2 primary layers of skin
1. epidermis -superfical
2. dermis- true skin joined by dermal-epidermal junction.
Structures of the skin- EPIDERMIS
consists of stratified squamous epithelium. There are 4 types present.
produces keratin, a protein that hardens and waterproofs the skin. Mature keratinocytes at the skins surface are dead and filled almost entirely with keratin. It protects body from microbes, abrasions, chemicals. Most superficial and constitutes 90% of cells present.
produce melanin, a pigement that protects cells from ultraviolet radiation. Melanin from the melanocytes is transferred to the keratinocytes.
Tactile epithelial cells that attach to sensory nerve endings to form "light touch" receptors. Serves as a sensory function.
5 layers of EPIDERMIS
1. Stratum granuloseum
2. Stratum lucidum
3. Stratum corneum
4. Stratum basale
5. Stratum spinosum
base layer, single layer of columnar cells; ONLY cells that undergo MITOSIS then migrate through other layers until they are shed.
Spiny layer. cells arranged in 8-10 layers connected by demosomes that pull cells into spiny shapes;rich in RNA.
Fingernail growth is the result of the mitosis of the cells in the stratum __________
Epidermal growth and repair/Turnover or regeneration
most important function of skin is protection. Largely depends on epidermis and its ability to create and repair itself after injury or disease. turnover or regeneration time in the stratum basale and migrate to skin surface. TIME: 35 days.
shortened turnover time will increase the thickness of the stratum corneum and results in callus formation; a thickened stratum corneum
Epidermal Proliferating Unit- EPU
each group of 8-10 basal cells in mitosis with their vertical columns of migrating keratinocytes is called an EPU.
basement membrane with unique fibrous elements and a polysacchride gel to serve as the "glue" the epidermis and dermis below.
True skin. Much thicker than the epidermis and lies beneath it.
-gives strenght to skin
-serves as a reservior area for storage of water and electrolytes.
-rich vascular supply plays critical role in TEMPERATURE REGULATION.
1. Arrector pilli muscles and hair follicles
2. Sensory receptors
3. Sweat and sebaceous glands
4. Blood vessels.
Composed of dermal papillae that project into the epidermis; forms a unique that gives individual fingerprints
contains dense, interlacing white collagenous fibers and elastic fibers to make the skin tough yet stretchable; when processed from animal skin, produces leather
During wound healing, _______ begin forming an unusually dense mass of new connective fibers; if not replaced by normal tissue, this mass remains a scar
During wound healing, fibroblasts begin forming an unusually dense mass of new connective fibers; if not replaced by normal tissue, this mass remains a
2 Types of melanin
1. Eumelanin: group of dark brown almost black melanins
2. Pheomelanin: group of reddish and organge melanins.
a hemoprotein composed of globin and heme that gives red blood cells their characteristic color, color changes as a result of incresed blood flow.
Bluish color caused by darkening of hemoglobin when it loses oxygen and gains carbon dioxide.
yellow discoloration of the skin and other tissues such as the sclera of eyes can be caused by bile pigments.
Emulsified protective barrier formed by mixing of residue and secretions of sweat and sebaceous glands with sloughed epithelial cells from skin surface.
shedding of epithelial elements;loss of bits of outer skin by peeling or shedding or coming off in scales
7 Functions of the Skin
7. Temperature regulation
mechanical barrier of skin;Emulsified protective barrier formed by mixing of residue and secretions of sweat and sebaceous glands with sloughed epithelial cells from skin surface
The skin keeps the body immune by
having epidermal dendritic cells trigger helpful immune reaction working with helper T cells
Heat production/homeostasis of body temperature
by metabolism of foods in skeletal muscles and liver
Chief determinant of heat production is?
the amount of muscular work being performed. Example exercise.
homeostasis of body temperatures
to maintain homeostasis of body temperature heat production must be equal to heat loss;skin plays a crtical role in the process.
homeostatic of regulation of heat loss
the heat loss by the skin is controlled by a negative feedback loop;receptors in the hypothalmus monitor the bodys internal temperature. If the bodys temp is increased, the hypothalmus continues to act until the bodys temperature returns to normal
transfer of heat from one object to another without actual contact; important method of heat loss in cool environmental temperature.
to evaporate any fluid, heat energy must be expended;this method of heat loss is especially important at high environmental temps when the only method by which heat can be lost from the skin.
arrector pili muscle
Each hair follicle has a small bundle of involuntary muscles attached to it called the arrector pili muscles.Part of the sebaceous gland, follicle and hair to a standing position, goose bumps.
Function of eccrine glands?
