Integumentary System Flashcards
blood flow through the skin is adjusted via _____
arteriovenous shunts
integumentary system makes Vitamin ___ in response to UV radiation in sunlight, which plays an important role in ___
Vitamin D - calcium regulating hormone
hypodermis =
superficial fascia - contains blood vessels and nerves supplying the dermis, sweat glands, ends of hair follicles, adipose
proliferating fibroblasts and blood vessels for wound repair come from hypodermis
proliferating fibroblasts and blood vessels for wound repair of integumentary system come from
hypodermis (aka superficial fascia)
thick skin is sometimes called
glabrous skin - has sweat glands but not hair/related structures
differences in the thickness of thin skin are based on ___
thickness of the dermis
as keratinocytes migrate to the surface of skin, they die and become
corneocytes (squames of keratin)
replaced every ~28 days
what are the layers of the epidermis (beginning top to dermis)
- (top) stratum corneum
- stratum lucideum
- stratum granulosum
- stratum spinosum
- stratum germinativum (basale)
(then dermis)
the proliferative/germinal layer of the epidermis:
stratum germinativum (basale, directly above dermis): 1-2 cells thick
one undifferentiated stem cell in this layer can produce whole epidermis
“prickle cell” layer of epidermis (cells appear to have spines)
stratum spinosum (second deepest, superficial to stratum basale) - very prominent desmosomes with keratin (intermediate filament) for mechanical strength (“spines”)
*friction blisters occur here if desmosomes are disrupted and fluid collects between keratinocytes
where can lamellar or membrane coating granules be seen in the epidermis? what do the granules contain?
stratum spinosum (2nd most deep layer after stratum basale)
granules contain glycolipids and sterols that make skin waterproof
where can keratohyalin granules (stain dark blue) be found in the epidermis
stratum granulosum (3rd layer)
keratohyalin granules: dense, irregular, no membrane, contain tonofilaments (keratin intermediate filaments)
fill the cell and become polymerized in final keratin product (squame of keratin at skin surface)
this layer of epidermis has 15-20 layers of flattened dead corenocytes (squames)
stratum corneum (layer 2 from top): major barrier to water loss and penetration
keratohyalin granules + tonofilaments (keratin) become amorphous and cross-link with filaggrin —> flattens cells
half the thickness of thick skin
no nucleus or organelles evident, just keratin coated with lipids released from lamellar granules (from stratum spinosum)
dermatoglyphics
aka fingerprints
each ridge of epidermis is a fingerprint and each epidermal ridge covers a dermal ridge
dermal ridge is subdivided by an interpapillary peg of epidermis to form 2 dermal papillae
interpapillary peg is where ducts of eccrine sweat glands enter. epidermis
in thin skin, the stratum ____ is only a few cells thick and is often detached from lower layers during preparation of slides
stratum corneum
transdermal medications work by…
traversing the skin layers via the lipids between cells to reach blood vessels in dermis
Rhus dermatitis
aka poison ivy/oak/sumac
urushiol causes contact dermatitis (found in all parts of plant)
treatment requires immediate washing or OTC itch relief later
melanocytes are found mostly in [thin/thick] skin and are derived from the ____
melanocytes found mostly in thin skin, derived from neural crest
cell bodies found in stratum germinativum (basale) but have dendrites that reach up
melanin production requires this enzyme
tyrosinase: converts tyrosine to melanin
melanin is produced in melanosome, pinched off, and distributed
individuals with dark skin produce:
a. more melanocytes
b. more pigment
b. more pigment (but same number of cells) - degraded more slowly and distributed further
other than protecting DNA of stem cells, melanin also protects ____ in capillaries
folate (form of Vitamin B)
melanosomes are degraded by _____ in keratinocytes
lysosomes
this disease is caused by a defect in the transport of melanosomes, due to mutation in either myosin Va, Rab27a, or melanophillin (Rab effector). What is?
Griscelli syndrome
Langerhans cells are a special form of DC that are derived from ____
monocyte/macrophage line
proceses form a continuous layer in the stratum basale and spinosum of both thick and thin skin
Langerhans cells and their processes form a continuous layer in the stratum ____ and ____
germinativum (basale) and spinosum
Langerhans cells contain tennis-racket shaped _____ granules that….
