Dermal Structures and Diseases Flashcards
Blood vessels, nerves, and cutaneous appendages are found in what layer of the skin?
Dermis
What is the thickness of the dermis?
1-4mm
True or False: The epidermis contains blood vessels.
False
What composes the dermal matrix?
Collagen fibers, elastic fibers and ground substances.
What synthesizes the dermal matrix?
Dermal Fibroblasts
What are epidermal retes?
Downward projections of epidermis
What are dermal papillae?
Upward projections of dermis
What are the functions of epidermal retes and dermal papillae?
They increase the strength of adherence of the epidermis to the dermis and increase surface area.
What does the interlocking epidermal rete and dermal papillae create?
Fingerprints
What is the function of collagen in the dermis?
It provides tensile strength to the skin
Which form of collagen comprises more than 85% of the weight of the dermis?
Collagen I
What form of collagen comprises a large part of the fetal dermis?
Collagen III
What form of collagen is found in high concentration in the “basement membrane zone” and is also prominent around the vessels?
Collagen IV
What type of collagen functions to attach the epidermis to the dermis?
Collagen VII
Procollagen is synthesized intracellularly within what type of cell?
Fibroblast.
Procollagen is comprised of three separate chains of proteins arranged in an alpha- helical. What three proteins form this structure?
Gly-X-Y
glycine)-(proline)-(hydroxyproline
Where are the collagen fibrils assembled? Intracellularly or extracellularly?
Extracellularly
A 72yo retired engineer alcohol male who lives alone is admitted to the hospital for evaluation of wounds on limbs that are not healing well. Multiple ecchymoses are located on his posterior thigh and anterior arm. His skin reveals miinute hemorrhages around hair follicles and splinter hemorrhages around nail beds. His hemoglobin is 9 (normal is 14-18g/dL). What is this patient most likely suffering from?
Scurvy
Scurvy is an acquired abnormality in collagen production as a result of what kind of deficiency?
Vitamin C
Ehlers-Danlos syndrome (EDS) is a congenital abnormality that caused by a disruption in what process?
Collagen synthesis.
What are four clinical characteristics shared by all subtypes of Ehlers-Danlos syndrome (EDS)?
- Skin hyperextensibility (COLLAGEN DEFECT)
- Joint hypermobility
- Tissue fragility
- Poor wound healing
What is the function of elastic fibers?
Resiliency
Collagen fibers stain pink with eosinophilic, what stain is used visualize elastic fibers?
Silver stain (argyrophilic)
Name an example of an acquired disorder of elastic fibers.
Solar elastosis.
What is solar elastosis? Is it acquired or hereditary?
Degeneration of the elastic fibers upon exposure to sunlight. It is an acquired disorder
How can you diagnose solar elastosis?
Normal elastic fibers stain silver while sun damaged elastin stain blue (basophilic)
Name an inherited form of elastic disorders.
Pseudoxanthoma elasticum (PXE)
What gene is effected by pseudoxanthoma elasticum?
The gene encoding for the part of the “multidrug resistance complex”. Elastic fibers become enlarged, tangled, and calcified and stain a purple-blue color.
What are some symptoms about PXE?
Hypertension, bleeding disorders, and “plucked chicken” neck.
What two glycosaminoglycans primarily make up ground substance?
- Hyaluronic Acid
2. Dermatan Sulphate
What is the function of ground substance?
Provide nutrients to epidermis
Name three functions of the cutaneous vascular system.
- Wound Healing
- Control of homeostasis
- Modulation of inflammation/leukocyte
Leukocytoclastic vasculitis is an example of what type of immune response?
Type III. Immune complexes (usually due to Strep infection) in post-capillary venules. Resulting in palpable purpura
Describe the location, function and types of nerves associated with free nerve endings
Location: Dermoepidermal Junction
Function: Pain and Itch sensation
Nerves: Afferent unmyelinated C fibers with slow conduction
What is the function of Pacinian corpuscles?
Sensing pressure and vibratory areas
What is the function of Meissner’s corpuscles?
Fine touch and tactile discrimination
What type of nervous tissue is concentrated in the distal aspects of the digits?
Meissner’s corpuscles
What disorder is caused by mutations in the neurotrophic tyrosine receptor kinase 1 (NTRK1) gene?
Congenital insensitivity to pain usually co-existing anhidrosis
Name two types of hair and where are they located?
- Terminal Hairs- Scalp, beard, pubic hair
2. Vellus Hair- Diffusely in the body
What smooth muscle raises hair?
Arrector pili
Name the three subdivisions of hair.
Infundibulum- upper 1/3
Isthmus- middle 1/3
matrical area- lower 1/3
The follicular unite is dervived from what primitive structure?
The primitive ectodermal germ (PEG)
What parts (bulges) of the PEG are significant and what do they lead to?
Lower bulge- attachment for arrector pili
Middle bulge-sebaceous gland
Upper bulge-apocrine gland
Define anagen.
The growth phase of hair
Define telogen.
The resting phase of hair
Define catagen.
The transition phase between the anagen and telogen phase
What is used to treat male pattern balding?
finasteride, a 5-alpha-reductase inhibitor
What is the action of minoxidil?
it is a drug that promotes the anagen phase of hair growth.
Sebaceous glands are what a classic example of what type of gland?
Holocrine
What drug can be used to decrease sebum production?
Isotretinoin (Accutane)
What bacteria is associated with acne?
Propinonibacterium
What is the function of eccrine glands?
Thermoregulation
Sweating is mediated by the sympathetic portion of the autonomic nervous system and is triggered by what secretion?
Acetylcholine
Where are apocrine glands located?
Axillary and anogenital area
Name three types of apocrine glands.
Moll’s glands on the eyelids, cerumen (ear wax), and lactation glands
What is chromohidrosis?
A disorder of the apocrine gland. Lipofuscin pigment colors secretions yellow, green, blue, or black.
Botox can be used to treat excessive sweating because it blocks the release of what?
Acetylcholine
