Chapter 5 The Integumentary System PDF

The Integumentary System\ Chapter 5 **Skin** Largest organ of the body {#largest-organ-of-the-body.ListParagraph} ------------------------- Composed of 2 distinct regions {#composed-of-2-distinct-regions.ListParagraph} ------------------------------ ### Epidermis -- {#epidermis.ListParagraph} #...

The Integumentary System\ Chapter 5 **Skin** Largest organ of the body {#largest-organ-of-the-body.ListParagraph} ------------------------- Composed of 2 distinct regions {#composed-of-2-distinct-regions.ListParagraph} ------------------------------ ### Epidermis -- {#epidermis.ListParagraph} #### Epithelial tissue - avascular {#epithelial-tissue---avascular.ListParagraph} ### Dermis -- lies under epidermis {#dermis-lies-under-epidermis.ListParagraph} #### Mostly fibrous connective tissue- vascularized {#mostly-fibrous-connective-tissue--vascularized.ListParagraph} #### Nutrients diffuse through to reach epidermis {#nutrients-diffuse-through-to-reach-epidermis.ListParagraph} **Skin** Hypodermis (superficial fascia) {#hypodermis-superficial-fascia.ListParagraph} ------------------------------- ### Subcutaneous layer deep to skin {#subcutaneous-layer-deep-to-skin.ListParagraph} ### [ Not] a part of the skin {#not-a-part-of-the-skin.ListParagraph} ### Mostly adipose tissue that absorbs shock, stores fat & insulates {#mostly-adipose-tissue-that-absorbs-shock-stores-fat-insulates.ListParagraph} ### Anchors skin to underlying structures -- mostly muscles {#anchors-skin-to-underlying-structures-mostly-muscles.ListParagraph} ### Fascia -- fibrous membrane covering, supporting, and separating muscles {#fascia-fibrous-membrane-covering-supporting-and-separating-muscles.ListParagraph} ----------------------------------------------------------------------- **Cells of the epidermis** Keratinocytes: most cells of the epidermis {#keratinocytes-most-cells-of-the-epidermis.ListParagraph} ------------------------------------------ ### Produce keratin; a fibrous protein {#produce-keratin-a-fibrous-protein.ListParagraph} ### Tightly joined by desmosomes {#tightly-joined-by-desmosomes.ListParagraph} Melanocytes: synthesize melanin {#melanocytes-synthesize-melanin.ListParagraph} ------------------------------- ### Found in deeper layers of epidermis {#found-in-deeper-layers-of-epidermis.ListParagraph} ### Send processes between keratinocytes {#send-processes-between-keratinocytes.ListParagraph} ### Protect apical surface of keratinocyte nucleus from UV damage {#protect-apical-surface-of-keratinocyte-nucleus-from-uv-damage.ListParagraph} Dendritic (Langerhans) cells: macrophages {#dendritic-langerhans-cells-macrophages.ListParagraph} ----------------------------------------- Tactile (Merkel) cells: sensory touch receptors {#tactile-merkel-cells-sensory-touch-receptors.ListParagraph} ----------------------------------------------- **Layers of Epidermis** Thick skin: found in areas subject to abrasion {#thick-skin-found-in-areas-subject-to-abrasion.ListParagraph} ---------------------------------------------- ### Palm, fingertips, soles of feet {#palm-fingertips-soles-of-feet.ListParagraph} ### Five layers (strata) {#five-layers-strata.ListParagraph} Thin skin {#thin-skin.ListParagraph} --------- ### Four layers {#four-layers.ListParagraph} **Stratum basale (basal layer)** Also known as stratum germinativum {#also-known-as-stratum-germinativum.ListParagraph} ---------------------------------- Deepest epidermal layer {#deepest-epidermal-layer.ListParagraph} ----------------------- Single layer of cuboid shaped stem cells {#single-layer-of-cuboid-shaped-stem-cells.ListParagraph} ---------------------------------------- ### Actively mitotic {#actively-mitotic.ListParagraph} ### Produces two daughter cells {#produces-two-daughter-cells.ListParagraph} #### One cell migrates from basal layer to surface {#one-cell-migrates-from-basal-layer-to-surface.ListParagraph} ##### Takes 25-45 days {#takes-25-45-days.ListParagraph} ##### Dies as it moves toward surface {#dies-as-it-moves-toward-surface.ListParagraph} #### One cell remains as a stem cell {#one-cell-remains-as-a-stem-cell.ListParagraph} Melanocytes compose 10-25% of this layer {#melanocytes-compose-10-25-of-this-layer.ListParagraph} ---------------------------------------- ### **Stratum spinosum (prickly layer)** "Prickle cells" {#prickle-cells.ListParagraph} --------------- Several cell layers thick {#several-cell-layers-thick.ListParagraph} ------------------------- Contain tension-resisting bundles of pre-keratin filaments {#contain-tension-resisting-bundles-of-pre-keratin-filaments.ListParagraph} ---------------------------------------------------------- Keratinocytes appear to have spines {#keratinocytes-appear-to-have-spines.ListParagraph} ----------------------------------- ### Due to cell shrinkage but junctional complexes (desmosomes) hold tight {#due-to-cell-shrinkage-but-junctional-complexes-desmosomes-hold-tight.ListParagraph} Melanin granules and dendritic cells are most abundant in this layer {#melanin-granules-and-dendritic-cells-are-most-abundant-in-this-layer.ListParagraph} -------------------------------------------------------------------- **Stratum granulosum (granular layer)** Thin -- one to five cell layers {#thin-one-to-five-cell-layers.ListParagraph} ------------------------------- Cell appearance changes {#cell-appearance-changes.ListParagraph} ----------------------- ### Cells flatten {#cells-flatten.ListParagraph} ### Nuclei and organelles begin to disintegrate {#nuclei-and-organelles-begin-to-disintegrate.ListParagraph} ### Granules accumulate {#granules-accumulate.ListParagraph} #### Keratohyaline granules accumulate {#keratohyaline-granules-accumulate.ListParagraph} #### Lamellar granules {#lamellar-granules.ListParagraph} ##### Contain water-resistant glycolipids {#contain-water-resistant-glycolipids.ListParagraph} ##### Empty into extracellular space {#empty-into-extracellular-space.ListParagraph} Cells above this layer die: too far from dermal capillaries {#cells-above-this-layer-die-too-far-from-dermal-capillaries.ListParagraph} ----------------------------------------------------------- **Stratum lucidum (clear layer)** Only in thick skin {#only-in-thick-skin.ListParagraph} ------------------ Thin, translucent band superficial to the stratum granulosum {#thin-translucent-band-superficial-to-the-stratum-granulosum.ListParagraph} ------------------------------------------------------------ Two or three rows of flat, dead keratinocytes {#two-or-three-rows-of-flat-dead-keratinocytes.ListParagraph} --------------------------------------------- **Stratum corneum** Horny layer (cornu = horn) {#horny-layer-cornu-horn.ListParagraph} -------------------------- Thickest layer: 20-30 rows of dead, flat, anucleate keratinized membranous sacs {#thickest-layer-20-30-rows-of-dead-flat-anucleate-keratinized-membranous-sacs.ListParagraph} ------------------------------------------------------------------------------- F(x) of these dead cells {#fx-of-these-dead-cells.ListParagraph} ------------------------ ### Protect from abrasion and penetration {#protect-from-abrasion-and-penetration.ListParagraph} #### Keratin & thickened plasma membrane {#keratin-thickened-plasma-membrane.ListParagraph} ### Protect deeper cells from environment and water loss {#protect-deeper-cells-from-environment-and-water-loss.ListParagraph} #### Glycolipids {#glycolipids.ListParagraph} ### Barrier against biological, chemical, and physical assaults {#barrier-against-biological-chemical-and-physical-assaults.ListParagraph} **Cell Differentiation in Epidermis** Change from stratum basale to stratum corneum {#change-from-stratum-basale-to-stratum-corneum.ListParagraph} --------------------------------------------- ### Nucleus and organelles break down {#nucleus-and-organelles-break-down.ListParagraph} ### Plasma membrane thicken {#plasma-membrane-thicken.ListParagraph} ### Allows cells to slough off as dander and dandruff {#allows-cells-to-slough-off-as-dander-and-dandruff.ListParagraph} ### Shed \~ 50,000 cells every minute {#shed-50000-cells-every-minute.ListParagraph} **Dermis** Composed of connective tissues {#composed-of-connective-tissues.ListParagraph} ------------------------------ ### Supports the epidermis {#supports-the-epidermis.ListParagraph} ### Binds epidermis to hypodermis {#binds-epidermis-to-hypodermis.ListParagraph} Contains blood vessels, nerves, glands, & hair follicles {#contains-blood-vessels-nerves-glands-hair-follicles.ListParagraph} -------------------------------------------------------- Has two layers with indistinct boundaries {#has-two-layers-with-indistinct-boundaries.ListParagraph} ----------------------------------------- **Papillary Dermis** Superficial, thin layer of areolar connective tissue {#superficial-thin-layer-of-areolar-connective-tissue.ListParagraph} ---------------------------------------------------- ### Fibroblasts, mast cells, macrophages {#fibroblasts-mast-cells-macrophages.ListParagraph} Dermal papillae {#dermal-papillae.ListParagraph} --------------- ### Capillary loops {#capillary-loops.ListParagraph} ### Free nerve endings- pain receptor {#free-nerve-endings--pain-receptor.ListParagraph} ### Meissner's (tactile) corpuscles {#meissners-tactile-corpuscles.ListParagraph} #### Elongated receptor with a stack of supporting cells around a few spiraling sensory nerve endings {#elongated-receptor-with-a-stack-of-supporting-cells-around-a-few-spiraling-sensory-nerve-endings.ListParagraph} #### Sensitive to light touch {#sensitive-to-light-touch.ListParagraph} **Papillary Dermis** Dermal ridges -- found under dermal papillae in thick skin {#dermal-ridges-found-under-dermal-papillae-in-thick-skin.ListParagraph} ---------------------------------------------------------- ### Create epidermal ridges {#create-epidermal-ridges.ListParagraph} Friction ridges = dermal + epidermal ridges {#friction-ridges-dermal-epidermal-ridges.ListParagraph} ------------------------------------------- Sweat pores along friction ridges leave film of sweat on surfaces {#sweat-pores-along-friction-ridges-leave-film-of-sweat-on-surfaces.ListParagraph} ----------------------------------------------------------------- ### Fingerprints {#fingerprints.ListParagraph} **Reticular Dermis** \~ 80% of dermal thickness {#of-dermal-thickness.ListParagraph} -------------------------- Dense irregular connective tissue {#dense-irregular-connective-tissue.ListParagraph} --------------------------------- Collagen fibers {#collagen-fibers.ListParagraph} --------------- ### Provide strength and resiliency {#provide-strength-and-resiliency.ListParagraph} Elastic fibers provide stretch-recoil properties {#elastic-fibers-provide-stretch-recoil-properties.ListParagraph} ------------------------------------------------ Dermal vascular (cutaneous) plexus {#dermal-vascular-cutaneous-plexus.ListParagraph} ---------------------------------- Extracellular matrix contains pockets of adipose tissue {#extracellular-matrix-contains-pockets-of-adipose-tissue.ListParagraph} ------------------------------------------------------- **Reticular Dermis** Cleavage (tension) lines {#cleavage-tension-lines.ListParagraph} ------------------------ ### Separations between collagen bundles {#separations-between-collagen-bundles.ListParagraph} **09/25/2024** **Reticular Dermis** Flexure lines {#flexure-lines.ListParagraph} ------------- ### Dermal folds at or near joints {#dermal-folds-at-or-near-joints.ListParagraph} ### Dermis is tightly secured to deeper structures {#dermis-is-tightly-secured-to-deeper-structures.ListParagraph} **Reticular Dermis** Between interlacing collagen fibers... {#between-interlacing-collagen-fibers.ListParagraph} -------------------------------------- ### Nerves {#nerves.ListParagraph} ### Pocket of adipose tissue/ epidermal derivative {#pocket-of-adipose-tissue-epidermal-derivative.ListParagraph} ### Lamellar (Pacinian) corpuscle -- {#lamellar-pacinian-corpuscle.ListParagraph} #### Round receptor with concentric layers of supporting cells around a sensory nerve ending {#round-receptor-with-concentric-layers-of-supporting-cells-around-a-sensory-nerve-ending.ListParagraph} **Skin Color** The pigments contribute to skin color {#the-pigments-contribute-to-skin-color.ListParagraph} ------------------------------------- ### Melanin -- only pigment produced by the skin {#melanin-only-pigment-produced-by-the-skin.ListParagraph} ### Carotene -- yellow to orange pigment; accumulates in stratum corneum & hypodermis {#carotene-yellow-to-orange-pigment-accumulates-in-stratum-corneum-hypodermis.ListParagraph} ### Hemoglobin -- oxyhemoglobin in erythrocytes {#hemoglobin-oxyhemoglobin-in-erythrocytes.ListParagraph} **Melanin synthesis** Tyrosinase converts tyrosine into melanin {#tyrosinase-converts-tyrosine-into-melanin.ListParagraph} ----------------------------------------- Melanin granules are transferred to basal keratinocytes as melanosomes {#melanin-granules-are-transferred-to-basal-keratinocytes-as-melanosomes.ListParagraph} ---------------------------------------------------------------------- ### Granules accumulate on apical side of the nucleus in the cytoplasm; shielding DNA from damaging UV radiation {#granules-accumulate-on-apical-side-of-the-nucleus-in-the-cytoplasm-shielding-dna-from-damaging-uv-radiation.ListParagraph} ### Melanin granules fuse with lysosomes; enzymes breakdown melanin {#melanin-granules-fuse-with-lysosomes-enzymes-breakdown-melanin.ListParagraph} **Melanin** Number of melanocytes per unit area is not influenced by gender or race {#number-of-melanocytes-per-unit-area-is-not-influenced-by-gender-or-race.ListParagraph} ----------------------------------------------------------------------- Differences in skin color may be related to: amount of pigment, size of granules, how many melanin granules are found {#differences-in-skin-color-may-be-related-to-amount-of-pigment-size-of-granules-how-many-melanin-granules-are-found.ListParagraph} --------------------------------------------------------------------------------------------------------------------- ### The amount and kind of pigment produced and dispersed {#the-amount-and-kind-of-pigment-produced-and-dispersed.ListParagraph} ### \# of melanin granules in keratinocytes {#of-melanin-granules-in-keratinocytes.ListParagraph} **Melanin** "Tanning" {#tanning.ListParagraph} --------- ### Darkening of preexisting melanin & increase in rate of release {#darkening-of-preexisting-melanin-increase-in-rate-of-release.ListParagraph} ### Increased rate of synthesis {#increased-rate-of-synthesis.ListParagraph} #### UV exposure increases tyrosinase activity {#uv-exposure-increases-tyrosinase-activity.ListParagraph} Albinism Melanin synthesis by melanocytes is severely reduced or absent **Epidermal Derivatives** Skin appendages: {#skin-appendages.ListParagraph} ---------------- ### Hair and hair follicles {#hair-and-hair-follicles.ListParagraph} ### Nails {#nails.ListParagraph} ### Sweat glands {#sweat-glands.ListParagraph} ### Sebaceous (oil) glands {#sebaceous-oil-glands.ListParagraph} **Hair (pili)** Dead keratinized cells of hard keratin {#dead-keratinized-cells-of-hard-keratin.ListParagraph} -------------------------------------- Not in palms, soles, lips, nipples, portions of external genitalia {#not-in-palms-soles-lips-nipples-portions-of-external-genitalia.ListParagraph} ------------------------------------------------------------------ Functions of hair... {#functions-of-hair.ListParagraph} -------------------- ### Warn of insects on skin {#warn-of-insects-on-skin.ListParagraph} ### Hair on head protects against physical trauma, heat loss and sunlight {#hair-on-head-protects-against-physical-trauma-heat-loss-and-sunlight.ListParagraph} ### Eyelashes shield eyes {#eyelashes-shield-eyes.ListParagraph} ### Nose hairs filter {#nose-hairs-filter.ListParagraph} **Hair** Hard keratin vs. soft keratin of skin {#hard-keratin-vs.