integumentary system Flashcards
layers of the epidermis from outer to innermost:
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1. stratum corneum - outermost hydrophobic layer
2. stratum lucidium - only present in palms of hands and soles of feet
3. stratum granulosum - skin cells lose organelles here, begin dying, and are filled with keratin
4. stratun spinosum - provides skin strength/flexibility; held together by desmosomes
5. stratum basale (germinativium) - deepest layer of epidermis where new skin cells are formed
dermis
second layer of skin and highly vascularized. it is connected to the epidermis above via the basement membrane
epidermal cells
- melanocytes
- merkel cells
- keratinocytes
- langerhans cells
melanocytes
transfers skin pigment melanin to keratinocytes
merkel cells
attach to sensory neurons and functions in touch sensation
keratinocytes
produce keratin
help waterproof
langerhans cells
interact with immune cells
papillary region
- vascular network within upward projecting papillae that helps supply nutrients to epidermis and regulates temperature
- papillae contain Meisner’s corpuscles (sensory touch receptors)
hypodermis (subcutaneous)
- consists of areolar and adipose tissue
- functions in fat storage, heat insulation, and shock absorption
- contains pressure sensing nerve ending and passage for blood vessels
reticular region
region with dense connective tissue, collagen, and elastic fibers; packed with glands, sweat gland ducts, fat, and hair follicles
order of skin
- epidermis
- dermis
- papillary dermis
- reticular dermis
- hypodermis
thermoregulation in skin
- aids in regulating body temperature
- capillaries dilate to release heat, and constrict to preserve heat
- goosebumps (piloerection reflex) occurs when cold, elevates hairs to trap heat
environmental sensory input
nerve endings in skin convey temp, pressure, pain, and touch
vitamin D synthesis
UV radiation activates skin molecules to synthesize vitamin D
eccrine glands
- opens directly to skin, located on majority of skin
- regulates temperature through perspiration and urea elimination