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41 Cards in this Set

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  • Back
what does the epidermis consist of?
keratinized stratified squamous epithelium
is the epidermis vascular or avascular?
avascular; therefore, it relies on nutrients and oxygen from diffusion from capillaries within the dermis
where are the cells in the epidermis with the highest metabolic demand?
closest to the dermis because the epidermis is avascular
what are the 4 types of cells of the epidermis?
1. keratinocytes
2. melanocytes
3. langerhans (dendritic)
4. merkel cells
which cell type dominates the epidermis?
keratinocytes
what are keratinocytes?
they're the most abundant cell in the epidermis
- form several layers (strata)
- continuously produced by stem cell division in deepest layers
- shed at the exposed surface
how are keratinocytes produced?
by stem cell divisions in deepest layers
what are melanocytes?
they produce melanin- involved in skin coloration
- located in stratum basale
- protect against UV radiation because the melanosomes are concentrated around the nucleus
what two substances are involved in skin coloration?
melanin and carotene
what are langerhans cells?
also called dendritic cells
- they participate in the immune response by stimulating a defense
what do langerhan cells create a defense against?
- microorganism that manage to penetrate the superficial layers of the epidermis
- superficial skin cancers
what are merkel cells?
-sensitive to touch due to tactile discs
-release chemicals that stimulate sensory nerve endings
-scattered among the basal cells
what are the 5 epidermal layers from deepest to superficial?
1. stratum basal
2. stratum spinosum
3. stratum granulosum
4. stratum lucidum
5. stratum corneum
what is the stratum basale?
-its the deepest layer
-consists of single row cuboidal or columnar keratinocytes
-stem cells- basal cells- dominate this layer
-keratinocyte cytoskeleton
- melanocytes and merkel cells are scattered among the basal cells
what are basal cells?
they dominate the stratum basale; they are stem cells whose divisions replace the more superficial keratinocytes that are lost or shed at the epithelial surface
what is the keratinocyte cytoskeleton?
-tinofilaments: keratin
-attachment to desmosomes; hemidesmosomes- attach the cells of this layer (stratum basale) to the basal lamina
what is the stratum spinosum?
-8-10 layers of multiple-sided keratinocytes bound together by desmosomes
-include dendritic cells, langerhans cells, and melanocytes
-tonofilaments: desmosomes that bind the layers of keratinocytes
what are dendritic cells?
stimulate defense against microorganisms and superficial skin cancers
what is the stratum granulosum?
-3-5 layers of flattened keratinocytes
- its the transition layer between metabolically active strata and dead cells
what do the layers in the stratum granulosum consist of?
-apoptosis
-keratohyalin
-lamellar granules
what happens once the cells reach the stratum granulosum?
by the time the cells have reached this layer most have stopped dividing and started making large amounts of keratin and keratohyalin
what is the stratum lucidum?
-it separates the stratum corneum from deeper layers
-its only in the think skin
-3-5 layers flattened and clear filled with dead keratinocytes
why are the keratinocytes in the stratum lucidum dead?
because they're undergoing dehydration causing thickened plasma membranes; keratin
what is the stratum corneum?
-25-30 layers flattened, filled with dead keratinocytes that are tightly interconnected by desmosomes
- they continuously shed
-cell interior is mostly keratin; interstitial lipids
-callus
what does the dermis consist of?
-a papillary layer of areolar tissue and a reticular layer of dense irregular CT
-blood vessels, nerves, glands, and hair follicles
explain the CT in the dermis:
strong connective tissue consisting of collagen and elastic fibers; includes fibroblasts, macrophages, and adipocytes
what is the papillary region of the dermis?
-consists of areolar CT
-nourishes and supports the epidermis
-includes dermal papillae
what is the dermal papillae?
-in the papillary region, consists of capillary loops, meissner corpuscles, free nerve endings, epidermal ridges, and is sensitive to light touch
what is the reticular region of the dermis?
-consists of dense irregular CT
-restricts spread of pathogens, stores lipid reserves, attaches skin to deeper tissues, thermoregulations due to blood vessels
-adipose cells, hair follicles, nerves, sebaceous glands, sudoriferous glands, sensitive to deep pressure and vibration
what are the three accessory structures of the skin?
1. hair
2. exocrine glands
3. nails
what is hair?
produce hairs that protect the skull and provide delicate touch sensations on general body surface
what are exocrine glands?
assist in thermoregulation, excrete wastes, and lubricate epidermis
what are the three types of exocrine glands?
1. sebaceous glands
2. sudoriferous glands
3. ceruminous glands
what are sebaceous glands?
oil glands that discharge oily lipid secretion called sebum that coats the hair shaft and surrounding epidermal surfaces
what are sudoriferous glands and the two types?
sweat glands
1. apocrine
2. merocrine
what are apocrine sweat glands?
founds in armpits, around nipples, and pubic region; produce sticky, cloudly, and sometimes odorous secretion
what are merocrine sweat glands?
they discharge secretions onto surface of the skin
what do nails do?
they support and protect tops of fingers and toes
what is thermoregulation?
maintenance of normal body temp through either insulation or evaporate cooling
what are the seven main functions of integument?
1. thermoregulation
2. blood reservoir
3. protection
4. cutaneous sensations
5. excretion
6. ansorption
7. synthesis of vitamin D
what are cutaneous sensations?
detection of touch, pressure, pain, and temperature stimuli, and the relaying of that information to the nervous system