-soft-keratin-of-skin.ListParagraph} ------------------------------------- ### Tougher and more durable {#tougher-and-more-durable.ListParagraph} ### Individual cells do not flake off {#individual-cells-do-not-flake-off.ListParagraph} Root: embedded in skin {#root-embedded-in-skin.ListParagraph} ---------------------- Shaft: projects above skin surface {#shaft-projects-above-skin-surface.ListParagraph} ---------------------------------- **Hair** Medulla: central core {#medulla-central-core.ListParagraph} --------------------- ### Consists of large cells and air spaces {#consists-of-large-cells-and-air-spaces.ListParagraph} ### Contains soft keratin {#contains-soft-keratin.ListParagraph} ### Absent in fine hairs {#absent-in-fine-hairs.ListParagraph} Cortex: bulk of hair {#cortex-bulk-of-hair.ListParagraph} -------------------- ### Several layers of flattened cells {#several-layers-of-flattened-cells.ListParagraph} Cuticle: outermost layer {#cuticle-outermost-layer.ListParagraph} ------------------------ ### Single layer of cells that overlap each other {#single-layer-of-cells-that-overlap-each-other.ListParagraph} **Hair Follicle** Extends from epidermal surface to dermis {#extends-from-epidermal-surface-to-dermis.ListParagraph} ---------------------------------------- Two-layered wall -- part dermis, part epidermis {#two-layered-wall-part-dermis-part-epidermis.ListParagraph} ----------------------------------------------- Hair bulb: deep, expanded end {#hair-bulb-deep-expanded-end.ListParagraph} ----------------------------- ### Hair follicle receptor (root hair plexus) {#hair-follicle-receptor-root-hair-plexus.ListParagraph} #### sensory nerve endings {#sensory-nerve-endings.ListParagraph} Hair papilla: dermal tissue {#hair-papilla-dermal-tissue.ListParagraph} --------------------------- ### Provides blood supply {#provides-blood-supply.ListParagraph} **Hair Follicle** Peripheral connective tissue sheath {#peripheral-connective-tissue-sheath.ListParagraph} ----------------------------------- ### Derived from dermis {#derived-from-dermis.ListParagraph} Glassy membrane {#glassy-membrane.ListParagraph} --------------- ### Basement membrane of epithelial root sheath {#basement-membrane-of-epithelial-root-sheath.ListParagraph} Epithelial root sheath {#epithelial-root-sheath.ListParagraph} ---------------------- ### External root sheath: continuation of epidermis {#external-root-sheath-continuation-of-epidermis.ListParagraph} ### Internal root sheath: derived from matrix cells {#internal-root-sheath-derived-from-matrix-cells.ListParagraph} **Hair Follicle** Hair matrix {#hair-matrix.ListParagraph} ----------- ### Dividing cells of the hair bulb {#dividing-cells-of-the-hair-bulb.ListParagraph} ### Lie adjacent to hair papilla {#lie-adjacent-to-hair-papilla.ListParagraph} Arrector pili muscle: causes "goose bumps" {#arrector-pili-muscle-causes-goose-bumps.ListParagraph} ------------------------------------------ ### Smooth muscle attached to follicle {#smooth-muscle-attached-to-follicle.ListParagraph} **Nails** Scale-like modification of epidermis {#scale-like-modification-of-epidermis.ListParagraph} ------------------------------------ Protective protein coverings over distal phalanges {#protective-protein-coverings-over-distal-phalanges.ListParagraph} -------------------------------------------------- Contain hard keratin {#contain-hard-keratin.ListParagraph} -------------------- Nail growth occurs in nail matrix {#nail-growth-occurs-in-nail-matrix.ListParagraph} --------------------------------- **Sweat Glands** Sudoriferous glands -- 2 types {#sudoriferous-glands-2-types.ListParagraph} ------------------------------ ### Eccrine (merocrine) sweat gland {#eccrine-merocrine-sweat-gland.ListParagraph} ### Apocrine