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154 terms

Anatomy & Physiology Chapter 7 Skin revised

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Skin
1. body's largest organ, 22 square feet,cutaneous membrane
Integumentary system
describes the skin and its appendages-the hair, nails and skin glands.
2 primary layers of skin
1. epidermis -superfical
2. dermis- true skin joined by dermal-epidermal junction.
Hypodermis
is not part of the skin. AKA subcutaneous layer or superficial fascia.
Structures of the skin- EPIDERMIS
consists of stratified squamous epithelium. There are 4 types present.
Keratinocytes
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.
Melanocytes
produce melanin, a pigement that protects cells from ultraviolet radiation. Melanin from the melanocytes is transferred to the keratinocytes.
Langerhans cells
aka epidermal dendritic cells that interact with WBCs during an immune response
Merkel cells
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
Stratum basale
base layer, single layer of columnar cells; ONLY cells that undergo MITOSIS then migrate through other layers until they are shed.
Stratum spinosum
Spiny layer. cells arranged in 8-10 layers connected by demosomes that pull cells into spiny shapes;rich in RNA.
Stratum germinativum
Fingernail growth is the result of the mitosis of the cells in the stratum __________
Stratum corneum
horny layer. Most superfical layer outer layer of the epidermis
ie dandruff
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.
Calluses
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.
Meissner Corpuscle
capable of detecting light touch-slight pressure.
Lamellar Corpuscle aka Pacinian Corpuscle
detects sensations of deep touch.
DEJ-dermopidermal junction
basement membrane with unique fibrous elements and a polysacchride gel to serve as the "glue" the epidermis and dermis below.
Dermis
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.
Dermis structures
1. Arrector pilli muscles and hair follicles
2. Sensory receptors
3. Sweat and sebaceous glands
4. Blood vessels.
2 layers of dermis
1. papillary layer
2. reticular layer
Papillary layer
Composed of dermal papillae that project into the epidermis; forms a unique that gives individual fingerprints
Reticular layer
contains dense, interlacing white collagenous fibers and elastic fibers to make the skin tough yet stretchable; when processed from animal skin, produces leather
dermis
does not continually shed and regenerate itself as does the epidermis/
fibroblasts
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
______.
Scar.
Melanin
;basic determinant of skin color
2 Types of melanin
1. Eumelanin: group of dark brown almost black melanins
2. Pheomelanin: group of reddish and organge melanins.
Albinism
congenital absence of melanin
hemoglobin
a hemoprotein composed of globin and heme that gives red blood cells their characteristic color, color changes as a result of incresed blood flow.
cyanosis
Bluish color caused by darkening of hemoglobin when it loses oxygen and gains carbon dioxide.
bruising
can cause a rainbow of different colors to appear in the skin
jaundice
yellow discoloration of the skin and other tissues such as the sclera of eyes can be caused by bile pigments.
Surface film
Emulsified protective barrier formed by mixing of residue and secretions of sweat and sebaceous glands with sloughed epithelial cells from skin surface.
Desquamation
shedding of epithelial elements;loss of bits of outer skin by peeling or shedding or coming off in scales
7 Functions of the Skin
1. protection
2. sensation
3. flexability
4. metabolism/endocrine
5. excretion
6. immunity
7. Temperature regulation
Protection/surface film functions
against microorganisms;dehydration;UV light:mechanical trauma
surface film
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
Sensation
skin acts as a sophicated sense organ
Flexability
skin is supple and elactic;permits movement and changes in body contour without injury.
excretion
Water, Urea/ammonia/uric acid
How does skin excrete
sweat glands
a fat-soluble vitamin that prevents rickets
vitamin d
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
Radiation
transfer of heat from one object to another without actual contact; important method of heat loss in cool environmental temperature.
evaporation/insensible loss
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.
appendages
hair, nails, skin glands-sweat and sebaceous and arrector pilli muscle
Lanugo
the fine downy hair covering a human fetus
terminal hair
Course hair on the head and other places after puberty
hair papillae
at bottom of bulb; blood-rich connective tissue, hair growth begins here
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.
growth of hair
5 inches per year
sebaceous glands
attach to and secrete sebum or skin oil into follicle
androgenic alopecia
male baldness pattern, is genetic
nails
epidermal cells converted to hard keratin
nailbody
visible part
lunula
moon shaped white area nearest root
nail bed
layer of epithielum under nail body;contains blood vessels
what are 2 types of sweat glands?
eccrine and apocrine
eccrine glands
most numerous and quite small;distributed throughout body
Function of eccrine glands?
