Integumentary System Flashcards
components of integumentary system
- skin
2. epidermal derivatives
major functions of integumentary system
- protective
- immunologic
- homeostasis
- sensory
- endocrine
- exocrine
two principle layers of skin
- epidermis
2. dermis
what tissue type is present in the epidermis?
keratinized stratified squamous epithelium
what germ later is the epidermis derived from?
ectoderm
what tissue type is found in the dermis?
connective tissue
what germ layer is the dermis derived from?
mesoderm
what is deep to the skin, and what is it composed of?
Hypodermis/subcutaneous layer/ subcutaneous fascia
vascularized adipose tissue
thick vs thin skin
thick: on palms of hands and soles of feet, hairless, thicker epidermis
thin: everywhere thick isn’t, hair follicles present, thinner epidermis
Epidermal layers
- stratum basale
- stratum spinosum
- stratum granulosum
- stratum lucidum (only in THICK skin)
- stratum corneum
cells found in the epidermis
keratinocytes (85%)
melanocytes (5%)
langerhan’ cells (2-5%)
merkel’s cells (6-10%)
keratinocytes
principles cell type of epidermis, produce keratins (structural protein of epidermis), produce lamellar bodies,
lamellar bodies
tubular/ovoid shaped membrane bound organelles, contain lipid,form water barrier
stratum basale
single layer of basophilic cells, simple cuboidal/simple low columnar, mititically active, contain stem cells, production of intermediate filaments (tonofilaments) begins
stratum spinosum
keratinocytes exhibit spines, cell processes attaches to adjacent cells via desmosomes, tonofilments –> tonofibrials (via keratohyalin) begins, lamellar bodies form
stratum granulosum
intensely basophilic, tonofibrils complete, keratinization occurs, lamellar bodies released
keratinization
conversion of granular cells into cornified cells
stratum lucidum
only in thick skin, thin translucent layeer of eosinophilic cells, nucleus and cytoplasmic organelles disappear
stratum corneum
nuclei and cytoplasmic organelles absent, 85% filled w/ keratin, cells at surface sloughed off, glycolipids in EC space
function of melanocytes
productionand secretion of melanin (synthesized and stored in melanosomes)
Melanocytes
dendritic cells (round cell bodies in s. basale, processes in s. spinosum), melanosomes are transferred into keratinocytes
elongated nuclei surrounded by clear cytoplasm
why does melanin accumulate over the nuclei?
to protect the DNA from UV radiation
Langerhan’s cells
antigen presenting cells in s. spinosum, encounter and process antigens entering thru skin, present processed antigen to T lymphocytes
what are langerhan’s cells derived from?
Bone marrow
Merkel’s cells
mechanoreceptor associated w/ sensory nerve endings, in s. basale, contains neurosecretory granules, base is Merkel’s corpuscle
Merkel’s corpuscle
expanded plate like terminal of afferent nerve fibers at base of cells
Basal Cell Carcinoma
most common, resembles cells of s. basale, slow growing tumor
Squamous cell carcinoma
second most common, highly atipical cells at all levels of epidermis
Malignant melanoma
most serious form, originates from melanocytes, irregular pigmented, multicolor lesion
two layers of dermis
- papillary layer
2. reticular layer
Papillary layer
superficial layer of dermis, loose CT, have dermal papillae that project into epidermis
reticular layer
deep layer of dermis, consist of DCT, thicker than papillary layer but with fewer cells
Pacinian corpuscles
large oval structures found in dermis/hypodermis, detect pressure and vibration, myelinated nerve endings surrounded by capsule of concentric lamellae
Meissner;s corpuscles
tapered cylindrical structures, located in dermal papillae of hairless skin, flattened schwann cells form lamellae, detect light touch, unmyelinated nerve ending following spiral paths
types of epidermal skin appendages, and derivative
- hair and follicles
- eccrine sweat glands
- apocrine sweat glands’
- sebaceous glands
derived from down growths of epidermal epithelium during development
hair
elongated filamentous, keratinized structures hat project from follicles
hair follicle
responsible for production and growth of a hair
arrector pili muscle
SM extending from CT sheath surrounding hair follicle to pap. layer of dermis, contraction acsues hair to stand on end, role in insulation and symp innervation
eccrine sweat glands
widely distributed, simple coiled tubular gland, merocrine secretion, thermoregulatory, excretes wastes and excess salts
Secretory portion of eccrine sweat glands
double layer of epithelial cells, larger and lighter than duct cells, in deep dermis or upper hypodermis
Duct portion of eccrine sweat glands
narrower outside diameter and lumen than secretory portion, double layer of cuboidal cells, smaller and darker than secretory portion, lead to epidermal surface
apocrine sweat glands
in axillary and perineal areas, viscous, protein rich sweat secreted into hair follicles, merocrine secretion, coiled tubular glands with wide lumen, begin functioning at puberty, bacterial breakdown of sweat leads to BO
Secretory portion of apocrine sweat glands
very wide lumen, simple cuboidal epi, eosinophilic cytoplasm, in upper hypodermis/deep dermis
Duct portion of apocrine sweat glands
stratified cuboidal epi, narrow lumen, empties into follicle canal
sebaceous glands
everywhere except thick skin, branched acinar gland, secete sebum into hair follicle, holocrine secretion, involved w/ acne