sweat gland {#apocrine-sweat-gland.ListParagraph} Widely distributed {#widely-distributed.ListParagraph} ------------------ ### All skin surfaces except nipples and parts of external genitalia {#all-skin-surfaces-except-nipples-and-parts-of-external-genitalia.ListParagraph} **Eccrine Sweat Glands** Most numerous {#most-numerous.ListParagraph} ------------- Abundant on soles, palms, and forehead {#abundant-on-soles-palms-and-forehead.ListParagraph} -------------------------------------- Ducts connect to pores {#ducts-connect-to-pores.ListParagraph} ---------------------- Simple coiled tubular gland {#simple-coiled-tubular-gland.ListParagraph} --------------------------- Merocrine secretion of sweat {#merocrine-secretion-of-sweat.ListParagraph} ---------------------------- ### Water, salts, metabolic waste... {#water-salts-metabolic-waste.ListParagraph} Functions for thermoregulation {#functions-for-thermoregulation.ListParagraph} ------------------------------ Functions throughout life {#functions-throughout-life.ListParagraph} ------------------------- **Apocrine Sweat Glands** Axillary and anogenital regions {#axillary-and-anogenital-regions.ListParagraph} ------------------------------- Merocrine secretion: empties into hair follicle {#merocrine-secretion-empties-into-hair-follicle.ListParagraph} ----------------------------------------------- Viscous sweat {#viscous-sweat.ListParagraph} ------------- ### True sweat + fatty substances and proteins {#true-sweat-fatty-substances-and-proteins.ListParagraph} Begins to function at puberty {#begins-to-function-at-puberty.ListParagraph} ----------------------------- Stinky sweat\... due to bacterial action {#stinky-sweat...-due-to-bacterial-action.ListParagraph} ---------------------------------------- **Modified Apocrine Sweat Glands** Ceruminous glands {#ceruminous-glands.ListParagraph} ----------------- ### Lining of external ear canal {#lining-of-external-ear-canal.ListParagraph} ### Secretes cerumen (earwax) {#secretes-cerumen-earwax.ListParagraph} ### Deter insects and block entry of foreign material {#deter-insects-and-block-entry-of-foreign-material.ListParagraph} Mammary glands {#mammary-glands.ListParagraph} -------------- ### Secrete milk {#secrete-milk.ListParagraph} **Sebaceous glands** Not in thick skin of palms and soles {#not-in-thick-skin-of-palms-and-soles.ListParagraph} ------------------------------------ Associated with a hair follicle {#associated-with-a-hair-follicle.ListParagraph} ------------------------------- ### Simple branched alveolar gland {#simple-branched-alveolar-gland.ListParagraph} ### Secretory portion in dermis {#secretory-portion-in-dermis.ListParagraph} ### Duct empties into a hair follicle or occasionally to a pore on skin surface {#duct-empties-into-a-hair-follicle-or-occasionally-to-a-pore-on-skin-surface.ListParagraph} Sebum: holocrine secretion {#sebum-holocrine-secretion.ListParagraph} -------------------------- ### Accumulated lipids & cell fragments {#accumulated-lipids-cell-fragments.ListParagraph} ### Acts as a protective film {#acts-as-a-protective-film.ListParagraph} ### Prevents drying, keep skin soft & kills bacteria {#prevents-drying-keep-skin-soft-kills-bacteria.ListParagraph} **Functions of Integumentary System** Protection {#protection.ListParagraph} ---------- Body temperature regulation {#body-temperature-regulation.ListParagraph} --------------------------- Cutaneous sensation {#cutaneous-sensation.ListParagraph} ------------------- Metabolic functions {#metabolic-functions.ListParagraph} ------------------- Blood reservoir {#blood-reservoir.ListParagraph} --------------- Excretion of waste {#excretion-of-waste.ListParagraph} ------------------ **Protection** Skin is our most vulnerable organ {#skin-is-our-most-vulnerable-organ.ListParagraph} --------------------------------- Chemical barriers {#chemical-barriers.ListParagraph} ----------------- ### Skin secretions {#skin-secretions.ListParagraph} #### Low pH (acid mantle) slows bacterial growth {#low-ph-acid-mantle-slows-bacterial-growth.ListParagraph} #### Sebum and components of sweat kill bacteria {#sebum-and-components-of-sweat-kill-bacteria.ListParagraph} ### Melanin provides defense against UV radiation damage {#melanin-provides-defense-against-uv-radiation-damage.ListParagraph} **Protection** Physical barriers {#physical-barriers.ListParagraph} ----------------- ### Flat, dead cells of stratum corneum surrounded by lipids {#flat-dead-cells-of-stratum-corneum-surrounded-by-lipids.ListParagraph} ### Keratin and glycolipids block most water and water soluble substances {#keratin-and-glycolipids-block-most-water-and-water-soluble-substances.ListParagraph} ### Limited penetration of skin {#limited-penetration-of-skin.ListParagraph} #### Lipid-soluble substances {#lipid-soluble-substances.ListParagraph} #### Plant oleoresins (i.e. poison ivy oils) {#plant-oleoresins-i.e.-poison-ivy-oils.ListParagraph} #### Organic solvents {#organic-solvents.ListParagraph} #### Salts of heavy metals (lead & mercury) {#salts-of-heavy-metals-lead-mercury.ListParagraph} #### Some drugs {#some-drugs.ListParagraph} #### Drug agents {#drug-agents.ListParagraph} **Protection** Biological barriers {#biological-barriers.ListParagraph} ------------------- ### Dendritic cells of the epidermis {#dendritic-cells-of-the-epidermis.ListParagraph} #### Present foreign antigens to WBC's {#present-foreign-antigens-to-wbcs.ListParagraph} #### Leave skin, migrate to nearest lymph node {#leave-skin-migrate-to-nearest-lymph-node.ListParagraph} ### Dermal macrophages {#dermal-macrophages.ListParagraph} #### present foreign antigens to WBC's {#present-foreign-antigens-to-wbcs-1.ListParagraph} **Body Temperature Regulation** Normal body temperature {#normal-body-temperature.ListParagraph} ----------------------- ### \~500 ml/day of routine insensible perspiration {#mlday-of-routine-insensible-perspiration.ListParagraph} Elevated body temperature {#elevated-body-temperature.ListParagraph} ------------------------- ### Dilation of dermal blood vessels {#dilation-of-dermal-blood-vessels.ListParagraph} ### Increased eccrine sweat gland activity {#increased-eccrine-sweat-gland-activity.ListParagraph} ### Sensible perspiration works to cool the body {#sensible-perspiration-works-to-cool-the-body.ListParagraph} Cold external environment {#cold-external-environment.ListParagraph} ------------------------- ### Dermal blood vessels constrict {#dermal-blood-vessels-constrict.ListParagraph} ### Skin temperature drops to slow passive heat loss {#skin-temperature-drops-to-slow-passive-heat-loss.ListParagraph} **Cutaneous Sensations (innervation)** Cutaneous sensory receptors: exteroceptors {#cutaneous-sensory-receptors-exteroceptors.ListParagraph} ------------------------------------------ ### Touch, pressure, temperature, and pain sensations {#touch-pressure-temperature-and-pain-sensations.ListParagraph} Efferent or motor information {#efferent-or-motor-information.ListParagraph} ----------------------------- ### Acts on integumentary effectors (muscle or glands) {#acts-on-integumentary-effectors-muscle-or-glands.ListParagraph} ### Goose bumps, sweat production {#goose-bumps-sweat-production.ListParagraph} **Other Functions** Metabolic functions {#metabolic-functions-1.ListParagraph} ------------------- ### Synthesis of Vitamin D precursor and collagenase {#synthesis-of-vitamin-d-precursor-and-collagenase.ListParagraph} ### Chemical conversion of carcinogens & activates some hormones {#chemical-conversion-of-carcinogens-activates-some-hormones.ListParagraph} Blood reservoir -- up to 5% of body's blood volume {#blood-reservoir-up-to-5-of-bodys-blood-volume.ListParagraph} -------------------------------------------------- Excretion -- nitrogenous wastes & salt in sweat {#excretion-nitrogenous-wastes-salt-in-sweat.ListParagraph} -----------------------------------------------