Chapter5 Flashcards
(stores fat, anchors skin to underling structures) subcataneous tissue just deep to the skin is
hypodermis/superficial fascia
____: produce fibrous protein keratin; protective properties. Tightly connected by desmosomes, these cells arise from the deepest part of the epidermis from a cell layer called the stratum basale. These cells undergo almost continuous mitosis.
Keratinocytes
_____: 10-25% of cells in lower epidermis. These spider shaped cells produce pigment melanin; shields nucleus against UV radiation. Melanin granules accumulate on the superficial side of the keratinocyte nucleus.
Melanocytes
____: macrophages that help activate immune system. These star-shaped cells arise from bone marrow and migrate to the epidermis. Also called, Langerhans cells, they ingest foreign substances and are key activators of our immune system
Epidermal dendritic (Langerhans) cells
____: touch receptors. These cells are present at the epidermal-dermal junction. Shaped like a spiky hemisphere, each cell is associated with a disc-like sensory nerve ending.
Tactile (Merkel) cells
_____: of the dermis, is a thin superficial layer composed of areolar connective tissue.
Areolar connective tissue: collagen and elastic fibers and blood vessels. The looseness of this connective tissue allows phagocytes and other defensive cells to wanter freely as they patrol the area for bacteria that may have breeched the skin. Its superior surface is thrown into peglike projections called dermal papillae that indent the overlying epidermis.
Papillary layer
______: of papillary layer in dermis, contain:
Capillary loops- there for oxygen and carbon dioxide exchange.
Meissner’s corpuscles: touch receptors
Free nerve endings: pain receptors
Dermal papillae of papillary layer
______: ~80% of thickness of the dermis. Composed of dense irregular connective tissue.
Collagen fibers provide strength and resilience.
Elastic fibers provide stretch-recoil properties
reticular layer
_____: on the palms of hands and soles of the feet, these papillae lie atop larger mounds called dermal ridges, which in turn cause the overlying epidermis to form epidermal ridges. Epidermal ridges lie atop deeper dermal papillary ridges to form friction ridges of fingerprints. Collectively, these skin ridges increase friction and enhance the gripping ability. Also genetically determined.
Friction ridges
____: collagen fibers arranged in bundles form these lines. These lines run longitudinally in the skin of the head and limbs and in circular patterns around the neck and trunk. Incisions made parallel to these heal more readily.
Cleavage (tension) lines
Sweat (sudoriferous) glands: two types:
1._______: abundant on palms, soles, and forehead. Each is a simple, coiled, tubular gland. The secretory part lies coiled in the dermis, and the duct extends to open in a funnel-shaped pore at the skin surface. Commonly called sweat which is made of 99% water, NaCl, vitamin C, antibodies, dermcidin, & metabolic wastes. Functions in thermoregulation.
Eccrine (merocrine) sweat glands
Sweat (sudoriferous) glands: two types:
2. ______: confined to axillary and anogenital areas. Make sebum which is sweat + fatty substances and proteins. Their ducts empty into hair follicles. Functional from puberty onward, possibly as sexual scent glands. Contain two types of specialized glands.
Appocrine sweat glands
specialized apocrine sweat gland in external ear canal
ceruminous gland
specialized appocrine sweat gland secretes milk
mammary glands
also called sudoriferous glands, distributed over entire skin surface except nipples and parts of external genetailia
sweat glands
