer
Describe the blood supply to the dermal papillae
capillary loops follow the ridges (results in a pink color in the skin)
Describe how thermoregulation is accomplished within the dermis
arteriovenous anastomoses can shunt blood away in order to retain heat or it can engorge to allow the dissipation of heat.
Describe the lymphatic organization of the dermis
lymphatic vessels loop up into the dermal papillae and drain into one of two plexuses
Where are the plexi located in the dermis?
between the reticular and papillary layer and between the cutaneous and subcutaneous layers
What two types of nerve endings do sensory nerves give rise to?
free nerve endings and encapsulated nerve endings
Where do free nerve ending terminate within the skin?
in the dermis and epidermis
Where can Meissner's corpuscles be located in the skin?
in the dermal papillae
What is the pilosebaceous unit?
the hair follicle, glands, and arrector pili muscle complex
Describe the structure of the hair follicle
tubular invagination of the epidermis
What is the lining of the hair follicle called?
the outer root sheath
Where is the hair bulb located in the hair follicle?
at the base
Name the cells of the hair bulb
keratinocytes and melanocytes
What forms the inner root sheath?
concentric layers formed by keratinocyte proliferation
What forms the hair shaft?
concentric layers formed by keratinocyte proliferation
What induces the development of the hair bulb?
the dermal papillae at the base of the outer root sheath
What does the dermal papillae of the hair bulb do to induce growth at the hair bulb?
provides blood flow through the capillary loop
Name the 2 types of dermal papillae in the skin
dermal papillae of the dermo-epidermal junction and dermal papillae of the hair bulb
If you were to look at a cross-section view of the hair follicle, name the layers from the outside in
outer root sheath
inner root sheat
hair shaft
Describe the orientation of the outer root sheath in comparison to the hair follicle
at a 90 degree angle
What about the outer root sheath differs from the inner root sheath and hair follicle
derives from the epidermis, not the hair bulb
How is the inner root sheath different from the hair shaft?
it does not extend above the skin
What happens to cells of the inner root sheath at the skin cell surface?
they are sloughed off with the sebaceous gland secretion
Describe the hair shaft
consists of 2 to 3 layers, depending on the type of hair
How is keratinization of the hair follicle keratinocytes different from that of the epidermis?
1) different keratins are involved
2) cornified squames are not desquamated
Name the 3 phases of the hair growth
anagen
catagen
telogen
What is the status of hair growth in anagen?
period of active growth
What is happening to the hair bulb during anagen?
hair bulb reforms and migrates deeper into the skin forming the inferior portion of the hair follicle
What is the status of hair growth in catagen?
regression
What is happening to the hair bulb during catagen?
bulb moves away from the dermal papillae and toward the surface of the skin
What is the status of hair growth in telogen?
resting, non-growing
What is happening ot the hair bulb during telogen
proximal end of the hair shaft is the keratinized remnant of the hair bulb. Hair is shed upon the beginning a new growth cycle
What is the origin/insertion of the arrector pili muscle?
attaches to the basement membrane of the epidermis adn the hair follicle
What happens when the arrector pili muscle contracts?
increases the angle between the hair follicle and the surface of the skin
What innervates the arrector pili muscle?
sympathetic nervous system (think of when the cat gets scared)
Describe the sebaceous glands of the hair follicle
simple alveolar
Where are sebaceous glands located in reference to the hair follicle
near the superficial aspect
What is the function of sebaceous glands?
to secrete lipids into the hair shaft and the surface of the skin
What regulates the development of the sebaceous glands?
sex steroids
What is the cause of acne vulgaris?
inflammation of the sebaceous glands
What method do sebaceous glands use to secrete their fluid?
holocrine secretion
Describe the process of developing secretory material in the sebaceous gland
immature cells near the basal lamina, they mature and get pushed out where they accumulate lipid droplets, then they move to the end of the gland where they undergo apoptosis and the material is dumped into the space
Describe the pattern of size of the sebaceous glands
vary depending on region
What are the 2 major sweat glands of the integument system
apocrine and eccrine
What is the shape of the sweat glands of the integument system
simple unbranched coiled tubular
Where are eccrine sweat glands located?
throughout the body (not with the hair follicles)
What is the major function of eccrine sweat glands
thermoregulation
Where are apocrine glands typically found?
within the pilosebaceous unit in the anogenital region, axillae, and areola
Describe the development of apocrine sweat glands
become active around puberty
Name the epithelium of the excretory ducts of the eccrine and apocrine sweat glands
stratified cuboidal
What is a specialized cell located within both the eccrine and apocrine epithelium?
myoepithelial cells
How do eccrine and apocrine sweat glands differ?
based on their secretion and the types of secretory cells
Classify mammary sweat glands
modified apocrine sweat glands
How do mammary glands receive their blood supply?
from the surrounding skin
Describe the support tissue of the parenchyma cells of the mammary gland
adipose tissue of the hypodermis
When do the mammary glands become active? What causes this?
Like apocrine glands, they become active at puberty due to the influence of sex steroids
How are mammary glands similar to apocrine glands
same secretory cells, same structure of acini and duct system, both contain myoepithelial cells
Describe the type of secretion used by the mammary gland
holocrine for proteins, apocrine for lipids
How does secretion of mammary gland product occur?
secretory endpiece continuously synthesize product and it backs up into the lumen. Myoepithelial cells contract and propel product out of the duct
What causes the myoepithelial cells to contract?
oxytocin from the posterior pituitary
Describe the lobular composition of the mammary gland
composed of 15-20 lobes which all open into the nipple
What is the lactiferous duct?
the main duct in the mammary gland
What is the epithelium of the lactiferous duct?
stratified squamous
What is the lactiferous sinus?
the slight dilation just prior to the opening of the lactiferous duct
Describe the epithelium of ducts feeding into the lactiferous sinuses
stratified cuboidal
Where are myoepithelial ducts found in the mammary gland?
in the epithelium between epithelial duct cells in the basal lamina
What changes occur in the mammary gland due to pregnancy?
terminal parts of the lactiferous ducts develope secretory acini
When does secretion of the secretory acinus product begin in the mammary gland?
after parturition
What changes does the mammary gland undergo upon weaning?
secretory acinus undergoes apoptosis and become phagocytosed