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18 Cards in this Set

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  • Back
The skin is the body’s most massive organ.
It has two major components:
1. An ectoderm-derived layer of stratified squamous keratinized epithelium, the epidermis.
2. A mesoderm-derived layer of connective tissue underlying the epithelium and called the dermis.
the dermis does what ?
gives mechanical support, strength and thickness to the skin.
the epidermis is avascular or vascular? and is nourished by?
avascular...The epidermis lacks blood vessels, so it is nourished by diffusion of nutrients from capillaries in the dermis.
skin appendages
Hair
Nails
Cutaneous Glands
1. eccrine sweat glands
2. apocrine sweat glands
3. sebaceous glands
functions of the skin:
-resistance to ?, ?, ?
-protection from excess ?
-regulation of ?
-? perception
The skin is a self-repairing barrier against the outside world, and is involved in:
Resistance to abrasion
Resistance to infection
Resistance to dessication
Protection from excess UV light
Regulation of body temperature
Sensory perception
thick skin
-is found on ?
-thickness refers only to ? layer
-what is visible in thick skin?
This is found on the palmar surfaces of the hands and fingers and on the plantar surface of the feet and toes.
Thick and thin refers only to the thickness of the epidermal layer.
In thick skin a pattern of primary dermal ridges is visible.
Every primary ridge is subdivided into secondary dermal ridges by a downgrowth of the epidermis along its crest, an interpapillary peg. Projecting up from each secondary ridge are rows of dermal papillae.
layer of epidermis:
Stratum Germinativum
A single layer of low columnar cells that gives rise to new keratinocytes.
layer of epidermis:
stratum spinosum
Several layers of poly-hedral cells joined together by spine-like processes (prickle cells). Each spine is where a desmosome binds the two cells together.
layer of epidermis:
stratum granulosum
A few cells thick; cells contain basophilic soft keratin granules (keratohyaline granules).
layer of epidermis:
stratum lucidum
A thin transparent layer seldom seen in routine sections. Its tightly packed cells are dead, with nuclei undergoing lysis. The cell membrane envelops closely packed keratin filaments complexed with amorphous protein.
layer of epidermis:
stratum corneum
A compact layer of soft keratin at the surface; consists of cells in the form of flat scales lacking organelles and nuclei. Lipid released into the inter-cellular space makes for the highly waterproof properties of this layer.
psoriasis
This is the misregulated turnover of keratinocytes.
Mitosis occurs in the 3 deepest layers of the epithelium.
The overproduced keratinocytes take one week or less to reach the surface.
Stratum corneum hasn’t the time to form a strongly cohesive compact layer.
dermis
A superficial layer of loose connective tissue that merges with a deeper layer of dense irregular connective tissue.
The more superficial papillary layer is more vascular than the underlying reticular layer.
Dermis has numerous elastic fibers, scattered fibroblasts, macrophages & fat cells.
sudoriferous (sweat) glands
Thick skin has numerous eccrine sweat glands.
These are tubular glands whose secretory portions lie in the subcutaneous tissue.
The slightly helical duct takes the secretion (sweat) to the skin surface.
Most of the secretory cells are low columnar cells.
myoepithelial cells of the sudoriferous (sweat glands)
Myoepithelial cells are long, thin cells adapted for contraction, but representing modified epidermal cells.
They are arranged helically around the secretory portion between the secretory cells and their basement membrane.
Their contraction expels sweat from the gland.
sudoriferous sweat glands
-innervated by ?
-sweat is clear fluid of ?
The duct pursues a course through the dermis, enters an interpapillary peg and opens onto the crest of an epidermal ridge at a sweat pore.
Innervation is by cholinergic postganglionic sympathetic nerve fibers.
Sweat is clear fluid containing water, sodium, potassium, chloride, urea, lactic acid, and ammonia.
thin skin
-only what kind of dermis is thinner?
-the dermis is thinner/thicker?
-more or less sweat glands?
-possess appendages found/not found in thick skin?
Only the epidermis is thinner.
The dermis is actually thicker.
The total thickness of thin skin is then thicker than that of thick skin.
Friction ridges are absent, and there are fewer sweat glands.
Thin skin possesses appendages not found in thick skin.
thin skin
-stratum spinosum is thinner/thicker?
-stratum granulosum is distinct/indistinct?
-stratum lucidum is present/absent?
-stratum corneum is thick/thin?
-dermal papillae are more present/fewer in number, higher/lower, narrower or broader?
Stratum spinosum is much thinner.
Stratum granulosum is sometimes indistinct or discontinuous.
Stratum lucidum is absent.
Stratum corneum is not thick.
Dermal papillae are fewer, lower, and broader