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The color of the skin comes form three classes of (skin) pigments:
- 1. Melanin
- -Pheomelanin (yellow to red)
- -Eumelanin (brown to black)
- 2. Hemoglobin
- 3. Carotene
What are the two kinds of melanin?
- pheomelanin, which is yellow to red
- euelanin, which is brown to black
- in hair these (granules) are scattered among the keratin fibers
- in skin, these pigments are found in cells called melanocytes
- Almost everyone has roughly the same number of melanocytes
- difference in skin color is deturmined by the amount of pigment in each melanocyte.
_________ is made from the amino acid tyrosine in an organelle called ___________. The pigment is _______ to keratinocytes, giving ______ and _____ there color
melanin, melanosome, transferred, hair, epidermis
A mole (or nevus) is formed when:
melanocytes accumulate in ine region
True ore false: Melanocytes are normally scattered more-or-less throughout the epidermis
- mostly in deeper areas (spinosum and basale)
In light-skinned persons...
- little melanin is made and stored in melanocytes
- in theses people the color of the skin is predominantly due to hemaoglogin
a red pigment in blood that gives the skin a pinkish cast.
- a precursor to vitamin A
- found in intensely colored fruits and vegetables.
- there was a plummer who ate so many carrots and tomatoes this his skin turned orange
In some diseases, such as _______ ______, the pigment ________ accumulates in the _____, giving it a yellow color.
liver failure, bilirubin, skin
- A symptom of liver disease
- symptom of turning yellow (particular easy to see in the "whites" of the eyes)
- A dense connective tissue layer beneath the epidermis
- There are few cells
- it is mosly collagen and elastic fibers
- There are two regions of the dermis
- -papillary region
- reticular region
When the ______ of farm animals is chemically treated it is called ______.
- superficial portion of the dermis (about 1/5 its thickness)consists of areolar connetive tissue with thin collagen and fine elastic fibers
- contains dermal ridges that penetrate up into the epidermis
- each of these tend to contain capillaries, blood vessels and sensory structures known as Meissner corpuscles and free nerve endings
What are the functions of Meissner corpuscles?
Sensing light and touch
What are the functions of free nerve endings?
sensings pain, temperature, and itch
The _________ region is important for its _____ attachment to the epidermis. Also on the ______, ______, and soles of the feet, the underlying structure of the dermis causes the skin to have ____________.
papillary, tight, palms, fingertips, fingerprints
- The deeper portion of the dermis (about 4/5 of its thickness)
- Consists of dense irregular connective tissue with bundles of thick collagen and some coarse elastic fibers.
- Spaces between fibers contain some adipose cells, hair folicles, nerves, sebaceous glands, and sudoriferous glands
True or false: The dense connective tissue of the drmis is strong and resilient; it can be sretched, and it snaps back to its original form.
What are striae ?
- More commonly known as "stretch marks"
- Tears in the dermis caused by stretching, i,e: obesity or pregnancy
- these are seen on the skins surface.
- (not tipically included in the skin proper)
- A loose connective tissue made up of areolar and adipose tissues
- Blood vessels pass through this layer on their way to the dermis.
- Lamellated (Pacinian) corpuscles, a kind of nerve ending mediating the felling of vibration, are found in the lower dermis and upper part of the this layercommon place to give injecitons
- abbreviated - subQ
- An example of an areolar connective tissue
Where is adipose tissue (fat) located?
the subcutaneous layer of the skin
What are the Sensory Receptors/Sensory Nerve Endings?
- 1. Meeisner (touch) corpuscles: light touch
- 2. Merkel (tactile) disks: light touch
- 3. Free nerve endings: pain & temp, itch, hair movement
- 4. Pacinian (lamellated) corpuscle: deep pressure, vibration
- Also sensation from nerve nerworks around hair roots in thin skin
At the interface between epidermis and dermis, in the papillary region, are the ...
...Meissner corpuscles, Merkel discs, and free nerve endings.
Deep in the skin, at the border of the dermis and the subcutaneous layer, is the _______ ________ _______.
Pacinian (lamellated) corpuscle.
- these are layered like and onion
- this special shape means that the nerce ending inside the responds preferentially to vibration.
Scientist believe that the actual finciotn of ________ ______ is to detect the slippage of thick skin (_____ and _____)against a surface, as when you lose your grip on a branch. As the hand slips, its alternate grabbing and _______ causes a _______ against the branch, signalling an importantg message: "Your going to fall, dude"
"vibration" receptors, fingers, palm, slipping
Graphic objective 12. Give the location of nails, describe their anatomy, and demonstrate knowledge of their function.
- Hair shaft has three layers
- - this is what we see externally
- - cuticle (purple layer) is outermost for external hairs
Pigment cells (melanocytes) and blood vessels at base
The external portion of hair is made up of three concentric layers:
The medulla in the center, a cortex further out, and finally a covering, or cuticle, on the outside.
Beneath the surface of the skin, the ____ _______ and ______ ____ ______ surround the medulla, cortex and cuticle. At the base, ther are _____ ______ and melanocytes.
hair follicle; dermal root sheath; blood vessels
Color comes from pigment _______ trapped along with the ______ ______ in the hair shafts.
granules (brown or black eumelanin; blonde or red pheomelanin); keratin protein
White or gray hair occurs when pigment production is _______ or halted and ___ ______ replace pigment.
reduced; air bubbles
Hair follicle includes:
Internal root sheath; External root sheath; Dermal root sheath
In the hair root, additional layers of epidermis form a root sheath. The ______ ____ ______ surrounds the whole root of the hair. At the base, a small plexus of _____ _______ supplies _______ to the growing hair and the melanocytes.
dermal root sheath; blood vessels; nutrition
A single bundle of ______ muscle cells, the _______ ____ muscle, can contract to make the hair stand on end, or relax to let it lay flat. A ________ gland is associated with the hair root.
smooth; arrector pili; sebaceous