Glandular EpitheliumGland: a single cell or a mass of epithelial
cells adapted for secretionderived from epithelial cells that sank
below the surface during developmentEndocrine glands are
ductless.They secrete their products into ducts that empty at the
surface of covering and lining epithelium or directly onto a free
surface . Glandular EpitheliumExocrine glandscells that
secrete---sweat, ear wax, saliva, digestive enzymes onto free
surface of epithelial layerconnected to the surface by tubes ducts!
unicellular glandsor multicellular glandsEndocrine glands secrete
hormones into the bloodstreamhormones help maintain homeostasis
Mechanisms for Glandular SecretionMerocrine Glands:Salivary
glandsSudoriferous sweat glands of the skinApocrine
Glands:Lactiferous tissue of the Mammary glandsApocrine sweat
glandsHolocrine Glands:Sebaceous (oil) glandsof the skin
Introduction to the Integumentary SystemThe skin and its accessory
structures make up the integumentary system.The integumentary
system functions to guard the body"s physical and biochemical
integrity, maintain a constant body temperature, and provide
sensory information about the surrounding environment.# large organ
composed of all $ tissue types%% s&uare feet '-% mm thick(eight
') lbs. TYPES OF SKINThin skin covers all parts of the body except
for the palms and palmar surfaces of the digits and toes.lacks
epidermal ridgeshas a sparser distribution of sensory receptors
than thick skin.Thick skin ).* to $.+ mm!covers the palms, palmar
surfaces of the digits, and solesfeatures a stratum lucidum and
thick epidermal ridgeslacks hair follicles, arrector pili muscles,
and sebaceous glands, and has more sweat glands than thin skin.
FUNCTIONS OF SKINThermoregulation,erspiration - its evaporation
lowers body temperatureflow of blood in the dermis is
ad.ustedShivering and constriction of surface vesselsraise internal
body temperature as neededExercisein moderate exercise, more blood
brought to surface helps lower temperaturewith extreme exercise,
blood is shunted to muscles and body temperature rises FUNCTIONS OF
SKINblood reservoir extensive network of blood vesselsprotection -
physical, chemical and biological barrierstight cell .unctions
prevent bacterial invasionlipids released retard evaporationpigment
protects somewhat against /0 light1angerhans cells alert immune
systemcutaneous sensations touch, pressure, vibration, tickle,
heat, cold, and pain arise in the skin FUNCTIONS OF SKINSynthesis
of Vitamin D activation of a precursor molecule in the skin by /0
lightenzymes in the liver and kidneys modify the activated molecule
to produce calcitriol, the most active form of vitamin 2.necessary
vitamin for absorption of calcium from food in the gastrointestinal
tractexcretion$)) m1 of water3day, small amounts salt, 45%, ammonia
and urea Introduction to the Integumentary System Integumentary
SystemCutaneous membrane,rotects tissues from physical trauma,
biological pathogens, and chemical trauma,rovides
sensationsccessory Structures,rovides sensations,roduces
secretions,rotects epidermal surfaces Cutaneous
MembraneEpidermis:4ontrols skin permeability,revents entry of
biological pathogens6ynthesizes vitamin 2Dermis:7ourishes and
supports epidermis8estricts spread of pathogens6tores
lipids#ttaches skin to underlying tissue6ensory receptors provide
sensations9lood vessels assist in thermoregulation Accessory
Structures!air "ollicles:,roduce hair that protects underlying
skin,rovide sensations#ails:,rotect and support the tips of fingers
and toesExocrine Glands:#ssist in thermoregulation:xcrete
wastes1ubricate epidermis and hair,roduce pheromones for chemical
communication Specific Layer of the SkinEpidermis: 4omposed of
keratinized stratified s&uamous epitheliumDermis: ,apillary
region composed of areolar tissue 8eticular region composed of
dense irregular connective tissue!ypodermis: 4omposed of areolar
tissue with abundant adipocytes Specific Layers of the
EpidermisStratum $asale:;itotic layer, continuouslyreplaces
epidermal cells, turnover rate between %+ to +) daysStratum
Spinosum:4ells are pushed upward and flatten out6tratum eratin
Specific Layer of the EpidermisStratum %ucidum:5bserved only in
non-hairy or thick skin. 6everal layers of dead cells with
indistinct boundariesStratum Corneum:4omposed of %+ or more layers
of dead s&uamous cells still .oined by desmosomes.:ventually
desmosomes break and cells flake off in a process called
des&uamation Specialized Cells of the
Epidermis&eratinocytes:;ost common cells of the epidermis.
,rovides protection and waterproofing sealant'elanocytes:,roduces
and transfer the protein melanin to >eratinocytes.;elanin is a
brown3black pigment that absorbs /0-light. Specialized Cells of the
Epidermis%angerhans cells:#rise from red bone marrow and migrate to
the epidermis.They participate in immune responses against bacteria
and viruses.:asily damaged by /0'erkel Cells:?ound in the 6tratum
9asale, they contactthe flattened process of sensory neuron.They
respond to touch sensations 6kin 4olor ,igments'elanin produced in
epidermis by melanocytes melanocytes convert tyrosine to melanin /0
in sunlight increases melanin productionsame number of melanocytes
in everyone, but differing amounts of pigment producedresults vary
from yellow to tan to black color 4linical observations freckles or
liver spots @ melanocytes in a patchalbinism @ inherited lack of
tyrosinaseA no pigmentvitiligo @ autoimmune loss of melanocytes in
areas of the skin produces white patches The wide variety of colors
in skin is due to three pigments - melanin, carotene, and
hemoglobin in blood in capillaries! - in the dermis. 6kin 4olor
,igmentsCarotene in dermis=yellow-orange pigment precursor of
vitamin #!found in stratum corneum - dermis !emoglobin in
dermis=red, oxygen-carrying pigment in blood cellsif other pigments
are not present, epidermis is translucent so pinkness will be
evident Layers of the DermisDermis(eticular region:consists of
dense irregular 4T4ontain most of the accessory 6tructures)*
+apillary (egion:4onsist of areolar Tissue,* Dermal
+apilla:?ingerlike pro.ections that greatly increase surface
area1
!" Accessory Structures of the Dermispocrine s-eat glands:?ound
in the #xillae, nipples, labia, and glans penis.9egin to function
at puberty and are affected by hormones,roduce odorous thick
secretion,ossible pheromone function Sudoriferous .eccrine/S-eat
Gland:(idespread B,)))3s&. in.!,roduce thin watery
secretion4ontrolled by nervous systemThermoregulation:xcretion of
urea#ntibacterial action Sudoriferous Sweat #land Accessory
Structures of the DermisSebaceous 01il2 gland: 6ecrete sebum 4oats
hair shaft and lubricates the epidermis 6ecreted to hair follicles
7ot association with hair on the labia, glans penis, and lips
#ctivity controlled by sex-hormones ;odified in external ear canal
to produce cerumen or ear wax ceruminous glands! Accessory
Structures of the Dermis'ammary Glands:#natomically related to
apocrine sweat glands2evelopment controls by sex hormones and
pituitary hormones,roduce milk Accessory Structures of the
DermisCeruminous Glands:;odified sweat glands found in the external
auditory canal,roduce cerumen or ear waxCelps trap foreign
particles from reaching the eardrum Accessory Structures of the
Dermis!air:,resent on most skin except palmer surface, and plantar
surface