Week 2 - Integumentary System - Marisa Flashcards
organs of the integumentary system include
skin and its accessory structures: hair, nails, glands, blood vessels, muscles & nerves
dermatology
medical specialty for the diagnosis and treatment of disorders of integumentary system
what is the largest organ of the body
cutaneous membrane (skin)
what is the difference between the epidermis and dermis
EPIDERMIS: outer, thinner, 5 layers. Composed of epithelial cells, is the outermost protective shield of the body. Non-vascularized; therefore nutrients reach the epidermis by diffusing through the tissue fluid from blood vessels in the dermis. DERMIS: inner, thicker, 2 layers. Makes up the bulk of the skin, is a tough, leathery layer composed mostly of fibrous connective tissue. Vascularized.
what is the layer beneath the dermis called & what is its function
Hyopdermis or subcutaneous layer. It anchors skin to the underlying tissues and organs, stores fat, acts as a shock absorber, and acts as an insulator to reduce heat loss. It also contains lamellated corpuscles which detect external pressure applied to the skin.
what is the epithelium epidermis composed of
keratinized stratified squamous epithelium. Consists of 4 distinct cell types and 4-5 distinct layers
what are the four types of cells in the epidermis?
- keratinocytes 2. langerhans cells (dendritic) 3. melanocytes 4. merkel cells (tactile)
what do keratinocytes produce and what is their function
- keratin; the fibrous protein that helps give the epidermis its protective proterties. 2. lamellar granules; release water and acts as a repellant or sealant
keratinocytes
tightly connected to one another by desmosomes, arise in the deepest part of the epidermis. These cells undergo constant mitosis and are pushed upwards by the production of new cells below them, causing millions of keratinocytes to rub off every day giving us a totally new epidermis every 25 to 45 days.
what do melanocytes produce and what is their function
melanin; protects against UV radiation
90% of epidermis cells are
keratinocytes
what is another name for langerhans cells and why
dendritic cells or intraedpidermal macrophage cells.They arise from bone marrow and migrate to the epidermis where they ingest foreign substances and are key activators of our immune system
what is another name for merkel cells and what is their function
tactile epithelial cells; every tactile cell is intimately associated with a disclike sensory nerve ending and therefore functions as a sensory receptor for touch
how many layers compose the epidermis
5; 4 thin skin layers and 1 thick skin layer
the layer of thick skin of the epidermis is called
stratum lucidum; ie: tinger tips, palms, soles of feet
what is the layer of the epidermis that is composed mostly of keratinocytes
stratum spinosum
what is the layer of the epidermis that includes keratohyalin and lamellar granules
stratum granulosum
what is the epidermis layer where cell division occurs & therefore produces all other layers
stratum basale aka stratum germinativum
what is the most superficial layer of the epidermis
stratum corneum
what is the deepest epidermis layer
stratum basale aka stratum germinatiuvum
what is the stratum corneum composed of
many flat sublayers of dead keratinocytes called corneocytes or squames
corneum means
dead skin cells
how is a callus formed
through constant friction of the stratum corneum
list the order of the epidermis layers from superficial to deep
stratum corneum, startum lucidum (only on thick skin), stratum granulosum, stratum spinosum, stratum basale
keratinization
the accumulation of more and more protective keratin, occurs as cells move from the deepest layer to the surface
what is the skin structure that thickens heavily when one gains weight?
hypodermis
what is the layer of the epidermis that appears to be absent in thin skin
stratum lucidum
in what layer of the epidermis do keratinocytes appear to have prickly spines
stratum spinosum
what is the function of keratohyalin and lamellar granules
keratohyalin helps form keratin in the upper layers, lamellar granules contain a water-resistent glycolipid that is spewed into the extracellular space and is a major factor in slowing water loss across the epidermis
what is the dermis composed of
connective tissue containing collagen and elastic fibers2 layers: papillary layer and reticular layer
which layer of the dermis is thin and superficial
papillary layer
dermal papillae
contain capillary loops & house free nerve endings (pain receptors) and touch receptors called tactile or meissner’s corpuscles
which layer of the dermis consists of dense connective tissue containing thin collagen and elastic fibers, dermal papillae, corpuscles of touch, and free nerve endings?
papillary layer
which layer of the dermis consists of dense irregular connective tissue containing collagen and elastic fibers which provide strength, extensibility, and elasticity to the skin, adipose cells, hair follicles, nerves, sebaceous glands, and sweat glands?
reticular layer
what layer of the dermis accounds for about 80% of the thickness of it
reticular layer
what are tension lines
aka cleavage lines; indicate the predominant direction of underlying collagen fibers
what layer of the dermis can tension lines be found in
reticular layer
epidermal ridges
refelct contours of the underlying dermal papillae and form the basis for fingerprints/footprints. Their function is to increase firmness of grip by increasing friction
what are the three pigments that contribute to skin color
melanin, carotene, and hemoglobin
what happens when we expose our skin to sunlight
keratinocytes secrete chemicals that stimulate melanocytes causing melanin to build up in order to protect our skin cells from UV radiation by absorbing rays and dissipating the energy as heat.
