Integument Flashcards
Integument
Skin (epidermis, dermis, hypodermis); hair, nails, glands, cutaneous nerves
Integument Functions
1) Protection- mechanical, thermal , chemical UV radiation, dehydration
2) Thermoregulation- vascular network in dermis, sweat glands
3) Sensory- touch, temperature, pain
4) Metabolic- Vitamin D synthesis in epidermis, energy storage (fat in hypodermis)
5) Excretion of excess water, salt, nitrogenous metabolic wastes through sweat
Thick Skin
palms of hands and soles of feet; no hair follicles
Thin Skin
skin other than palms and soles; thinner epidermis and hair follicles, but some exceptions
Epidermis (epith. cell type/ composition)
stratified squamous ep. cells = keratinocytes (produce keratin)
Layers of epidermis
stratum 1) basale (germinativum) 2) spinosum 3) granulosum 4) lucidum 5) corneum
Stratum Basale
single layer of columnar to cuboidal cells; mitotic figures; intermediate filaments (10 nm tonofilaments); desmosomes on lateral and upper surface, hemidesmosomes bind cells to basal lamina
Stratum spinosum
cuboidal, polygonal, slightly flattened; mitotic figures; intermediate filaments; terminate with desmosomes; accumulate FIBRILLAR protein (cytokeratin)- aggregate to form tonofibrils (visible w/ LM)
Stratum granulosum
3-5 layers of flattened polygonal cells; cytoplasm has basophilic keratohyaline granules and oval/rod-like lamellar granules visible by TEM
Lamellar granules of S. granulosum
(keratinosomes) formed by lipid bilayers which fuse with cell membrane & discharge contents into intercellular space of S. granulosum
Stratum Lucidum
only in thick skin, but not always evident; thin layer of eosinophilic, newly keratinized cells; NO organelles or nuclei evident; contain eleidin
eleidin
transformation product of keratohyalin in st. lucidum
stratum corneum
15-20 layers of flattened nonnucleated cells filled with keratin
squames
dead, flattened cells
epidermis skin healing
surrounding basal cells migrate and divide to cover the wound
Retinol
Vitamin A = factor needed for keratinocyte differentiation, required for proper skin healing
1st degree burn
extends to s. lucidum
2nd degree burn
extends to s. basale
3rd degree burn
extends into dermis
Filaggrin
protein aggregates keratin filaments
Keratinocytes in s. granulosum
glycolipids secreted to form lipid layer on the outside of the cell membrane
Keratinocytes in s. corneum
a protein complex of involucrin, small proline-rich, proteins, and loricin complex with keratin-filagrin aggregates and link to the cytoplasmic side of the cell membrane
Melanocytes origin
from neural crest cells; present in s. basale, rest on b. lamina and send cell processes into the s. spinosum
Melanocytes function
pigment producing; distribute melanin to other cells & hair via processes (cytocrine secretion); pigment granules are exocytosed and are endocytosed by keratinocytes
Melanin formation occurs within ___ (derived from ____).
melanosomes; Golgi
Addison’s Disease
lack of cortisol from adrenal cortex–>overproduction of ACTH–>increase skin pigmentation
Albinism
melanocytes don’t make melanin; vision problems due to abnormal retina development & abnormal nerve connections between the eye & brain
Vitiligo
melanocytes are destroyed- patchy pigmentation
Langerhans’ cell shape and location
“star shaped”- mainly in s. spinosum, occasionally in dermis near blood vessels
Derivation of Langerhans’ cells
bone marrow (macrophage lineage)
Function of Langerhans’ cells
- have Fc and complement C3 receptors
- can migrate out of epidermis to lymph nodes & present antigens to T cells
- differentiate into activated dendritic cells
Langerhans’ cells do not form ___ attachments with other cells.
