skin + appendages

(nails, hair, sweat glands, sebaceous glands)

• barrier
• provides immunological info
• conveys sensory info
• performs endocinre functions
• excretion
• thermoregulation:  blood flow, sweating

epidermis

dermis

NOT part of skin layers

below dermis

loss connective tissue w/ fat

large blood vessels

• interdigitation of epidermal reidges & dermal ridges (papillae)
• attach epidermis to dermis
• forms fingerprints:  dermatoglyphs

EPIDERMIS

type of epithelium

EPIDERMIS

derived from?

EPIDERMIS

vascular/avascular

EPIDERMIS

types

thick skin

thin skin

THICK SKIN

characteristics

glabrous

smooth

non-hairy

THICK SKIN

location

palm

soles

THICK SKIN

presence of hair follicles/sebaceous glands?

THIN SKIN

characteristics

hairy

3-4 layers

includes hair follicles, sebaceous and sweat glands

EPIDERMIS

layers

superficial to deep

stratum corneum

stratum lucidum

stratum granulosom

stratum spinosum

stratum basale

STRATUM BASALE

characteristics

basophilic cytoplasm

STRATUM BASALE

location

STRATUM BASALE

active division?

STRATUM BASALE

cellular components

• large nucleus
• abundant free ribosomes
• produce intermediate filaments (keratin):  tonofilaments
• Merkel's cells:  sensory nerve endings
• melanocytes:  skin color

STRATUM BASALE

cell adhesion

desmosomes:  b/w cells

hemidesmosomes:  b/w cell & basal lamina

STRATUM SPINOSUM

other name

STRATUM SPINOSUM

location

STRATUM SPINOSUM

mitosis?

STRATUM SPINIOSUM

# of cell layers

STRATUM SPINOSUM

shape

cuboidal or slightly flattened

central nucleus

STRATUM SPINOSUM

cell adhesion

filament-filled cytoplasmic spins and desmosomes

"spine-studded" appearance:  nodes of Bizzozero

STRATUM SPINOSUM

cellular components

• cytoplasm contains processes filled w/ numberous bundles of intermediate filaments (keratin):  tonofibrils
• Langerhands cells:  immune system

STRATUM GRANULOSUM

# of cell layers

STRATUM GRANULOSUM

cellular components

• last layer w/ nuclei
• lysosomal enzymes
• granules

STRATUM GRANULOSUM

types of granules

kertohyalin

lamellar

STRATUM GRANULOSUM

keratinocytes?

flattening keratinocytes from stratum spinosum

STRATUM GRANULOSUM

keratohyalin granules

associated w/ tonofibrils

act to help strengthen them

STRATUM GRANULOSUM

lamellar granules

discharge lipid-rich content

acts to serve as barrier for foreign materials

water-proofs skin

produced in Golgi

STRATUM LUCIDUM

thick/thin skin

STRATUM LUCIDUM

celluar componenets

STRATUM LUCIDUM

keratin?

STRATUM LUCIDUM

shape

STRATUM CORNEUM

# of layers

STRATUM CORNEUM

keratin?

STRATUM CORNEUM

cellular components

no nucleus

thick membranes

no organelles

STRATUM CORNEUM

cell adhesion

• deep layers:  desmosomes
• superficial layers:  loss of desmosomes, undergo desquamation

melanocytes

langerhan cells

merkel cells

MELANOCYTES

loction

MELANOCYTES

characteristics

primarily responsible for skin color

derived from neural crest

no desmosomes

MELANOCYTE

shape

MELANOCYTE

location

• long irregular extensions b/w s. basale and s. spinosum
• move to supranuclear region of cells:  protection for keratinocytes

MELANOCYTES

cellular components

numerous mitochondria

no desmosomes

RER:  produces melanin precursor

Golgi:  packages melanosomes

activity activated by UV light

LANGERHAN CELLS

location

LANGERHANS CELLS

cellular components

irregularly-shaped nuclei

pale staining cytoplasm

long slender processes

no desmosomes

Birbeck granules

LARGERHANS CELLS

origin

LANGERHANDS CELLS

function

LANGERHANS CELLS

Birbeck granule characteristics

rod like structures w/ regular striations

unknown function

MERKEL CELLS

location

mainly in stratum basale

abundant on finger tips

MERKEL CELLS

characteristics

associated w/ sensory nerve endings

may function as mechanoreceptors

MERKEL CELLS

cell adhesion

form desmosomes w/ s. spinosum

share basal lamina w/ s. basale

• greater epidermal thickness
• rapid renewal of epidermis
• increase in # of proliferating cells in s. basale & s. spinosum
• keratinocytes accumulate in s. corneum
• decrease in cycle time

one of most common skin cancers

sun-exposed areas (nose)

from s. basale

slow growing

central crater

non metastatic

• malignant tumor airising from melanocytes in deeper layers of epidermis
• highly metastatic

