Skin. Consists of the Epidermis and the Dermis. Keratinized-stratified-squamous-epithelium (epidermis) firmly attached to a thick layer of DI CT (Dermis).
Superficial Epithelium, (epi-, above) uppermost layer. Composed of dead-strat-squam cells. Prevents dessication and the entry of Pathogens. Avascular, but innervated.
Deep to the Epidermis. Extensively vascular inner layer of the skin. Can be broken down into the Papillary and Reticular layers
Deep to the Dermis (AKA Superficial Fascia or Subcutaneous Layer). Composed of LCT that separates the integument from the deep fascia around other organs
PROTECTION of underlying tissues and organs against impact, dessication and chemicals. EXCRETION, MAINTENANCE of homeostasis. PRODUCTION of Melanin, keratin and Vitamin D₃, STORAGE of lipids and DETECTION of stimuli
Most abundant epithelial cells. Contain large amounts of Keratin.
Fibrous protein found in the epidermis, hair, and nails. Makes those structures tough and water-resistant; precursor is keratohyalin
Produced by melanocytes and found primarily in the S.Basale. When UV Light hits the skin it is absorbed by the melanin. Individual pigments are determined by the rate that melanin is metabolized.
A Steroid that is converted to calcitriol, a hormone important to normal calcium metabolism.
Covers most of the body surfaces, contains four Strata of keratinocytes and is about as thin as the wall of a plastic sandwich bag
Occurs on the palms of the hands and the soles of the feet. Contains a fifth strata, the Stratum Lucidum. It also has a much thicker superficial layer, the statum corneum (callouses)
Stratum Basale, Stratum Spinosum, Stratum Granulosum, Stratum Lucidum, Stratum Corneum
The deepest epidermal layer (AKA Stratum Germinativum). Single layer. Hemidesmosomes attach the cells to the basement membrane. This layer is dominated by Basal cells; Stem cells whose rapid division replace the superficial cells. They form ridges adjacent to the dermal papillae.
(singular papilla); a nipple-shaped mound that project into the epidermis. The papiallaes formation with the ridges are significant due to the strength their structure gives.
Superficial to the S.Basale, where daughter cells are received after each mitotic cycle. Consists of 8 to 10 Layers of cells that contain intermediate filaments of Pre-Keratin bound together by desmosomes. It's name which means "spiny layer", refers to what the cells look like once processed for observation.
Located in the S.Basale. Sensory receptors sensitive to touch or compression
(AKA Langerhans Cells) Phagocytic Cells Synthesised in the bone marrow and travel to the S.Spinosum, where they participate in immune response by stimulating a defense against (1) Microorganisms that have penetrated the skin (2) Superficial skin cancers.
("grainy layer") Superficial to the S.Spinosum. Composed of 3-5 layers of Keratinocytes derived from the S.Spinosum. At this point the cells have ceased dividing and have started producing large amounts of Keratin Proteins and keratohyalin. The nuclei and other organelles then disintegrate, and the cells die. This processes creates a tight interlocking layer of cells.
A granular protein structure found in the S.Granulosum that promote dehydration as well as aggregation and cross-linking of the keratin fibers.
("clear layer") found only in the palms and soles.
(horned) The exposed surface of thin and thick skin. Contains 15 to 30 layers of very flat Keratinized cells. Maintianing this layer is done so with a lipid secretion from sebaceous glands. This layer is WATER RESISTANT, but not water proof. Water is lost through insensible perspiration
Formation of a protective superficial layer (S.Corneum) of cells filled with keratin. This process occurs on all exposed skin surfaces as the cells become dryer the corner begin to curl up like cracked dry mud giving it a "horny" appearance
7-10 days to reach the surface of the Stratum Corneum and then an additional 2 weeks until they are shed
interstitial fluid lost by evaporation through the stratum corneum. You are unable to see or feel the fluid loss
Loss of body fluid through secretory activity of sweat glands in quantity sufficient to be observed.