desmosomal
Birbeck or vermiform granules
unique membrane-bound, rod-like to racquet shaped granules that contain proteins (langerin) necessary for antigen uptake (in Langerhan’s cells)
Merkel’s Cells
tactile epithelioid cell associated with sensory nerve ending; two-point discrimination; primarily in thick skin
Merkel’s cytoplasm
small dense granules- may be related to catecholamine containing granules of neurosecretory cells
Base of Merkel’s cell contact
peripheral neuron terminal (sensory receptors)
Merkel’s cell carcinoma
when merkel’s cells become cancerous; may be associated with polyoma virus
Dermis Function
composed of CT that supports epidermis & binds it to the subcutaneous tissue (hypodermis)
Dermal papillae
how surface dermis interdigitates with epidermis
Epidermal ridges/ rete ridges
epidermal counterpart to dermal papillae; epidermis extensions into dermis
Anchoring fibrils
collagenous extensions from basal lamina & terminate in anchoring plaques to bind the dermis to the epidermis
Papillary layer of dermis
outermost layer (loose CT) of dermis ; fibroblasts, mast cells and macrophages may be present
Reticular layer of dermis
composed of dense irregular CT; thicker that papillary layer
Components of dermis
follicles, sweat & sebaceous glands, nerves; extensive capillary network in the papillary layer functions in thermoregulation
Hypodermis
deeper continuation of dermis; primarily loose CT and adipose tissue; PACINIAN CORPUSCLES
Hair follicle
invagination of epidermis; terminates in hair bulb
Making of hair bulb and root
dermal papilla project into hair bulb; epidermal cells covering the dermal papilla for the hair root–>hair shaft
Hair Medulla
cells at the apex of dermal papilla produce large, vacuolated, moderately keratinized cells –> hair medulla
Hair Cortex
cells around papilla differentiate into fusiform, heavily keratinized cells
Cells more peripheral to the hair root produce the ___.
Hair cuticle
most peripheral root cells
Internal and external root sheath
glassy membrane
hair follicle separated from the dermis by a thickened basal lamina
arrector pili
smooth muscle bundles extending from dermis papillary layer to hair follicle connective tissue sheath
sebaceous glands
not found on palms and soles; holocrine glands
Acini
basal layer of undifferentiated flattened epithelial cells on basal lamina; as cells proliferate and differentiate, gland acini fills with cells containing fat droplets and nuclei become pyknotic, cells burst and release contents
Sebum
dead cells + cell contents in sebaceous glands
sudoriferous (sweat) glands
eccrine (merocrine); simple coiled tubular gland; duct opens onto skin surface; receive cholinergic nerve fibers; the secretory portion is in dermis
cells of sweat gland
myoepithelial (contractile), dark, and clear
Dark cells of sweat gland
mucoid, pyramidal; secrete glycoproteins
Clear cells of sweat gland
devoid of secretory granules; abundant glycogen; secrete water & electrolytes into intercellular canaliculi
non-viscous secretion of sweat gland contains…
little protein, contains water, NaCl, urea, ammonia, uric acid (ultrafiltrate of plasma)
Location of apocrine glands
axillary, areolar, and anal regions
Apocrine gland secretion
only one kind of secretory cell; secretion is viscous and protein rich; APOCRINE SWEAT GLANDS HAVE A MEROCRINE MECHANISM ODF SECRETION (that was underlined)
Composition of nails
plates of keratinized epithelial cells
Eponychium
= cuticle. stratum corneum of the epithelium covering the nail root
Nail bed
contains only s. basale and s. spinosum; nail plate rests here
Nail matrix
extends from the nail root to the lunula (white crescent and the base of the nail); nail plate arises from the nail matrix
Liver spots
not related to the liver (that’s frustrating…) just a good ole’ freckle due to being in the sun
actinic keratosis
precancerous condition; thick scaly patches of skin
basal cell carcinoma
90% of all skin cancers; slow growing & treatable if found early
squamous cell carcinoma
often develop from sun damaged areas (actinic keratosis due to sun damage)
malignant melanoma
derived from melanocytes; hard to treat once metastasized
psoriasis
immune mediated, genetic disease; red scaly patches of skin due to inflammation and hyperplasia; often associated with joint problems (psoriatic arthritis)
How long does it take epidermal keratinocytes to mature?
25-50 days
Epidermal epithelial cells accumlate more ___ as they migrate from ___.
keratin; basal layer
Product discharged by lamella granules of s. granulosum
glycolipid (acylglucoceramide)- serves as a penetration barrier to foreign materials & to maintain hydration of the body
What enzyme is needed for melanin synthesis?
tyrosinase
Specific granules in Langerhans’ cells
Birbeck/vermiform granules
PACINIAN CORPUSCLES
pressure/vibration sensors… (that look like onions on pizza from puccini’s) are found at dermis-hypodermis junction
Innervation of apocrine gland secretion
adrenergic innervation
