2/3/16 - Exam 3 Flashcards
Fitzpatrick Skin Types
I-VI, check if need to know specifics
Eumelanin
black to brown pigment
Pheomelanin
yellow to red-brown pigment
Langerhans cells
epidermally located, implicated in immune function
• Found in small numbers in all of the epidermal layers
• Dendritic cells in the epidermis derived from a bone marrow stem cell
• Participate in cell-mediated immune reactions by processing and presenting antigens (circulate
back and forth between skin and lymph nodes)
Keratinocytes do what -
Vitamin D synthesis, Water homeostasis (w/ Adnexa: Eccrine glands)
Adnexa: Eccrine glands do what -
Water homeostasis (w/ keratinocytes) and thermoregulation (w/ blood vessels). These are the sweat glands as opposed to the sebaceous glands
Dermis is -
an underlying connective tissue layer, which includes:
• the papillary layer (loose connective tissue) lies immediately under the epidermis
• a deeper reticular layer (dense connective tissue)
Vitamin D Synthesis
- 7-dehydrocholesterol can be converted to cholecalciferol (Vitamin D3) in the skin by
UVB - Cholecalciferol (Vitamin D3) and Ergocalciferol (Vitamin D2) can both be ingested
and absorbed through the intestines - Vitamin D2 and Vitamin D3 are then converted to calcidiol (25-hydroxy Vitamin D)
by the liver - 1,25-dihydroxy-Vitamin D (calcitriol) is the active form and is synthesized by the
kidneys
Hemidesmosomes are part of what and do what
Important in basal cell layer; attach basal cells are firmly to the basal lamina of the dermal epidermal junction
• Antibodies to proteins in the hemidesmosomes may cause autoimmune blistering diseases such as bullous pemphigoid
• Genetic defects in Collagen VII cause Dystrophic Epidermolysis Bullosa
• Genetic defects in Laminin-5 cause Junctional EB
Desmosomes funtion in the basal membrane is to
Attach keratinocytes to each other;
Antibodies to proteins in the desmosomes may cause autoimmune blistering diseases such as pemphigus vulgaris
Congenital defects in Keratin filaments 5 and 14 cause Epidermolysis bullosa simplex
Tonofilaments: protein structures (keratin filaments) that insert into the dense plaques of desmosomes on the cytoplasmic side of the plasma membrane
stratum spinosum
• Has a “prickly” or spiny appearance due to desmosome attachments between cells
• intercellular adhesion depends upon the tonofilament-desmosome interaction in the
distribution of stress
• synthesis of involucrin and membrane coating granules begins in this layer
stratum granulosum
• the cells of this layer contain different types of granules
• Keratohyalin granules contain Profilaggrin (filaggrin precursor). Filaggrin cross-links
keratin tonofilaments and is important in the barrier function of the skin. Filaggrin is
mutated in dry skin conditions including ichthyosis and atopic dermatitis.
stratum lucidum
- under the light microscope, a thin, light staining band seen only in thick skin
- cells of this layer no longer have nuclei or organelles
stratum corneum
- the outermost layers of epidermis
- keratinocytes have lost their nuclei and organelles and the entire cell is filled with keratin • desmosomes still connect tightly packed adjacent cells
Papillary Layer (of dermis)
- site of attachment to epidermis and necessary to its development and differentiation • contains capillary network that is blood supply for epidermis
- pathway for defense cells
- contains Meissner’s corpuscles which sense touch
Reticular Layer
• contains extensive collagen and elastic fibers that provide strength and flexibility
• houses (along with hypodermis) epidermal derivatives such as glands and hairs and plays a major
role in their development and functioning
• pathway for major blood vessels arranged specifically to facilitate thermoregulation • site of nerve tracts and major sensory receptors
• Pacinian corpuscles sense vibration, pressure and touch

Meissner’s corpuscles
- detect delicate touch
- are most commonly found in the dermal papillae of thick skin
- consist of Schwann cells and sensory nerve terminals wrapped by fibroblasts and collagen
Pacinian corpuscles
-are rapidly adapting receptors that detect changes in deep pressure (vibrations)
-are found in the dermis of both thin and thick skin
-large structures resembling an onion
-the concentric layers are composed of flattened connective tissue-like cells interspersed with
intercellular fluid and collagen
-a single sensory nerve fibers terminates within this structure
Apocrine sweat glands
-Specialized sweat glands located in the axillary, pubic and perianal regions
-produce a milky, viscid, carbohydrate-rich secretion that is initially odorless; subsequent bacterial
action leads to a characteristic axillary body odor
-begin to function in puberty
-have ducts which empty into hair follicles just above sebaceous glands
Eccrine sweat glands
- Traditional sweat glands distributed over most of the body
- Not found in the lips, under the nails or on the glans penis, glans clitoris, or labia minora
- Watery, enzyme-rich secretion, initially isotonic, becomes hypotonic as Na+ is reabsorbed by the ducts
- Important for thermoregulation
Sebaceous glands
- Oil glands which secrete sebum, a complex mixture of lipids
- develop along with hair follicles and empty their secretion into the upper one-third of hair follicles
- development accelerated at puberty
Where are Meissner’s and Pacinian corp?
MP’s are important for PR - meins in papillary and pacinian in reticular
The “factory” of the dermis that produces collagen fibers, elastic fibers and ground substance is -
fibroblast
Which collagen subtype is associated with the basement membrane?
Collagen IV
A CD34+ cell is a ….
hematopoetic stem cell
Sucquet-Hoyer canal
smooth muscle derived valve-like structure, blood may be directed toward the skin during overheating, or away from the skin in hypothermia
intracellular adhesion molecules (ICAMs)
Modulation of inflammation/leukocyte trafficking – via the expression of intracellular adhesion molecules (ICAMs) white blood cells begin the process of first adherence and rolling, and second diapedesis, so that they may exit the vasculature to fight infection in the skin and soft tissue
Auspitz sign
Seen in psoriasis, occurs when hardened skin forcefully removed because suprapapillary plate is exposed and capillaries bleed as “pinpoints”
Verrucas
benign, virally induced neoplasms (growth) that require an increased blood supply simply to support the virally-proliferating cells. Typified by brownish capillary structures in the center of them
CD16 is expressed on
immature neutrophils, a sign of neutropenia
leukocytoclastic vasculitis
common disease involving the post-capillary venules, due to the precipitation of immune complexes in the walls of vessels - pressure to skin does not make redness go away because redness due to RBC’s in the tissue space
Pruritus (itch)
originates in free nerve endings near the dermoepidermal junction and is conducted centripetally by afferent nerves entering the spinal cord via the dorsal roots. These afferent nerves for pruritus are small, unmyelinated C fibers with a slow conduction rate.
What does a Pacinian corp look like under a microscope?
Onion
Define the “thirds” of a hair follicle
infundibulum representing the upper third, the isthmus being the middle third (from the sebaceous duct to the insertion of the arrector pili), and the matrical area representing the lower third.
finasteride
a 5-α-reductase inhibitor, which block conversion of testosterone to 5-dihydrotestosterone, are used in the treatment of male pattern baldness
What triggers sweating?
Sympathetic autonomic system but more specifically - acetylcholine secretion; important when considering drug effects
Apocrine glands
located only in the axillary and anogenital area. Although present at birth, they remain small and nonfunctional until after puberty
chromohidrosis
Colored sweat, apocrine gland dysfunction
Apoeccrine glands
In axilla, respond to choline stimulus, 10x amount of sweat as eccrine glands
hyperhidrosis
excessive sweating, involves either eccrine glands or apoaccrine glands - botox can be used to treat
