M4 - Integument and Somatosensation Flashcards
Epidermis
Most superficial, 4-5 layers
Dermis
Thickest layer, 2 layers
Hypodermis
Composed of areolar and adipose CT
Fxns - protects underlying structures, stores energy, thermal insulation
Stratum corneum
Most superficial, dead keratinocytes, water resistance protection
Stratum granulosum
Living keratinocytes getting flattened, production of proteins, waterproofing
Stratum spinosum
Living keratinocytes, dendritic (langerhans) cells and melanocytes, trigger immune response + protect body from foreign substances, produce melanin, desmosomes help w pulling forces
Stratum lucidum
Dead keratinocytes, palms, finger tips, soles of feet, additional water barrier, thick skin
Stratum basale
Basal stem cells, cells divide to keratinocytes, tactile (Merkel) cells and melanocytes, produce melanin
Dermis
Vasculature, nerve fibers (tactile [touch] receptors, control blood flow + glandular secretion)
Dermis: papillary layer
Composed of areolar CT, dermal papillae and epidermal ridges interlock
Dermal papillae
Incr surface area for incr nutrient and gas exchange and waste secretion
Dermis: reticular layer
Mainly dense irregular CT, w bundles of collagen fibers, blood vessels, glands, hair follicles, nerves, cleavage (langer’s) lines
Cleavage (langer’s) lines
Collagen and elastin fiber organized in thin parallel bundles to resist stress, incisions perpendicular to lines heal more slow than parallel
Striae
Stretch marks
Keratinocytes
Most abundant cell, stores keratin, protection, bacteriostatic, waterproof skin, vitamin D synthesis, joined by desmosomes
Melanocytes
Melanin
Tactile (Merkel) cells
Mechanoreceptor, stimulating sensory nerves that brain perceives as touch, send afferent signal to sensory neuron, Merkel disc
Merkel disc
Merkel cell + sensory neuron
Epidermal dendritic (Langerhans cells)
Macrophages that engulf bacteria, foreign particles, and damaged cells and transport to nearby lymph nodes to begin immune response
Arrector pili muscles
Attach hair root
Sebaceous glands
Secrete oily sebum to soften and lubricate hair and skin
Somatosensation
Conveys body surface and interaction w environment, stimuli and sensation
Exteroceptors
Found in skin or mucous membranes
Interoceptors
Found in walls of viscera, detect stretching, O, temp, pressure
Proprioceptors
Found in muscles, tendons, jts, detect body and limb movement
Free nerve ending
Found in papillary layer of dermis and deep epidermis, pain, temp
Tactile (merkel) disc
Associated w tactile cells in stratum basale of epidermis, light touch
Root hair plexus
Surround hair follicles in dermis, movement of hairs - light touch
Unencapsulated tactile receptors
Free nerve ending, tactile (merkel) disc, root hair plexus
Encapsulated tactile receptors
Tactile (Meissner) corpuscles, lamellated (pacinian) corpuscles, bulbous (ruffini) corpuscles
Tactile (Meissner) corpuscles
In tips of dermal papillae, light touch, texture, shape, low frequency vibration
Lamellated (pacinian) corpuscles
In dermis, subcutaneous tissue, synovial membranes, and some viscera, deep pressure, high frequency, vibration, tickle
Bulbous (ruffini) corpuscles
In dermis and subcutaneous layer, continuous deep pressure, force/motion and skin distortion
Nevus
Mole
