Outer most layer of the skin, has no vascular tissue. a stratified squamous of epithelium.
Layer of skin under the epidermis. It contains collagen and elastin fibers. It contains arteries, veins, neurons, sebaceous glands, sweat glands and hair follicles.
-Consists of a papillary layer of areolar tissue and a reticular layer of dense irregular connective tissue.
-(Subcutaneous layer or superficial fascia.) Seperates the integument from the fascia around deeper organs.
-anchors skin to underlying muscle, allows skin to slide over muscle
-acts as a shock absorber & insulator
-NOT APART OF SKIN
A cell in the epidermis that produces keratin.
-The bodys most abundant epithelial cells.
-These cells form several layers, or strata.
-Continuously produced by stem cell divisions in the deepest layers and are shed at the exposed surface.
Extend into the dermis and are adjacent to dermal projections called Dermal Papillae.
-These are what form fingerprints (unique to each individual.)
Why are these ridges (Epidermal ridges and dermal papillae) so important?
They greatly increase the surface area for attachment, firmly binding the epidermis to the dermis.
This type of skin covers most of the body surface, contains four strata, and is about as thick as the wall of a plastic sandwhich bag.
(Strata: Stratum basale, stratum spinosum, stratum granulosum, and stratum corneum.)
This type of skin Occurs on the palms of the hands and the soles of the feet, contains a fifth stratum.
-Includes Stratum Lucidum
-Outermost layer of the skin.
-At the exposed surface of both thick skin and thin skin.
-Normally contains 15-30 layers of keratinized cells.
The dead cells in each layer of the stratum corneum remain tightly interconnected by ____
It takes _ to _ days for a cell to move from the stratum basale to the stratum corneum
7 to 10
-Thick skin of the palms and soles.
-Seperates the stratum corneum from deeper layers.
-flattened, densely packed, filled with the proteins keratin and keratohyalin.
-consists of three to five layers of keratinocytes.
-by the time cells reach this layer, most have stopped dividing and have started making large amounts of keratin and keratohyalin.
-Consists of 8-10 layers of keratinocytes bound together by desmosomes.
-Contains dendritic cells. (participate in the immune response)
-Participate in the immune response by stimulating a defense against 1)microorganisms that manage to penetrate the superficial layers of the epidermis and 2)superficial skin cancers.
-A part of the Stratum Spinosum.
-Basal layer of the epidermis.
-Basal cells dominate this layer.
-dominate the stratum basale
-stem cells whose divisions replace the more superficial keratinocytes that are lost or shed at the epithelial surface.
-Cells that are sensitive to touch.
-When compressed, they release chemicals that stimulate sensory nerve endings.
What determines skin color?
-Presence of pigments in the skin
-The degree of dermal circulation
-thickness and degree of keratinization in the epidermis.
The primary pigments involved in skin coloration are:
Brown, yellow-brown, or black pigment produced by melanocytes.
-Determines skin color.
An orange yellow pigment that normally accumulates in epidermal cells.
-Most apparent in cells of the stratum corneum of light skinned individuals.
-it also accumulates in fatty tissues in the deep dermis and hypodermis.
Your skin becomes flushed and red when your body temperature rises because the superficial blood vessels dilate so that the skin can act as a radiator and lose heat.
The blood supply affects skin color.
Red pigmentation found in red blood cells
When blood flow ___, oxygen levels in the tissues decline, and under these conditions hemoglobin releases oxygen and turns a much darker red.
A network of Capillaries that provides oxygen and nutrients to the dermis and epidermis
-contained in the papillary layer of the skin
___ cancers are the most common type of cancers
The most common form of skin cancer
Basal cell carcinoma
Cancer that originates in the stratum basale, due to the mutations caused by overexposure to the UV radiation in sunlight
Basal cell carcinoma
Two types of fibers in the dermis enables the dermis to tolerate limited stretching
Are very strong and resist stretching but are easily bent or twisted.
permit stretching and then recoil to their original length.
Aging, horomonal changes, and the destructive effects of ultraviolet radiation permanently reduce the amount of elastin in the dermis. This causes ____
Wrinkles and sagging skin
Consists of a highly vascularized areolar tissue with all of the typical cell types within it.
-Contains capillaries, lymphatic vessicles, and sensory neurons that supply the surface of the skin.
Layer of skin that consists of an interwoven meshwork of dense irregular connective tissue containing both collagen and elastic fibers.
The boundaries between the reticular layer and papillary layer is distinct.
False. it is indistinct.
Does the papillary and reticular layer contain hair follicles and sweat glands?
This layer of the skin seperates the skin from deeper structures. It stabilizes the position of the skin in relation to underlying tissues while also permitting independent movement.
Sensory terminals known as ___ monitor merkel cells
The portion that anchors the hair into the skin- extends from the base of the hair follicle, where hair production begins, to the point where the hair shaft loses its connection with the walls of the follicle.
produces secretions that coat the hair and the adjacent surface of the skin
A complex structure composed of epithelial and connective tissues that is responsible for the formation of a single hair.
Large, Coarse, often darkly pigmented hairs such as those found on the scalp or the armpits
smaller, shorter, and more delicate hairs found on the general body surface.
