Integ. System - Skin Flashcards
What are the two major components of the integumentary system?
Cutaneous membrane and accessory structures (hair, nails, exocrine glands)
What layers of the skin are part of the cutaneous membrane/integumentary system?
Epidermis- avascular epithelial tissue
Dermis- vascular connective tissue
What are the 3 exocrine glands involved in the integumentary system?
Sebaceous, ceruminous, and sudoriferous glands
What do sebaceous glands secrete?
Sebum (oil)
What do ceruminous glands secrete?
Cerumen (wax)
What do sudoriferous glands secrete?
Perspiration (sweat)
What are the two layers of the dermis and what are their ratios?
Papillary later (top 20%) Reticular layer (bottom 80%)
What does the papillary layer consist of?
Areolar tissue, small capillaries, lymphatics, sensory neurons
What does the reticular layer consist of?
Dense irregular connective tissue, collagen fibers, elastic fibers, large blood vessels, lymphatic vessels, nerve fibers, hair follicles, sebaceous glands, sudoriferous glands
What are other names for the hypodermis?
Subcutaneous
SubQ
Superficial fascia
What are the “mountains” of dermal papillae called?
Dermal papillae
What are the “valleys” of dermal papillae called?
Epidermal ridges
What kind of epithelium is the epidermis made of?
Keratinized stratified squamous epithelium
What are the four principal cell types in the epidermis?
Keratinocytes, melanocytes, langerhans cells, merkel cells (with their merkel disc neuron sub parts)
What protein do melanocytes produce?
Melanin
Eumelanin
Type of melanin that produces brown and black colors
Pheomelanin
Type of melanin that produces yellow and brown colors
Carotene
An orange-yellow pigment that normally accumulates in epidermal cells and adipose tissue
*Can be converted to vitamin A
Describe melanin’s production and travel
Melanocytes produce and package melanin into melanosomes.
Keratinocytes uptake the melanosomes, open them and release melanin to cytoplasm of the keratinocytes.
Keratinocytes
Most predominant epithelial cells in the dermis that produce keratin & lamellar granules
What is found inside keratinocytes?
Keratin intermediate filaments
*Not yet fully formed keratin
Lamellar granules
Specialized organelles found in keratinocytes in the stratum spinosum
What are the five layers of strata from deepest to most superficial?
Basale, Spinosum, Granulosum, Lucidum, Corneum
How many layers of cells make up the stratum basale?
One layer of cuboidal or columnar keratinocytes bound to basement membrane by hemidesmosomes
What are the dividing cells undergoing mitosis in the stratum basale called?
Basale (germinative) cells
*Divide horizontally and vertically. Oldest cells are most superficial
What are the specialized cells of the stratum basale?
Merkel cells (and merkel discs) and melanocytes
What is the keratin status in the stratum basale?
Sparse keratin intermediate fibers in cytoplasm
How many layers of keratinocytes make up the stratum spinosum?
8-10 layers bound by desmosomes
What cells make up the stratum spinosum?
The old cells that are pushed up after mitosis from the stratum basale
What are the specialized cells found in the stratum spinosum?
Langerhans cells (Responsible for immunity)
Lamellar granules
What is the keratin status of the stratum spinosum?
Keratinocytes produce coarse bundles of keratin intermediates
How many layers of cells make up the stratum granulosum?
3-5 layers of keratinocytes that begin apoptosis and stop producing keratin
What are the specialized cells in the stratum granulosum?
Keratohyalin granules and lamellar bodies
What do keratohyalin granules do?
Release proteins that bind keratin intermediates into thick keratin bundles
What do lamellar bodies do?
Release a lipid mixture that attaches the cell envelope to more superficial cells
Cell envelope
A collection of layers of proteins on the inner leaflet of plasma membranes that thickens the membrane
How many cell layers make up the stratum lucidum?
4-6 layers
*Only present in thick skin
Describe the cells of the stratum lucidum.
Cells are clear, flat, and dead with large amounts of keratin and a cell envelope.