Secrete perspiration or sweat; eliminate wastes and help maintain a constant core temperature
what is function of apocrine gland?
begins at puberty and secretes cyclic changes such as menstral cycle
What occurs in skin cycle in adults?
development and activation of sebaceous and sweat glands, increase sweat production, can cause body odor and acne.
What happens to skin in old age?
decrease in secaeous and sweat gland activity, wrinkles, decrease in ability of body to cool itself.
Forms a connection between skin and underlying body structure; deep to dermis, mostly fat.hypodermis connects the dermis to the underlying tissues.
An area of the body you would expect to find an especially thick stratum corneum is in the
sole of the foot
is the cause of the conversion of water from a liquid state into a gaseous state due to the bodyheat loss
The skin glands include three kinds of microscopic glands. What are they?
. They are the sweat, sebaceous, and ceruminous glands.
Apocrine sweat glands can be found?
in the armpits, the areolae of the breasts and the pigmented skin areas around the anus.
Hair facts -
alternates between periods of growth and rest.
-consists of keratinized cells.
-is formed from cells of the germinal matrix.
what are the functions of surface film found on the skin?
- buffering of caustic irritants.
- antibacterial and antifungal activity
Although body temperature normally changes very little during the course of a day, it is generally the lowest during_______?
the early morning.
is the cause of the conversion of water from a liquid state into a gaseous state due to the body heat loss
is the type of body heat loss that characterized by heat transfer from the surface of one object to the surface of another object without actual contact
How does the body compensates for the increase in the core body temperature caused by exercise ?
by increasing the blood flow to the skin.
The same degree of environmental temperature seems hotter in humid climates than it does in dry ones, why?
because evaporation is retarded in humid climates
A person leaning against a cold cement block wall would lose heat by the process of ____________
A major distinction between second- and third-degree burns is that ?
third-degree burns are characterized by insensitivity to pain immediately after injury.
First degree burn
s damage the outer layer of skin (epidermis) and cause pain, redness and swelling (erythema)
Second degree burns
damage the epidermis and the inner layer, the dermis, causing erythema and blistering
third degree burns
extend into the hypodermis, causing destruction of the full thickness of skin with its nerve supply (numbness). Third degree burns leave scars and may cause loss of function and/or sensation.
Dendritic cells originate in the bone marrow and are important in the immune function
The following is true of the dermal-epidermal junction:
It is composed chiefly of basement membrane.
Its function is to "glue" the two layers of skin together.
The following is true of the dermis:
It contains a papillary layer.
It contains a reticular layer.
It plays an important role in body temperature regulation.
The cell layers of skin from the most superficial to the deepest appear in this order
The cell layers of skin from the most superficial to the deepest appear in this order: Stratum corneum, lucidum, granulosum, spinosum, and basale CLGSB
The time required for the completion of mitosis, differentiation, and the movement of new cells from the stratum basale to the surface of the skin is
about 35 days
are cells in which the epidermal layer are rich in RNA to increase the efficiency of protein synthesis
increase in body temperature can be caused by anesthetics or muscle relaxants
Many liquid medicines, such as insulin, are administered using a subcutaneous injection
The subcutaneous layer has a rich blood supply and loose spongy texture which makes it an ideal site for the administration of such medication
After several hours of landscaping the yard, Jennifer experienced a body temperature of 105° F; a rapid heart rate; headache; and hot, dry skin. She is taken to a medical facility and treated for
Matt is admitted to the hospital with burns to the deep epidermal layers and injury to the upper layers of the dermis. The physician tre ats Matt's condition as
a second-degree burn.
After several months of extensive weight training, Nick has noticed pinkish, depressed furrows with jagged edges in his axillary region. These markings are a result of
healing due to tiny tears in the dermis.
Somatic sensory receptors
are a special network of nerves deep in the dermis that is capable of detecting pressure on the skin surface
This is a true statement that best explains the importance of the dendritic cells:
They find markers on bacteria and other invaders and present them to other immune system cells for recognition and destruction
The regeneration time required for completion of mitosis, differentiation, and movement of new keratinocytes from the stratum basale to the surface of the epidermis be accelerated by
the epidermal proliferating unit
The skin of an infant is more easily damaged by penetration or abrasion than that of an adult. WHY?
Stratum corneum layer is probably thinner in an infant than in an adult
The following is true about thick or thin skin:
Thin skin is hairless.
Most of the body is covered in thin skin.
Epidermal ridges are found in thick skin.
The following is true of dermal growth and repair
In the healing of an injury, fibroblasts reproduce and begin to form new connective tissue
Surgical incisions made parallel to cleavage lines are less likely to leave a scar
The excretory function of the skin includes all of the following:
influencing the fluid volume of the body.
removing uric acid and urea from the body