DERMIS

characteristics

• connective tissue layer deep to epidermis
• separated from stratum basale by basement membrane
• thicker in men and dorsal aspect of body

DERMIS

function

DERMIS

vascular/avascular

DERMIS

origin

LANGER LINES

define

LANGER LINES

function

determines tension & wrinkle lines in skin

dtermines pace & nature of wound healing

LANGER LINES

use for incision

• cut parallel to lines:  less gapping, faster healing, less scar tissue
• cut perpendicular to lines:  increase time of healing, increase scar tissue formation

DERMIS

layers

papilary

reticular

DERMIS

papillary layer

loose connective tissue

interdigitates w/ epidermis

separated by basement membrane

rete apparatus

PAPILLARY LAYER

composition

• loose connective
• collagen fibers (I, II, some III)
• elastic fibers
• anchoring fibrils (from basal lamina)
• Meissner's corpuscles

DERMIS

reticular layer

• dense irregular
• connective
• network
• NOT abundance of reticular fibers

RETICULAR LAYER

composition

• Type I
• thick elastic fibers
• smooth muscle (arrector pilli)
• epidermally derived glands
• hair follicles
• Pacinian corpuscles

1. epidermis destroyed
2. epidermis + dermis destroyed
3. epidermis, dermis and hypodermis destroyed

SKIN APPENDAGES

origin

SKIN APPENDAGES

hair

• elongated
• keratinized
• derived from invaginations of epidermal epithelium 

SKIN APPENDAGES

nails

keratinized

plate of epithelial cells

dorsal surface of phalanx

SKIN APPENDAGES

components of nails

• nail bed:  continuous w/ s. basale and s. spinosum
• nail:  continuous w/ s. corneum

SKIN APPENDAGES

sebaceous gland products

• sebum:  waxy texture
  • cholesterol, triclycerides, cell debris
• holocrine secretion

SKIN APPENDAGES

sebaceous gland location

all over body

most abundant on face, forehead & scalp

exceptions:  palms, soles, sides of feet

SKIN APPENDAGES

sebaceous gland function

• may aid in hair flexibility and help maintain proper skin texture
• lie w/in fibrous sheath surrounding each hair follicle
• cradeled by arrector pilli muscles
• packed w/ lipid filled vacuoles

SKIN APPENDAGES

sebaceous glands:  acinus

SKIN APPENDAGES

sebaceous glands:  holocrine secretion

• as secretory cell matures, dies and becomes part of secretory product
• desruction of cell

SKIN APPENDAGES

sebaceous glands:  ducts

stratified squamous epithelium

(usually ends in upper portion of hair follicle)

SKIN APPENDAGES

sebaceous glands:  secretion

males:  testosterone controls

females:  estrogen & adrenal androgens control

SKIN APPENDAGES

sweat gland location

SKIN APPENDAGES

sweat gland types

eccrine

apocinre

SKIN APPENDAGES

eccrine sweat gland shape

simple coiled tubular

invaginations of epithelium into dermis/hypodermis

SKIN APPENDAGES

eccrine sweat gland fuction

SKIN APPENDAGES

eccrine sweat gland ducts

open on skin surface:  sweat pores

NOT associated w/ hairs

SKIN APPENDAGES

eccrine sweat glands:  mode of secretion

SKIN APPENDAGES

apocrine sweat gland shape

• larger than eccrine
• simple coild tubular
• simple cuboidal to low columnar eosinophilic secretory cells

SKIN APPENDAGES

apocrine sweat glands:  ducts

straight

do not resorb fluid

SKIN APPENDAGES

apocrine sweat glands:  location

open into canals of hair follicles

superficial to entry of sebaceous gland ducts

SKIN APPENDAGES

apocrine sweat gland:  activated when

SKIN APPENDAGES

apocrine sweat gland:  component

SKIN APPENDAGES

modified apocrine cells

external auditory canal:  ceruminous/wax glands

eyelid:  glands of Moll

NOT apocrine secretion, instead merocrine

SKIN APPENDAGES

sensory nerve endings

SKIN APPENDAGES

types of sensory nerve endings

capsulated

non-encapsulated

MEISSNER'S CORPUSCLES

location

MEISSNER'S CORPUSCLES

characteristics

• small, encapsulated oval sensory receptors
• rapidly adapting mechanoreceptors
• touch sensation
• flattened Schwann cells

PACINIAN CORPUSCLES

characteristics

• encapsulated sensory receptors
• concentric layers of flattened cells
• deep pressure
• vibration

PACINIAN CORPUSCLES

location

• consist of numerous small terminal branches of afferent nerve fibers
• conveey temp, touch, and pain