Secrete perspiration or sweat; eliminate wastes and help maintain a constant core temperature
where are apocrine glands located?
deep in sub q layer, limited in axilla, areola, breast and anus.
what is function of apocrine gland?
begins at puberty and secretes cyclic changes such as menstral cycle
Sebaceous glands
secrete sebum keeping hair soft and pliant and prevents water loss
When does sebaceous glands increase production?
puberty
What does the increase of sebaceous glands in teens lead to?
acne
Ceruminous glands
are simple tubular glands, they are apocrine glands.
What does ceruminous glands secrete?
cerumen or wax
What is cerumen made of?
mixed secretions of sebaceous and ceruminous glands
Where is cerumen usually excreted?
ears
How does cerumen protect ears?
protects area from dehydration
What does excess secretion of cerumen cause?
blockage of ear canal and loss of hearing
what are characteristics of skin in children?
smooth, elastic, few sweat glands, rapid healing
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.
What is a major component of skin
it is bodys structural framework
what does skin define?
the internal environment of the body
What are 2 primary functions of skin?
support and protection
Melanin
basic deteminant of color
2 main layers that compose the skin
epidermis and dermis
keratin
tough fibrous protein found in epidermis,made up of keratinocytes
3 microscopic glands of skin are
sweat,eccrine and sebacous glands
hypodermis
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
The epidermis is composed of several types of __________
epithelial cells
Evaporation
is the cause of the conversion of water from a liquid state into a gaseous state due to the bodyheat loss
Contraction
is not a function of the skin
The skin glands include three kinds of microscopic glands. What are they?
. They are the sweat, sebaceous, and ceruminous glands.
cerumen
are mixed secretions of sebaceous and ceruminous glands that form a brown waxy substance
what 3 vitamins are absorbed through the skin?
Vitamin A, vitamin D and Vitamin K
Synthesis of vitamin E
is not a function of the skin
Basal cell carcinoma
is the most common type of skin cancer
Kaposi sarcoma
is the type of cancer associated with immune deficiencies
Prolonged exposure to the sun causes melanocytes which
increases melanin production.
The hair follicle is found?
in the dermis.
Fingernail growth is the result of the mitosis of the cells?
in the stratum germinativum
Apocrine sweat glands
can't be found in the soles of the feet.
Apocrine sweat glands can be found?
in the armpits, the areolae of the breasts and the pigmented skin areas around the anus.
Sebaceous glands are the type of gland associated with_______?
blackheads
Shaft, the root and the medulla are part of ?
hair
Hair facts -
alternates between periods of growth and rest.
-consists of keratinized cells.
-is formed from cells of the germinal matrix.
The hair papilla consists of:
dermal tissue
The most numerous, important, and widespread sweat glands in the body are:
the eccrine glands
what does sebum do?
lubricates hair and skin.
what are the functions of surface film found on the skin?
including:
-lubrication.
- 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.
Evaporation
is the cause of the conversion of water from a liquid state into a gaseous state due to the body heat loss
Radiation
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 ____________
conduction
The body's temperature control center is located in?
the hypothalamus
A second-degree burn is characterized by?
severe pain, generalized swelling, and edema.
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.
the dermis is a
connective tissue
epidermis
is an epithelial tissue
Dendritic cells
Dendritic cells originate in the bone marrow and are important in the immune function
Stratum corneum is the skin layer called
the barrier area.
Stratum lucidum
cell layers are filled with a protein called eleidin
What % of the cells in the stratum basale enter mitosis each day
10%-12%
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.
"Burns" can be caused by:
ultraviolet light.
corrosive chemicals.
electrical current.
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
Stratum spinosum
are cells in which the epidermal layer are rich in RNA to increase the efficiency of protein synthesis
Stratum granulosum
cells layers have a high level of lysosomal enzymes in their cytoplasm
When the skin looks cyanotic, it is because
oxygen-poor blood can be seen through the skin
Fever
increases in body temperature would be caused by pyrogens
Malignant hyperthermia
increase in body temperature can be caused by anesthetics or muscle relaxants
Hair can become brittle and dry due to
the improper function of the sebaceous glands.
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
Onycholysis
is usually caused by trauma to long fingernails.
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
heat stroke
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 fibers in which layer make it possible for skin to stretch and be elastic is the
reticular
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
The following is true of the body's ability to regulate heat loss:
It is part of a negative feedback mechanism.
Sweat glands increase the production of sweat.