Orange-yellow pigment that accumulated in epidermal cells. Is converted into Vitamin A, which is required for both the normal maintenance of epithelia and the synthesis of photoreceptor pigments in the eyes
Melanin (Manufature & Transport)
Manufactured from the amino acid tyrosine, and packaged in intracellular vesicles called Melanosomes. These vesicels travel with in the processes of the Melanocyte and are transferred intact to the keratinocytes where it forms a protective "umbrella" over the nucleus, shielding the DNA from ultraviolet radiation. They are present only temporarily until the are destroyed by fusion with a Lysosomes
the bluish coloration of the skin due to the presence of deoxygenated hemoglobin in blood vessels near the skin surface
inactive form of vitamin D₃. Converted by the liver to into an intermediary product used by the kidneys to synthesize the hormone Calcitriol
the active form of vitamin D₃ (secreted by the kidneys) that promotes absorption of Ca (and P) from foods in the GI tract into the blood; and inadequate supply leads to impaired bone maintenance and growth.
Usually reserved for essential organic nutrients that must be obtained from the diet because the body either cannot make them or makes them in insufficient amounts.
Epidermal Growth Factor (EGF)
Peptide Growth Factor produced by the salivary glands and glands of the duodenum.
Role of Epidermal Growth Factor
PROMOTING the divisions of basal cells in the S.Basale and S.Spinosum. ACCELERATING the production of keratin in differentiating keratinocytes. STIMULATING epidermal development and epidermal repair after injury. STIMULATING synthetic activity and secretion by epithelial glands
Consists of areolar tissue (L-CT), contains the capillaries, lymphatic, and sensory neurons that supply the surface of the skin. Contain blood vessels and nerve fiber
Deep to the PL, consists of an interwoven meshwork of DI-CT containing both collagen and elastic fibers. Bundles of collagen fibers extend superficially beyond the RL to blend into those of the PL, so the boundary between the two layers is indistinct. contain blood vessels and nerve fiber.
Inflammation of the skin that primarily involves the papillary layer.
Measure of flexibility and resilience, how quickly the skin returns to its normal position after being pinched is a way you can test for loss of skin turgor due to dehydration.
Since collagen and elastic fibers are arranged in parallel bundles oriented to resit the forces applied to the skin during normal movement, invisible tension lines are established. These are clinically significant because a cut parallel to a cleavage line will remian closed and heal with little scarring (A/O) a cut at a right angle that will be pulled open as severed elastic fibers recoil and have great scarring.
a network of arteries formed in the Hypodermis along the boarder of the reticular layer. Supplies the adipose tissue and the subcutaneous layer. Small arteries branch out to supply hair follicles, sweet glands and other dermal structures
Once the cutaneous plexus has reached the papillary layer it branches off into the papillary plexus, which provides arterial blood to capillary loops that follow the contours of the epidermis-dermis boundary.
The papillary plexus empty into a network of small veins that form a venous plexus deep to the papillary plexus
Innervation of the skin
Nerve fibers in the skin control blood flow, adjust gland secretion rates, and monitor sensory receptors in the dermis and the deeper layers of the epidermis. These include Tactile Discs, Tactile Corpuscles, Lamellated Corpuscles
Receptors sensitive to deep pressure and vibration. Found in the reticular layer.
Receptors sensitive to light touch. Found in the dermal papillae.
Not part of the integument, but important in stabilizing the position of the skin in relation to underlying tissue, while permitting independent movement. It is interwoven with the CT fiber so the reticular layer and consists of the LCT Areolar and Adipose.
Compressed, keratinized cells that arise from hair follicles
tubelike organs of the epideris that invaginate into the dermis and secrete hair. Each follicle is wrapped in a DCT sheath and a root hair plexus of sensory nerves surrounds the base of the follicle making it possible for light movements of the hair to be felt; creating an early warning system
a bundle of smooth muscle cells which extends from the papillary layer of the dermis to the connective tissue sheath surrounding the hair follicle. When stimulated the muscle contracts, pulling on the follicle and forcing the hair to stand erect.
The portion that anchors the hair to the skin begins at the hair bulb and extends distally about half way up the saft
is the part which is seen on the surface, extending from the hair root to the tip of the hair
Mass of epithelial Cells that form a cap
a peg of CT containing capillaries and nerves.
