The organs of the integumentary system include
are what?
the skin and its accessory structures including hair, nails, and glands, as well as blood vessels, muscles and nerves
Dermatology is what?
The medical specialty for the diagnosis and treatment of disorders of the integumentary system.
Clinical term for "skin"
cutaneous membrane
Where is skin the thickest?
The heels
Where is skin the thinnest?
The eyelids.
Outer, thinner layer of skin is called ?
The epidermis
What is the Epidermis made of?
epithelial tissue
What is the "dermis"?
inner, thicker layer of skin
What lies beneath the dermis?
A subcutaneous (subQ) layer (also called hypodermis) which attaches the skin to the underlying tissues and organs.
What is the epidermis made of?
The epidermis is composed of keratinized stratified squamous epithelium
What are the 4 major types of cells in the epidermis?
Keratinocytes
Melanocytes
Langerhans
Merkel
What do Merkel cells do?
function in the sensation of touch along with the adjacent tactile discs
What do Langerhans cells do?
involved in immune responses, arise from red bone marrow
What do Melanocytes do?
produce the pigment melanin that protects against damage by ultraviolet radiation
What do Keratinocytes do?
(90% of the cells) produce keratin which is a tough fibrous protein that provides protection
I.D. the cell
Keratinocytes
ID the cell
Langerhans
ID the cell
Melanocytes
ID the cell
Merkel
Review
List the layers of the epidermis.
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
composed of many sublayers of flat, dead keratinocytes called that are continuously shed and replaced by cells from deeper strata; constant friction can stimulate formation of a callus.
Stratum corneum
where continuous cell division occurs which produces all the other layers
Stratum basale
8-10 layers of keratinocytes
Stratum spinosum
comprised of keratinocytes with lamellar granules
Stratum granulosum
present only in thick skin (the skin of the fingertips, palms, and soles)
Stratum lucidum
What is Keratinization?
The accumulation of more and more protective keratin, occurs as cells move from the deepest layer to the surface layer
ID the Layers Top to Bottom.
•Stratum corneum
•Stratum lucidum
•Stratum granulosum
•Stratum spinosum
•Stratum basale
Stratum Basale
•Deepest single layer of cells
•Called stratum germinativum
•Combination of merkel cells, melanocytes, keratinocytes &
stem cells that divide repeatedly
•Cells attached to each other & to
basement membrane by desmosomes & hemidesmosomes
Stratum Spinosum
•8 to 10 cell layers held together by desmosomes
•During slide preparation, cells shrink
and look spiny
•Melanin taken in by phagocytosis from
nearby melanocytes
Stratum Granulosum
•3 - 5 layers of flat dying cells
•Show nuclear degeneration
•Contain dark-staining granules
•Contain lamellar granules that release
lipid that repels water
Stratum Lucidum
•Seen in thick skin on palms & soles
of feet
•Three to five layers of clear, flat,
dead cells
•Contains precursor of keratin
Stratum Corneum
•25 to 30 layers of flat dead cells
filled with keratin and surrounded by lipids
•Continuously shed
•Barrier to light, heat, water,
chemicals & bacteria
•Friction stimulates callus formation
What produces keratinocytes?
Stem cells divide to produce keratinocytes
This is composed of connective tissue containing collagen and elastic fibers
Dermis
What are the 2 layers of the dermis?
•the outer papillary region consists of areolar connective tissue containing thin collagen and elastic fibers, dermal papillae, corpuscles of touch and free nerve endings
•The deeper reticular region consists of dense irregular connective tissue containing collagen and elastic fibers adipose cells, hair follicles, nerves, sebaceous (oil) glands, and sudoriferous (sweat) glands
can appear if the skin is stretched too
much
Striae or stretch marks
Finger like projections called dermal
papillae create fingerpints.
What are the functions of the papillary region?
–anchors epidermis to dermis
–contains capillaries that feed
epidermis
–contains Meissner’s
corpuscles (touch) & free nerve endings (pain and temperature)
•Provides strength, extensibility &
elasticity to skin
–stretch marks are dermal tears from
extreme stretching
Reticular Region of the dermis
What do Epidermal ridges do?
reflect contours of the underlying dermal papillae and form the basis for fingerprints (and footprints); their function is to increase firmness of grip by increasing friction.
Variations in skin color arise from variations in the amounts of three pigments:
melanin, carotene, and hemoglobin
Where is Melanin located and how is it produced?-
produced by melanocytes (located
mostly in the epidermis, where it absorbs UV radiation)
Why are people different colors?
differences in skin color is due to the amount of pigment produced
What is Carotene?
Hemoglobin - red color (located in erythrocytes
yellow-orange pigment (found in the stratum corneum, dermis, and subcutaneous layer)
is not part of the skin but, among its
functions, it attaches the skin to the underlying tissues and organs
Subcutaneous (subQ) layer
contains lamellated (pacinian) corpuscles which
detect external pressure applied to the skin.
Subcutaneous Layer
Hair is composed of what?
dead, keratinized epidermal cells
What are the parts of the pillie (hair)?
•root which penetrates into the dermis
•hair follicle
•epithelial root sheath
•dermal root sheath
What are the functions of hair?
•Prevents heat loss
•Decreases sunburn
•Eyelashes help protect eyes
•Touch receptors (hair root plexus)
senses light touch
Name the glands of the skin.
•Sebaceous (oil) glands
•Sudoriferous (sweat)
glands
•Ceruminous (wax)
glands
•Mammary (milk) glands
Sebum does what?
–combination of cholesterol, proteins,
fats & salts
–keeps hair and skin soft & pliable
–inhibits growth of bacteria &
fungi(ringworm)
What are the 2 types of sweat glands?
Eccrine
Apocrine
These are found in most areas of skin contain a secretory portion in dermis with duct to surface and regulate body temperature with perspiration
Eccrine (sweat) glands
These are found in the armpit and pubic region contain secretory portion in dermis with duct that opens onto hair follicle and secretions more viscous
Apocrine (sweat) glands
Where would you find Ceruminous Glands?
The ear.
What are nails?
Tightly packed, keratinized cells
ID the more prominent features from L-R
Nail Root
Cuticile
Luluna
Nail Bed
Free Edge
Nail Matrix
What are the general functions of skin?
•Regulation of body temperature
•Protection as physical barrier
•Sensory receptors
•Excretion and absorption
•Synthesis of vitamin D
How does skin aid in thermoregulation?
•Releasing of sweat onto the skin
Adjusting flow of blood to the body
surface
Shivering and constriction of surface
vessels
How does the skin provide protection?
–tight cell junctions prevent bacterial
invasion
–lipids released retard evaporation
–pigment protects somewhat against UV
light
–langerhans cells
alert immune system
True or False?
Lipid soluble substances can be absorbed through the skin