How many cell layers are in the stratum corneum?
15-50+ layers of dead/flat keratinocytes containing keratin.
Keratinization
The formation of a layer of dead, protective cells filled with keratin
*Occurs on all exposed skin surfaces except the eyes
How long is the skin life cycle?
It takes 4-6 weeks for a cell to move from stratum basale to stratum corneum and ultimately shed
Where is thin skin located?
Hairy skin
*Except for lips and external genitalia
Is the dermis thicker in thin or thick skin?
Thin skin
What glands are found in thin skin?
Sebaceous glands, merocrine sweat glands, apocrine sweat glands
Where is thick skin found?
Fingertips, toes, soles of feet, palms of hands
What glands are found in thick skin?
Only merocrine sweat glands
Are epidermal ridges found in thin or thick skin?
Thick skin
How do melanocytes affect skin pigmentation?
All races have same number of melanocytes, but their activity level and type of melanin produced will vary
What two factors are involved in skin coloration?
Epidermal pigmentation and dermal circulation
Skin turgor
Properties of flexibility and resilience, indicating a hydrated or dehydrated state
Lines of cleavage (tension lines)
Collagen and elastic fibers in the dermis arranged in parallel bundles that resist force in a specific direction
Plexus
A network of blood vessels or nerves
Subpapillary plexus
Blood vessels in the papillary layer that give rise to capillary loops
Cutaneous plexus
Blood vessels in the hypodermis layer that branch into the reticular layer of the dermis
What do the nerve fibers (neurons) in the skin control?
Blood flow and gland secretions
What do the sensory receptors (nerve endings) in the skin do?
Provide cutaneous sensations
What sensation do merkel cells and their discs detect?
Steady, light pressure
What sensation do tactile corpuscles detect?
Light rubbing
What sensation do bulbous corpuscles detect?
Steady pressure and stretching
What sensations do free nerve endings detect?
Temperature, touch, pain, pressure
What sensations do lamellated corpuscles detect?
Deep pressure and vibration
What are the functions of the integumentary system?
Thermoregulation, blood reservoir, protection, cutaneous sensation, excretion and absorption, synthesis of vitamin D
How does the integumentary system provide protection?
Keratin- protects underlying tissues from microbes, abrasion, heat, chemicals
Lipids- inhibit evaporation
Sebum- moisture for hair/nails, contains bactericidal chemicals
Acid pH- retards growth of microbes; acidic mantle of skin
Melanin- UV protection
Langerhans cells- immunity; phagocytizes microbes
What do arteries do?
Move blood away from the heart
*Drawn in red
What do veins do?
Move blood to the heart
*Drawn in blue
What do capillaries do?
Site of exchange between veins and arteries
What are sebaceous glands?
Exocrine glands in the skin that secrete sebum through holocrine mode of secretion
Sebum
A mixture of triglycerides, cholesterol, proteins, and electrolytes
What are sudoriferous glands?
Exocrine glands in the skin that secrete sweat through merocrine mode of secretion
Where are apocrine sweat glands found?
Armpit, nipples, pubic/groin region
What is the sweat produced by apocrine sweat glands like?
Where does it secrete?
Sticky, cloudy, potentially smelly
Secreted into hair follicle
What is the secretory activity of apocrine sweat glands controlled by?
Nervous system and hormones
What is the sweat produced by merocrine sweat glands like?
Where does it secrete?
Watery secretions of water, salt, organic compounds
Secreted directly onto skin surface
What are the functions of merocrine sweat glands?
Cool the skin, excrete water/electrolytes, flush microorganisms and harmful chemicals from skin
Insensible perspiration
Interstitial fluid lost by evaporation through the stratum corneum
*From burns, blisters, hypertonic solution immersion
Sensible perspiration
Water excreted by sweat glands
What are the effects of aging?
Epidermal thinning Decreased langerhans cells Decreased vitamin D3 production Decreased melanocyte activity Decreased glandular activity Loss of subcutaneous fat