The superficial cells of the hair bulb and are responsible for producing the hair. Basal cells near the center of the matric divide and the daughter cells are gradually pushed toward the surface.
Formed by the daughter cells closest to the center of the matrix. (Core of the hair)
An intermediate layer of the hair matrix, lateral the medulla
formed by cells at the edge of the hair matirx (surface of the hair)
Hair/Folicle Structure (inside out)
Medulla, Cortex, Cuticle.
Internal Root Sheath, External Root Sheath, Glassy Membrane, CT Sheath
A follicle that has become inactive at the end of the growth Cycle. The follicle get smaller and the connections between the matrix and the root break down. When a new cycle begins the old hair is pushed out and shed by the new hair.
the fine (and unpigmented) downy hair covering a human fetus.
Fine peach fuzz hairs located over much of the body surface.
Heaven, more deeply pigmented, and sometimes curly. These include, hair on the head, eye brows, eyelashes and pubic hair
reflects differences in structure and variations in the pigment production of melanocytes at the hair papilla
Sebaceous Glands (se-BA-shus)
Oil glands. Holocrine glands that discharge an oily lipid secretion into hair follicles. If it communicates with a single follicle share a duct and thus are classified as simple branched alveolar glands. Gland activity all but stops after birth, but increases again at puberty in response to rising levels of sex hormones.
Oil. Mixture of triglycerides, cholesterol, proteins, and electrolytes. INHIBITS the growth of bacteria, LUBRICATES and PROTECTS the keratin of the hair shaft and CONDITIONS the surrounding skin.
Large sevaceous glands that are not associated with hair follicles; their ducts discharge sebum directly onto the epidermis. Located in the face, back chest, nipples and external genitalia.
a white cheese-like protective material made from shed epidermal cells and sebus that covers the skin of a fetus
(sudor=sweat) Apocrine sweat glands and merocrine sweat glands
Apocrine Sweat Glands
In the armpits, around the nipples and in the pubic region. Secrete their product onto the hair follicles. Produce stick, cloudy and potentially odorous secretion (because it is a nutrient source for bacteria). The cells actually relies on merocrine secretion, but the name has never been changed.
Surround the secretory cells in the Apocrine glands, they contract and squeeze the gland, causing it to discharge. This in controlled by the NS and circulating hormones.
Merocrine Sweat Glands
AKA Eccrine sweat glands, discharge their secretions directly onto the surface of the skin. Far more numerous and widely distributed than ASG. highest numbers are contained in the palms and soles. This is known as sensible perspiration.
Merocrine SG Functions
COOLING the surface of the skin to reduce body temperature. EXCRETING water and electrolytes. PROTECTION from environmental hazards by diluting harmful chemicals in contact with the skin or releasing a powerful antibiotic called dermicidin
Anatomically related to apocrine sweat glands, but go through Holocrine secretion
Modified sweat glands in the external ear canal that work in combination with the nearby sebaceous glands to form cerumen (ear wax) that traps foreign particle
Autonomic Nervous System
Controls the activation and deactivation of sebaceous glands and apocrine sweat glands at the subconscious level. Regional control is not possible; commands issued by the ANS affest all the glands of that type everywhere on the body surface. (AO to merocrine sweat glands which can be much more precisely controlled, amount and location vary independently)
the process of maintaining temperature homeostasis which is a negative feedback reaction.
Protect the exposed dorsal surface of the tips of the fingers and toes. They also help limit distortion of the digits when they are subjected to mechanical stress.
The visible portion of the nail, covers the nail bed. Dead, rightly compressed cells packed with keratin. Changes in the shape, structure or appearance of the nails can provide useful diagnostic info.
Portion of epidermis covered by the nail body
Lateral Nail Grooves
Depressions that the either side of the nail lies in
Lateral Nail Folds
cover the sides of the nail plate. (skin)
The distal portion that continues past the nail bed-extends over the hyponychium
an area of thickened S.cornueum under the free edge of the nail.
An epidermal fold not visible from the surface. The deepest portion of the root lies very close to the bone of the fingertip
Cuticle. A portion of the S.corneum extends over the exposed nail
A pale crescent shaped area at the base of the exposed nail body where the blood vessels under the nail are obscured