This forms the surface of the hair.
-consists of daughter cells produced at the edges of the hair matrix
the intermediate layer of cells deep to the cuticle.
cells at the center of the hair matrix
The superficial cells of the hair bulb. germative cells in this produce the hair.
small connective tissue peg filled with blood vessels and nerves
the smooth muscle that forces the hair to stand erect. (upright).
Surrounds the hair root and the deeper portion of the shaft. the cells of this sheath disintegrate quickly, and this layer does not extend the entire length of the hair follicle
Internal Root Sheath
consists of epithelial cells and extends from the skin surface to the hair matrix.
External root sheath
Thickened, clear basal lamina
A hair in the scalp grows for _ to _ years
2 to 5
Variations in hair color reflect differences in structure and variations in the pigment produced by melanocytes at the ____
Holocrine glands that discharge an oily lipid secretion.
sebaceous glands secrete ___ which coats the hair shaft and surrounding epidermal surfaces.
-provides lubrication and keeps the hair shaft from becoming dry and brittle.
contractile cells that squeeze the gland and discharge the accumulated secretion.
found in the armpits, around the nipples, and in the pubic regions where they secrete into hair follicles.
-strongly influenced by horomones.
Apocrine sweat glands.
sweat glands that discharge their secretions directly onto the surface of the skin. the palms and soles have the highest numbers.
Merocrine sweat glands.
The part of the nail that consists of dead, tightly compressed cells packed with keratin.
The nail body is recessed deep to the level of the surrounding epithelium and is bounded on either side by ___ (depressions) and ___ (ridges)
Lateral nail grooves
Lateral nail folds.
The nail body covers an area of epidermis called the ____
The formal name for the cuticle of the nail :
Nail production occurs at the ___, an epidermal fold not visible from the surface.
___ activity declines, and in light-skinned individuals the skin becomes very pale.
-With less of this in the skin, people become more sensitive to sun exposure and more likely to experience sunburn
Over time, The connections between the epidermis and ___ weaken, making older people more prone to injury, skin tears, and skin infections.
The Dermis becomes thinner and has fewer ___ fibers, making the integuement weaker and less resilient. What are the results?
-Wrinkling and sagging
___ sweat glands become less active, and with impaired perspiration, older people cannot lose heat as fast as younger people. What are the results?
-The elderly are at greater risk of overheating in warm environments.
Reduced circulation and sweat gland function in the elderly lessens their ability to loose body heat.
hair follicles stop functioning or produce thinner, finer hairs. With decreased ___ activity, these hairs...?
-turn grey or white
Steroid hormones called ___ are released during times of stress. These hormones loosen the connection between keratinocytes and reduce the effectiveness of the epidermis as a barrier to infection
Thyroid gland hormones maintain normal blood flow to the ___
Sex hormones stimulate epidermal cell divisions, increasing epidermal thickness and accelerating ___ ____
___ ____ are compounds produced in the body that stimulate cell growth and cell divisions.
This peptide is produced by the salivary glands and glands of the duodenum, the initial segment of the small intestine.
Epidermal growth factor. (EGF)
-Promoting the divisions of germinative cells in the stratum basale and stratum 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.
These are all roles of the _________
epidermal growth factor
Limited exposure to sunlight is beneficial because UV radiation plays a vital role in the synthesis of an important vitamin: ____
A condition that results in flexible, poorly mineralized bones.
-Develops in a growing child whose skin is not exposed to sunlight, and whose diet does not include a source of Cholecalciferol (vitamin D3)
A raised, thickened mass of scar tissue that begins at the site of injury and grows into the surrounding dermis
Melanin is produced by melanocytes within the stratum ___
Which layer of the DERMIS (papillary, reticuluar) has loose aerolar connective tissue?
The layer of skin that contains the blood vessels and nerves that are closest to the surface of the skin is the ___ layer:
variations in hair color reflect differences in structure and variations in the pigment produced by melanocytes at the ____
Myoepithelial cells are found in what structures?
Apocrine and merocrine sweat glands
The nail body covers the ___
The repair of the epidermis after a wound begins as basal cells produce new:
Which structural feature of the hair consists of germanative cells that produce the hair?
Which hormone, synthesized by the kidneys, is required for normal bone growth and maintenance?
During the ___ phase, the hair looses its attachment to the follicle and becomes a club hair
Growth hormone stimulates ___ activity and collagen synthesis
The integumentary layer consisting of 8-10 layers of keratinocytes that are bound together by desmosomes is the :
What layer of the cutaneous membrane contains blood vessels that assist in thermoregulation?
Reticular layer of the dermis
Contractile cells that squeeze exocrine glands of the skin and discharge the accumulated secretion
What substance is produced by the salivary glands and glands of the duodenum?
Epidermal growth factor
after ___ of a skin injury, the phagocytic activity around the site has almost ended, and the blood clot disenigrates
Cells have stopped dividing and have started making large amounts of keratin and keratohyalin by the time they reach which layer?
Near the nail root, the dermal blood vessels may be obscured, leaving a pale crescent area known as the __________.
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