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
