Gross Anatomy: The Skin

7/21/2019 Gross Anatomy: The Skin

http://slidepdf.com/reader/full/gross-anatomy-the-skin 1/5

SKIN

Functions1. Protection2. Sensation3. Homeostasis

ThermoregulationFluid electrolyte balance

4. Secretion5. Immunologic Surveillance

Layers of the SkinEpidermis-paper-thin like layer

11once they reach the s. corneum, they are actually already anucleate and they desquamate or are shed off

12each layer is named after a feature or somethingbasale -> basal

germinativum -> mitoticstratum spinosum-layer that is thickest-most number of layers-polyhedral cells-where ceramide is formed (intra lipid), the granules are called lamellar granules (lamellar bc the structure of the lipid is lamellar -> it's in layers)s. granulosum-keratohyalin granules which produce filaggrin (binds the keratin filaments together)

13thick vs thin skin

diff is the thickness of the corneum and the depth of interdigitation b/n epi &dermisinterdigitations -> to grasp and hold objects

14melanocyte-produces melannin-uv barrier (it can damage ur dna and cause cancer)langerhands cell-immune cell for surveys for potential harmful cells or chemicals/aggreatesmerkel cell-sensory receptor-found in base as well

THOSE 3 CELLS ARE NOT CONNECTED BY DESMOSOMES of the keratinocytes-usually appear rounded

melanocyte-neural crest-derived-dendritic cells (lots of processes)-basal-unique: the melanin granules are not in the actual cell but in the processes and transferred to the adjacent cells-appears as clear (bc cytoplasm are around it bc the processes are scattered); r



ounded; in the basal layer-melanin granules are found more in the adjacent keratinocytes-fontana-masson stain-also in the dark skin, the melanin reaches up to the s. corneum (so higher UV protection)-melanin granules vs melanosomes (organelles, actively producing melanin granules, found in melanocytes)-melanin granules packaged into Sgs transferred to keratinocytes -> INCLUSIONS (not organelles! no enzymes like tyrosinase)pheomelanin in fair skineumelanin for dark skin

langerhans cell-mid-epidermis-dendritic-bone marrow derived-also round with clear space around it-part of mononuclear phagocytic system, fxns like macrophage-APC-unique feature: HIGHLY INDENTED NUCLEAUS-BIRBECK GRANULES IN CYTOPLASM-special stain: gold chloride or immunostaining

DERMIS

-support layer for epi-elasticity & tensile strength due to dence irregular CT (fibers, ground substance, connective tissue cells like fibroblast -> main cell of dermis?)-nutirtion-highly vascular-nourishes episdermis over it; proveds THERMOREGULATION due to vasoconstriction

24epidermal-dermal attachmentincrease SA of attachment-peg & socket interdigitationepidermal rete ridges - downward area of epidermisdermal papillae - upward dermis

basal lamina -in bertween them; found in all interbasal epithelium CT

252 layers of dermispapillary-thinner-directly inderneath-contauns the dermal papillae-LOOSE CT-fibers are thin & overshadowed-CONTAINS CAPILLARIES, cells, ground substance-DIFFUSION OF NUTRIENTSreticular

-DENSE IRREGULAR CT-fibers are thick & prominent-tensile strength and elasticityelastic fibers-thicker in the reticular layer-ORCEIN STAIN

29extensive vascular networks-to appdenages as well (EPIDERMAL DERIVATIVES) in dermis & hypodermis



-to epidermis (plexus in dermal papillae)

30THERMOREGULATORY FXN DUE TO GLOMUS BODIESwhich acts as shuntsconserve heat by diverting blood from arteries directly into the veins without passing thru capillariestips of fingers and toes and ears

32ECCRINE GLANDSmost abundant skin glandthermoregulation (secret sweat -> evaporates -> body heat also dissipated)-excretory - a kind of exocrine glandMEROCRINE TYPE OF SECRETIONdirectly opens to skin surface (via SWEAT PORES)SIMPLE COILED TUBULARcoiling ue to more SA for formation, modification of swratsingle duct: 3 segments-intraepidermal duct coiled-straight dermal duct-coiled dermal ductsecretory coiled tubules

35IN LM CROSS SECTIONSductal vs secretory portion-secretory has bizarre shaped-ductal portion is dark pink, stratified cuboidal, luminal cuticle-secretory portion is a single layer of lightly eosinophilic pyramidal cells

37intraepidermal eccrine ductacrosyringium

38fingerprints unique to you alone; ridges due to the deep interdigitation b/n epi

dermis & dermisSWEAT-clear odorless fluidpredominantly NaClalso with urea, lactate, ammonia, amino acids, proteins, drugs (ketoconazole)

39skin as a secretory organ-merkel cell-neurite complex-touch-free nerve endings-pain, itch, temp&corpuscle - grp of cells arranged in a certain organization (meissner - cocoon;

pacinian - onion)2 encapsulated in ur slidesmeissner - touchpacinian - pressure/vibration

40MERKEL CELL-basal epidermal layer-closely apposed w/ nerve ending in papillary dermis-dense core granules (both nerve & secretory fxns)



-fxn: touch (SLOWLY ADAPTING-it will take a while before it is trigger; meissner - mabilis matrigger but after a while it will not fire anymore -> fast adapting)abundant in fingertips

pacinian-hard to miss bc it's very big-20-60 concentric lamellae around a central axon-deep dermis/hypod-fingertips/jts

meissner-small-in dermal papillae-spirally coursing axon surrounded by lamellae (=twisted skein of wool)-lips, fingertips/toes-light touch but rapidly adapting

45skin appendageshairnailglandseccrine

sebaceousapocrinevellus - everywhere except those areasterminal eye brows, etc pubic axillary hair

47layer of hair collicles similar to layers of epidermis bc it's just an invaginationpilosebaceous unit - sebaceous gland, arrector pili muscle, CT sheath, hair follicle-diff b/n hair shaft and s. corneum?hair shaft = hard keratinl sulfur-rich and closely packed bc of no filaggrin ->WONT BE DESQUAMATED CELL BY CELL!

hair follicle3segments:-infundibulum

opens into skin surfacewhere sebaceous gland empties"bulge" - stem cells

-inferior segmennt (only during growing stage and then disappears)hair bulb-hair matrix/root-melanocytes-hair papilla or dermal papilla (when it stops growing, hihiwalay itong dermal papillae)

-dapat teardrop shaped-enclosed by s. basaleconoc layers of HFhair shaftinternal root sheath - intimately assoc w/ hair shaft (sabay mag-grow)external root sheath-continuous w/ surface epidermis-hair matrix-vaculoted (glycogen)fibrous sheath



-also contains melanocytes

55stages in hair cycle1. growing (anagen) - longest stage bc of the close intimate assoc w hair matrix & hair papillae2. regressing (catagen) - shortest3. resting (telogen)

57what determines hair length-determined by genes-duration of anagen = determines maximum hair length-eyelashes 6 weeks-scalp 3 years-8/10 hair follicles in ANAGEN (TEARDROP SHAPE)club hair 0 regressing/catagen

59SEBACEOUS GLAND-simple branched alveolar glandholocrinesebum - triglycerides

-softens thin skin & makes hairs flexibleAPOCRINE-like eccrine bc it's also simple coiled tubular-merocrine type secretionBUT unlike eccrine-axillae, mons pubis, circumanal region-polosebaceous unit-milky, s. viscuous, odorless-pheromones-LARGER LUMEN-cells are MORE EOSINOPHILIC-apical blebs2. reg

Documents

Gross Anatomy: The Skin