1.1 structure and function Flashcards
where am I derived from? (1) epidermis (2) dermis (3) melanocytes
- ectoderm 2. mesoderm 3. neural crest cells
ectoderm (MEAN) - Merkel cell, melanocytes, epidermis, adnexal structure, nerves
mesoderm - langerhan cell, inflamm cells, vessels, fibroblasts
what are the layers of the epidermis
corneum, lucidum (only hands/feet), granular (profilaggrin, cornified envelope), spinosum (ceramide), basale (ornithine decarboxylase)
what are the different types of junctions?
desmosomes - connects epidermis to keratin, includes desmoglien, desmocollin, desmoplakin, plakophilin, plakoglobin, etc
tight junctions - tight seal against water loss in granular layer, includes occludins and claudins
adherens junctions - attaches to actin, includes plakoglobin, beta catenin, alpha catenin
gap junctions - connexons, helps with intercellular communnication
**plakoglobin in adherens and desmosomes
s. granulosum (keratin ___ and _____)
s. spinosum (keratin ___ and _____)
s. basale (keratin ___ and _____)
- keratin 2, 11
- keratin 1,10
- keratin 5, 14
what does ornithine decarboxylase do?
cellular proliferation from basal layer and up; stimulated by various factors including trauma and UV. Inhibited by retinoids, steroids, and vit D
needs CALCIUM??
Where is the cornified cell envelope ?
granular layer
- reinforced by LORICRIN which starts with TRANSGLUTAMINASE 1
**where is the defect? TG1 - lamellar ichthyosis, TG3 - dermatitis herpetiformis
type I keratins (acidic)
type II keratins (basic)
- K9-28, K31-40, chromosome 17
- K1-8, K81-86, chromosome 12
what interleukins do keratinocytes produce?
IL-1/6/8/10/12, TNF alpha (basically a th1 response?)
- what is responsible for the production of melanocytes?
2. the maturation and migration of melanocytes?
- MC1-R, defect responsible for red hair (think increased pheomelanin/eumelanin)
- c-kit, defect a/w piebaldism and mucosal/acral melanoma
what is the difference btw pheomelanin and eumelanin?
pheomelanin (red/yellow), eumelanin (brown/black)
Positive immunostains for langerhan cells?
CD1a, S100, CD207 (**latter is most sensitive and called langerin)
positive immuostain for Merkel cell
CK20+
what is a Merkel cell vs. langerhan cell vs. glomus cell?
Merkel cell - mechanoreceptor of hands, lips, mouth, and hair
langerhan cell - major antigen presenting cell (APC) of the skin
glomus cell - smooth muscle cells which allow for blood shunting from arterioles to venules, seen in hands and feet
the dermis is mainly composed of COLLAGEN
Collagen I (primary collagen), Collagen III (vascular, fetal skin, GI, scars/keloids), Collagen V
dependent on VITAMIN C
**defect in Ehlers danlos (classic EDS defect COL5, vascular EDS COL3, arthrochalasia EDS COL1)
Collagen I/III normal ratio: 5 to 1
Collagen I/III keloid ratio: 20 to 1
what is the dermis composed of (specifically extracellular matrix)?
collagen & elastic fibers surrounded by ground substance (#1 HYALURONIC ACID)
There are 3 different types of adnexal structures (eccrine, apocrine, and sebaceous glands)
eccrine - palms/soles, cholinergic (acetylcholine)
apocrine - genitalia, axillae, lips, external ear, breast, periumbilical region; adrenergic (catecholamine)
sebaceous - face, upper trunk; adrenergic (catecholamine)
ectopic sebaceous glands:
- meibomian glands
- zeis glands
- fordyce spots
- montgomery tubercles
- Tysons glands
- eyelid tarsal plate
- eyelid margin
- lips
- areola, nipple
- labia minora/prepuce
specialized nerve endings:
- Krause end bulbs
- meissner’s corpuscle
- pacinian corpuscle
- merkel nerve ending
- Ruffini corpuscle
- genitalia, perianal region, lips “KRAZY KRAUSE IN EROTIC AREAS”
- light touch of fingers
- vibration
- pressure/touch
- sustained pressure, fingernails
what are the layers of the hair follicle (inner to outer)?
medulla, cortex, inner root sheath (cuticle, huxley, henle), outer root sheath, glassy membrane
phases of hair cycle?
anagen, catagen, telogen, exogen
what are the 3 phases of wound healing?
- inflammatory - < 1 week, platelets/fibrin/neutrophils + MACROPHAGES
- proliferative - < 1 month, keratinocytes/collagen/myofibroblasts
- remodeling - > 1 month, collagen/fibroblast
scar strength @ 1 week, then @ 3 weeks, then @ 3 months, then @ 1 year
5%, 20%, 50%, and 80%
innate vs. adaptive immunity
which cells are involved in each and what is the difference between the 2?
innate - no memory cells, just what you are born with. cannot recognize self-antigens, just foreign antigens. includes dendritic cells, NK cells, phagocytes, and granulocytes
adaptive - relies on memory cells. can recognize self and foreign antigens. includes dendritic cells, B and T cells
which cytokine promotes TH1 pathway? TH2 pathway? TH17 pathway?
- IL12
- IL4
- IL23
TH1 pathway - promotes IL2, IL12, TNF alpha, IFN gamma (e.g. psoriasis, tub leprosy)
TH2 pathway - promotes IL4, IL5, IL6, IL10, IL13 (e.g. atopic derm, lepromatous leprosy)
TH17 pathway - promotes IL6, IL17, IL22, IL 23, IL 36, and TNF alpha
What is the clinical correlation with TLR2 and TLR7
TLR2 is activated by P.acnes and TLR7 is blocked by imiquimod
what are the markers of B cells? T cells? langerhan cells? natural killer cells?
- CD19, CD20
- CD2/3/4/8
- S100, CD207 (langerin), CD1a
- CD56
which is the only Ab that crosses the placenta?
IgG
what is the importance of HBD-2 (human beta defensin), an antimicrobial peptide?
upregulated in psoriasis, downregulated in atopic derm
MHC locus in humans is known as the HLA human leukocyte antigen. What chromosome is it on?
chromosome 6
MHC class I
CD8+ cells
expressed on all nucleated cells
presents antigens from endogenous peptides
MHC class II
CD4+ cells
expressed on APC
endocytosis of extracellular antigens