Birbeck granules: function in uptake of microbial fragments
____ glands are associated with hair follicles
sebaceous glands are associated with hair follicles
hair ___ is the area of growth at the base of the hair
in the ______ zone, cellular hair is transformed to keratin over time
hair matrix - where cells proliferate and manufacture keratin (in hair bulb, surrounded by dermal papillae)
keratogenous zone - cellular hair transformed to keratin
(hair is made of a mixture of keratins)
sebaceous glands produce ___ via ____ secretion
sebum: oil that keeps hair soft and waterproof
holocrine secretion: sebaceous glands die and liberate contents into hair follicle
stem cells at periphery of gland, oldest in the center
smooth muscle innervated by sympathetic ANS that induces piloerection of hair
arrector pili muscles - found on same side of hair follicle as sebaceous gland
what are the 2 types of sweat glands?
- eccrine: tubular glands with coiled secretory portion (dermis or hypodermis), glands are stratified cuboidal - temperature regulation, hypotonic sweat (more water lost), NOT associated with hair follicles
- apocrine: axilla, areola, pubic - secrete sweat after puberty, hormone sensitive, have large lumen (simple columnar), usually associated with hair follicles
tubular sweat glands with coiled secretory portion, functioning in temperature regulation and secretion of hypotonic sweat (more water lost)
what are?
eccrine sweat glands
these sweat glands have a large lumen, are found in axilla, areola, pubic, and secretions are hormone regulated. what are?
apocrine sweat glands - usually associated with hair follicle
what kind of epithelium lines eccrine vs apocrine sweat glands?
eccrine: very small lumen, stratified cuboidal (temperature regulation)
apocrine: very large lumen, simple columnar (hormone-mediated secretion)
specialized smooth muscle cells with clasp sweat and other glands in skin with long cytoplasmic processes
myoepithelial cells - when stimulated by ANS they contract and expel sweat quickly
also found in mammary glands (sensitive to oxytocin) and salivary glands (respond to food cues)
what is the benefit of the many dermal papillae and interpapillary pegs in thick skin?
provides greater surface area for diffusion and mechanical attachment at epidermal-dermis junction
what are the 2 layers of the dermis
- papillary layer: rich in capillaries to nourish avascular epidermis, elastic fibers
- reticular layer: more fibrous, collagen bundles oriented in lines of tension (Langer’s line)
*wounds parallel to these lines heal with little scarring, those cutting across leave noticeable scars
light touch receptors in the skin, found in papillary layer of dermis
what are?
Meissner’s corpuscles
large encapsulated nerve endings found deep in the dermis or hypodermis, which function as pressure receptors
Pacinian corpuscles (look like onions)
Meissner vs Pacinian corpuscles
Meissner: light touch mechanoreceptors, papillary layer of dermis
Pacinian: encapsulated nerve endings, pressure receptors, deep in dermis or hypodermis, look like layers of onion (remember Pacinian is for Pressure)
you’re looking at a histology slide of skin when you notice a structure that looks like an onion deep in the dermis, almost in the hypodermis. what is it most likely to be?
Pacinian corpuscles - pressure receptor, large encapsulated nerve ending
*note these are also found in internal organs such as pancreas
Meissner’s corpuscles
light touch mechanoreceptors in the skin, found in papillary layer of dermis
these mechanoreceptors are located at the tips of primary epidermal ridges and are connected to receptors in the dermis
they are sensitive to points, edges, and texture. what are?
Merkel cells
Merkel cells
found at tips of primary epidermal ridges
sensitive to points, edges, and texture
_____ are oriented parallel to collagen bundles in the dermis and are sensitive to stretch
Ruffini endings
Ruffini endings
parallel to collagen bundles in the dermis, sensitive to stretch
what structures of the skin will respond to the following sensations:
a. light touch
b. pressure
c. points, edges, texture
d. stretch
a. Meissner’s corpuscles - light touch
b. Pacinian corpuscles - pressure
c. Merkel cells - points, edges, texture
d. Ruffini endings - stretch
