Andrews Flashcards
What are langers lines?
Also known as cleavage lines. Correspond to natural orientation of collagen fibers in dermis. Are perpendicular to orientation of underlying muscle fibers. Used to obtain most cosmetically appealing surgical scar-surgeon cuts in direction of Langers lines.
What are lines of
Blaschko?
They are skin lines invisible under normal conditions. They follow a V shape over the back, S shape over chest, stomach, sides, and wavy shape over head. Believed to trace migration of embryonic cells (epidermal cell migration)
What diseases are associated with the lines of Blaschko?
X-linked dominant-incontinenti pigmenti, CHILD syndrome, focal dermal hypo plasma, MLS syndrome
Inflammatory linear verrucous epidermal naevus, sebaceous naevus, hypomelanosis of Ito, McCune Albright Syndrome, segmental vitiligo
Linear lichen planus, linear cutaneous LE, lichen striatus, linear morphed
What diseases are associated with lines of cleavage?
PR, ashy dermatosis, MF, stage 2 syphilis, lesser trelat syndrome, exam thematic kaposi sarcoma
What is the meaning of centrifugal spread?
Moving outward from center
Meaning of centripedal spread?
Moving toward center of body
What is the average thickness of epidermis?
O.5mm
What types of collagen are present in the dermis?
Types 1,3,5
What type of sweat gland is attached to the pilosebaceous unit?
Aprocrine glands-coiled duct and straight duct
What type of sweat gland empties onto skin surface?
Eccrine gland; Has coiled duct followed by straight duct followed by spiral duct then acrosyringium
What are the four cell types in the epidermis?
Keratinocytes, melanocytes , Langerhans cells, Merkel cell
Describe the Langerhans cell
A dendritic cell of the skin and mucosa containing large granules called birbeck granules. They are scattered throughout the epidermis but are often seen in the stratum spinousum
Markers: CD1a***** S100, langerin
Secrete IL12**-this stimulates growth of T cells
What happens to the basal cells as they migrate upward towards the epidermis
Plasma membrane is replaced with cornfied cell envelope. They flatten and lose nuclei. Extrude cellular contents except for keratin and filaggrin (binds to keratin fibers in epithelial cells; become apart of lipid envelope in stratum corneum, thus playing a role in skin barrier function- blocks UVR and hydrates SC). Filaggrin will also release free amino acids in SC to assist in water retention.
Mutations in filaggrin are associated with what?
Ichthyosis vulgaris. Eczema
Where are the stem cell rich sites located in the epidermis
Rete ridges and hair bulge
Describe keratins
They make up type 1 and type 2 intermediate filaments, 30 different types, they are paired ( acidic and basic)
Type 1: acidic, K9-20, chromosome 17
Type 2: basic, K1-8, chromosome 12
What keratins are associated with basal layer?
5 & 14.
What keratins are supra basilar?
1&10.
What are keratohyaline granules?
In granular layer. Contain pro filaggrin, keratin and loricrin- hydrophobic protein making up most of CCE
What does filaggrin degrade into?
Urocanic acid & pyrrolidone carboxylic acid
What immune factors do keratinocytes secrete?
IL 1. IL 8. TGF B
Express ICAM 1-intercellular adhesion molecule MHC class 2
What are lamellar granules?
Located between granular layer and cornified layer
Contains glycoproteins, glycolipids, free sterols, glucosylceramides.
Plays role in skin cohesion and impermeability. Forms hydrophobic barrier.
Ratio of kcytes to melanocytes?
1: 5 in section
1: 36 in 3d
These are in sun protected skin
Growth and inhibitory factors for melanocytes?
Growth is TGF alpha
Inhibitory is IL 1 IL 6. TGF beta
What enzyme catalyzes melanosome production?
Tyrosinase. Is a copper containing enzyme
Tyrosine–>dopa–>dopaquinone
What are the two forms of melanin?
Eumelanin and pheomelanin
Melanocortin I is most important in regulation of melanin production
Redheads have mutated MCRI
BM thickness?
O.5-1mm
Signaling pathway for development of dermis?
WNT/beta catenin
What are the main components of the dermis?
Ground substance ( mucopolysaccharides) , sub papillary vascular plexus, deeper vascular plexus, fibroblasts, macrophages, mast cells, afferent nerves (meissner and Pacini)
Describe collagen
3 alpha polypeptide chains. Glycine, hydroxyproline, proline, hydroxylysine make it up. Folded in triple helix.
Collagen hydroxylation- prolyl and lysyl hydroxylase. These require vit C
Cross linking of collagen molecules is done by lysyl oxidase.
Stimulators of collagen?
Ascorbic acid, TGF beta, retinoic acid
Inhibitors of collagen production.?
IL 1. Glucocorticoid. Interferon gamma. TNFalpha. Minoxidil Dpenicillamine
What unique amino acids make up elastin?
Desmosine. Isodesmosine.
Elastic fibers are made of?
Microfibrils and elastin
Describe microfibrils
Made of oxytalin that runs perpendicular. Insert into BM from papillary dermis. Are finer
Élaunin fibers run parallel in reticular dermis. Are courser.
What is the dermis extrafibrillar matrix (ground substance) made of?
Glycosaminoglycans (Sugars; negatively charged; bind Ions and water; ex: hyaluronic acid)
Proteoglycans (proteins with attached GAGs. Ex- versican ( forms complex with hyaluronic acid) and Perlecan (BM)
Describe macrophages in the Dermis.
Phagocytic. Microbiocidal. Secretory. Wound healing. Antigen presenting
Express S100, factor 13a, CD 68, 163, 25
Describe dermal dendritic cells
APC. Phagocytic. 2 types- factor 13a (dermatofibroma). CD34
Describe dermal mast cells
Fried egg. histamine. Tissue edema. Ckit gain or loss of function
In the dermis what are glomus cells?
Vascular smooth muscle cells on the palms and soles and digits. Allows for rapid shunting of blood from the arterioles to venules by bypassing capillaries.
Eccrine sweat glands are intervated by what?
Cholinergic
What do the post ganglionic adrenergic fibers innervate?
Arrector pili. Apocrine secretion
What two molecules are found in the subcutaneous fat?
Aromatase. Leptin.
At what gestation do the adnexal structures form?
18-24 weeks
Hair sebaceous eccrine apocrine
Have sushi every afternoon
What are the three sections of the eccrine unit
Describe details of gland!
Intraepidermal spiral duct-acrosyringium. Straight dermal portion. Coiled secretory portion-in the fat
Found almost everywhere
Excrete heavy metals , thermoregulation, source of re epithelialization
Cholinergic innervation
Merocrine secretion (exocytosis from vesicles Gland is not damaged)
Describe apocrine gland
Coiled secretory gland at dermis and subq fat
Excretory straight portion.
Decapitation secretion
Sweat is odorless until it reaches the surface
