Integumentary System Flashcards
Components of Integumentary system
Skin & Epidermal Derivatives (hair, follicles, glands, nails)
Major Functions of Integumentary
protective, immunologic, homeostasis, sensory, endocrine, exocrine
Skin consists of two principle layers:
epidermis & dermis
Epidermis
superficial layer of skin - keratinized stratified squamous - ectoderm derivative - avascular
dermis
connective tissue - derived from mesoderm - highly vascularized
Thick Skin
found on palms and soles only - skin is hairless - much thicker epidermal layer than any other location
Thin Skin
found everywhere except palms and soles - much thinner layer - hair present in most places
Thin Skin Layers
4 layers - bottom to top (basale, spinosum, granulosum, corneum)
Thick Skin Layers
5 layers - bottom to top (basale, spinosum, granulosum, lucidum, corneum)
Cells of epidermis:
Keratinocytes (85%), Melanocytes (5%), Langerhan’s Cells (2-5%), Merkels cells (6-10%)
kertatinocytes
principle cell type of epidermis - produce keratins (structural protein of epidermis) - form tonofilaments - participate in formation of water barrier by production of lamellar bodies (lipids)
Stratum Basale Layer
single layer of basophilic cells - cuboidal shaped - mitotically active layer with stem cells that produce the keratinocytes & tonofilaments
stratum spinosum
keratinocytes with spinous cytoplasmic processes - attached to adjacent cells via desmosomes - tonofilaments are bundled to form tonofibrils - begin productio of keratohyalin granules & lamellar bodies
stratum granulosum
keratinocytes contain the formed keratohyaline granules - conversion of granular cells into cornified cells (keartinization)
stratum lucidum
only found in thick skin - thin, translucent (white) layer of eosinophilic cells - nucleus & cytoplasm organelles become disrupted & disappear
stratum corneum
cells lose nuclei & cytoplasmic organelles - mostly keratin (85%) - sloughed at the surface
melanocytes
produce & secrete the pigment melanin - dendritic cells found in stratum basale - long processes extend upward between keratinocytes in the stratum spinosum - protects DNA from UV -
Langerhan cells
antigen presenting cells found within stratum spinosum - present antigen to T lymphocytes within the lymph node -
Merkel cells
mechanoreceptor cells associated with sensory nerve endings - usually within stratum basale - Merkel’s corpuscle (base of cells with terminal of aferent nerve fibers)
3 major types of skin cancer
Basal cell carcinoma, squamous cell carcinoma, malignant melanoma
Basal cell carcinoma
slow growing - resembles cells of stratum basale
Squamous cell carcinoma
highly atypical cells at all levels of epidermis
malignant melanoma
most serious - presents irregularly pigmented and multicolored lesions
Dermis consists of 2 layers
papillary layer - reticular layer
Papillary Layer
loose (areolar) connective tissue - have dermal papillae - projects into epidermis at the junction
Reticular Layer
dense irregular connective tissue - thicker than papillary but fewer cells -
Pacinian Corpuscles
large ovoid structures found in dermis & hypodermis - myelinated nerve ending within a concentric lamellae - detects pressure & vibration
Meissner Corpuscle
tapered cylindrical structures - located within dermal papillae of hairless - flattened schwann cells form lamellae - UNMYELINATED - detect light touch
Epidermal Skin Appendages
hair & follicles, eccrine, apocrine, sebaceous glands
Arrector Pili Muscle
smooth muscle extending from connective tissue of hair follicle to papillary layer of dermis - causes hair to stand on end upon contraction - insulation & sympathetic innervation
eccrine sweat gland
widely distributed, simple coiled tubular - thermoregulatory - excretes wastes and salts
eccrine sweat gland secretory portion
double layer of epithelial cells - lighter and larger than duct cells - located in the dermis or hypodermis
eccrine sweat gland duct portion
double layer of cuboidal - smaller and darker than secretory - leads to epidermal surface
Apocrine sweat glands
protein rich - secreted into hair follicles - merocrine secretion - coiled tubular - functional at puberty - bacterial breakdown of sweat leads to body odor -
apocrine secretory portion
very wide - simple cuboidal - eosiniophilic - found in hypodermis or dermis
apocrine duct portion
stratiied cuboidal - narrow lumen - empties into follicle canal
sebaceous oil glands
found everywhere besides thick skin (no hair follicles) - branched acinar - sebum lipid - secretes into hair follicle - holocrine secretion - acne causing