what color is melanin pigment
reddish yellow to brownish black
what color pigment is carotene
yellow to orange
where is melanin mostly located
in the epidermis
where is carotene mostly located
in the stratum corneum, dermis, and subcutaneous layer
albinism
an inherited inability to produce melanin
vitiligo
a condition in which there is a partial or complete loss of melanocytes
where is hemoglobin mostly located
in erythrocytes flowing through dermal capillaries
what are the primary functions of hair (pili)
protection, reduction of heat loss, and sensing light touch
what is hair composed of
dead, keratinized epidermal cells
each hair consists of:
- shaft, which mostly projects above the surface of the skin. 2. root, which penetrates into the dermis. 3. hair follicle, which surrounds the root and consists of an epithelial root sheath which in turn is surrounded by a dermal root sheath
what is located at the base of a hair follicle
the bulb
what is the indentation on the hair follicle where blood vessels provide nourishment to the growing hair
papilla of the hair
where does cell division of the hair occur
in the hair matrix of the bulb
what is the growth cycle of hair
growth stage, regression stage, resting stage
hair root plexus
a knot of sensory nerve endings which wraps around each hair bulb
the color of one’s hair is determined by what
the amount and type of melanin
what are the different types of hairs
lanugo, vellus hairs (the pale, fine body hair of children and adult females) , terminal hairs (coarser, longer hair of the eyebrows and scalp)
what are nails composed of
hard, keratinized epidermal cells located over the dorsal surfaces of the ends of fingers and toes
each nail consists of:
- a free edge 2. a transparent nail body (plate) with a whitish lunula at its proximal end 3. a nail root embedded in a fold of skin
hyponychium
nail bed (located under free edge of nail) attaches nail to the fingertip
eponychium
(cuticle) attaches the margin of nail wall to neighboring epidermis
nail matrix
the thickened proximal portion of the nail bed, responsible for nail growth
where are sebaceous glands found
typically connected to hair follicles all over the body except in the thick skin of the palms and soles
what is the function of sebaceous glands
to secrete an oily substance - sebum, which prevents dehydration of hair and skin, and inhibits growth of certain bacteria
where and what are sudoriferous glands
sweat glands (produce perspiration), which are distributed over the entire skin surface except the nipples and parts of the external genitalia.
what are the two types of sudiferous glands
eccrine & apocrine
eccrine sweat glands
(merocrine glands) which have an excretory duct that opens at a pore at the surface of the epidermis; the sweat is secreted by these glands. they help to cool the body by evaporating, eliminate small amounts of waste, responsible for emotional sweating or cold sweat.
apocrine sweat glands
located mainly on the skin of the axilla, groin, areolae, and bearded facial regions of adult males; their excretory ducts open into hair follicles
when is apocrine sweat secreted
during emotional stress and sexual excitement
myoepitheliocytes
help squeeze out secretions into their hair follicles
ceruminous glands
modified sweat glands located in the ear canal; along with nearby sebaceous glands. They are involved in producing a waxy secretion called cerumen (earwax), which provides a sticky barrier that prevents entry of foreign bodies into the ear canal.
where is thin (hairy) skin found on the body
on all body regions except the palms, palmar surfaces of digits, and soles
where is thick (hairless) skin found on the body
covers the palms, palmar surfaces of digits, and soles
what are the functions of the skin
- thermoregulation 2. blood reservoir 3. protection 4. cutaneous sensations 5. excretion and absorbtion 6. synthesis of vitamin D
where does the dermis receive its blood from
- branches of arteries supplying skeletal muscles 2. arteries that supply the skin directly, including: cutaneous plexus and papillary plexus
venous plexus
drains blood from the dermis into larger subcutaneous veins
development of the integumentary system
the epidermis develops from the ectoderm; nails, hair, skin = epidermal derivatives. The epidermis of a fetus is protected by a fatty substance called vernix caseosa. The dermis developes from the mesoderm
what are some effects of aging people begin to see in their late forties
wrinkling, decrease of skin’s immune responsiveness, dehydration and cracking of skin, decreased sweat production, decreased numbers of functional melanocytes resulting in gray hair and atopical skin pigmentation, loss of subcutaneous fat, general decrease in skin thickness, and an increased susceptibility to pathological conditions
what are some effects of aging that occur during the second and third decades of life
decrease in growth of hair and nails, brittle nails
which epidermal cell type is most numerous
keratinocyte
which cell functions as part of the immune system
dendritic cells
the epidermis provides a physical barrier due largely to the presence of:
keratin
skin color is determined by
the amount of blood, pigments, and oxygenated level of the blood
the sensations of touch and pressure are picked up by receptors located in
the dermis
skin surface markings that reflect points of tight dermal attachment to underlying tissues are called
flexure lines
an arrector pili muscle can_
cause a hair to stand up straight
the product of this type of sweat gland includes protein and lipid substances that become odoriferous as a result of bacterial action
apocrine gland
