Human Anatomy by McKinley Ch. 5
Terms
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- integument
- the skin that covers your body, also known as the cutaneous membrane
- integumentary system
- consists of skin and derivatives-nails, hair, sweat glands, and sebaceous glands
- dermatology
- scientific study and treatment of integumentary system
- integument has two separate layers
- a kater of stratified squamous epithelium called epidermis, and a deeper layer of dense irregular connective tissue called dermis
- subcutaneous layer (hypodermis)
- deep to the dermis, layer of areolar and adipose connective tissue (not part of ingeumentary system)
- skin is selectively permeable
- some materials are able to pass through the skin and others are effectively blocked
- transepidermal water loss (TEWL)
- some interstitial fluids slowly penetrate the epidermis to the surface, where they evaporate
- insensible perspiration
- release of water vapor from sweat glands under "normal" circumstances when we are not sweating
- epidermal dendritic (Langerhans) cells
- immune cells (phagocytic) in the skin
- tactile (Merkel) cells
- large, specialized epithelial cells that stimulate specific sensory nerve endings when distorted by fine touch or pressure
- sensible sweating
- occurs when the body needs to cool itself off
- sebum
- from sebaceous glands that lubricates the skin surface and hair
- urea
- nitrogenous waste product of body cells
- epidermis
- keratinized, stratified squamous epithelium
- stratum basale
- deepest epidermal layer, tightly attached to underlying basement membrane that separates the epidermis from connective tissue of adjacent dermis
- keratinocytes
- stem cells that provide new epidermal cells to replace superficial dead ones
- melanocytes
- transfer pigment granules into keratinocytes in basal layers
- straum spinosum
- just above stratum basale, nondividing, highly specialized keratinocyte
- stratum granulosum
- keratinization begins, upper layer
- stratum lucidum
- thin, translucent, superficial to granulosum, only in thick skin, filled with protein eleiden (intermediate keratin)
- stratum corneum
- most superficial layer of epidermis, 20-30 layers of dead, scaly, keratinized cells
- How is skin classified
- thick or thin based on number of strata in epidermis and relative thickness of epidermis
- thin epidermis
- lacks stratum lucidum, has hair follicles, sebaceous glands, and sweat glands
- thick epidermis
- all five epidermal strata, has sweat glands
- nevus
- commonly called a mole
- freckles
- yellowish or brown spots of excessive melanocyte activity
- hemangioma
- congenital anomaly that results in skin discoloration due to blood vessels that proliferate and form a benign tumor "strawberry birthmark"
- friction ridge
- fingerprints, toeprints, and palms
- dermis
- lies deep to the epidermis, connective tissue layer
- papillary layer
- external region of dermis directly adjacent to epidermis, dermal papillae and epidermal ridges interlock
- reticular layer
- deeper, major portion of the dermis, surrounds structures, fibrous network
- striae
- stretch marks, skin stretches past capabilities and collagen fibers tear
- lines of cleavage
- identify the predominant orientation of collagen fiber bundles
- vasoconstriction
- blood vessels narrow when we are cold, blood must flow deeper to conserve heat away from periphery of body
- vasodilation
- blood vessels dialate, goes to superficial vessels and heat can more easily dissapate through skin, decrease in circulation to other organs
- layers of integument
- see table 5.2 on page 131
- free edge
- whitish layer of nail
- nail body
- pinkish part of nail
- nail plate
- free edge, body and root
- nail matrix
- actively growing part of nail
- lunula
- whitish, semiluminar area of the prosimal end of the nail body
- pilus
- a single hair
- lanugo
- fine, unpigmented downy hair that first appears on the fetus in the last trimester
- vellus
- most of the lanugo has been replaced by birth by similarly fine, unpigmented or lightly pigmented hair
- terminal hair
- coarser, pigmented, and longer than vellus, grows on scalp, eyebrows, and eyelashes, pubic hair
- connective tissue root sheath
- originates from the dermis
- epithelial root sheath
- originiates from epidermis
- arrector pili muscle
- stimulated in response to an emotional state like fear, exposure to cold temperatures, "goose bumps" or hair standing on end
- pheromones
- chemical signals involved in attracting members of the opposite sex
- alopecia
- thinning of the hair
- sweat gland duct
- carries sweat to the surface
- myoepithelial cells
- in response to sympathetic nervous stimulation, contract to squeeze gland to disharge accumulated secretion
- merocrine sweat glands
- most numerous, makes sweat
- apocrine sweat glands
- coiled, tubular glands that release into hair follicles at armpit, nipples, groin, and anus
- exocytosis
- process by which sweat glands excrete
- sebaceous glands
- secrete oily, waxy to protect hair, bactericidal properties
- ceruminous glands
- modified sweat glands located only in the external ear canal to form earwax (cerumen)
- mammary glands
- modified apocrine sweat glands, become functional only in pregnant females
- integumentary system components not reparied after damange
- hair follicles, glands, nerves, and muscle cells
- ectoderm
- gives rise to epidermis
- mesoderm
- gives rise to dermis
- vernix caseosa
- sloughed off periderm mixed with sebum to create a protective coating for fetus' skin