Chapter 6 Flashcards
Integumentary System
The integument (skin) is the
largest organ of the body composed of all the tissue types that function to protect the internal structures of the body.
The skin accounts for ____ of the total body weight.
7-8%
The skin consists of two distinct layers:
Epidermis
Dermis
epidermis is made of
keratinized stratified squamous epithelium
dermis is made of
both areolar and dense irregular connective tissue
under the dermis lies the
hypodermis (subcutaneous layer)
hypodermis is made of
both areolar and adipose connective tissue.
five layers of the epidermis
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale
which layers of the epidermis are made of living cells?
Stratum granulosum
Stratum spinosum
Stratum basale
which layer of the epidermis is only found in thick skin?
stratum lucidum
where is thick skin found?
palms of hands
soles of feet
three cell types that reside in the stratum basale?
keratinocytes
melanocytes
merkel cells
keratinocyte stem cell function
divide to replace dead keratinocytes that are shed from the surface.
what does keratin do for the skin?
provides water resistance
melanocyte function
store and produce melanin in response to UV light to protect DNA from damage.
merkel cell function
tactile cells that are sensitive to touch and release chemicals that act on nerves to send touch impulses to the brain.
The keratinocytes in the stratum spinosum layer are
highly specialized and do not continue cell division.
specialty cell that resides in the stratum spinosum
epidermal dendritic cells (Langerhans)
langerhans cell function
help to provide immune protection for the epidermis.
Cells are not fully keratinized until
they reach the superficial most layer
fully keratinized cells have
no nucleus or organelles
what is keratinization?
where the cells begin synthesis of large amounts of keratin
what does keratinization lead to?
disintegration of the nucleus and organelles, leading to cell death.
where does keratinization occur in the epidermis?
stratum granulosum
The stratum lucidum is a (color)
clear, thin layer roughly 2-3 keratinocytes thick
where does the translucency of the stratum lucidum come from?
protein eledin
the stratum corneum is the
most superficial layer of the epidermis
the stratum corneum consists of
20 to 30 layers of dead, interlocking, keratinized cells
keratinized cells of the stratum corneum are also considered
cornified
thick skin contains
all five layers of epidermal tissue and has sweat glands (no hair follicles or oil glands)
thin skin contains
4 epidermal layers sweat glands, hair follicles, and oil (sebaceous) glands.
three molecules that contribute to skin color
hemoglobin, melanin, and carotene.
hemoglobin is ____ and does what?
a protein in red blood cells that binds to oxygen, and upon binding, it exhibits a bright red color, giving blood vessels in the dermis a reddish tint.
two forms of melanin
eumelanin
pheomelanin
eumelanin produces
shades of brown and black
pheomelanin produces
lighter shades of tan, yellow, and red.
carotene is ____ and comes from where?
yellow-orange pigment that is acquired from similar colored vegetables like carrots, corn, and squashes
one example of the many forms of carotene
beta-carotene
how is skin color influenced?
genetics and UV exposure of the skin. These affect the color of melanin and melanocyte activity, affecting skin color.
everyone has roughly the same number of melanocytes
Albinism is
an inherited condition where the enzyme tyrosinase (to produce melanin) is nonfunctional, therefore no melanin is produced from melanocytes.
Nevus/nevi are
harmless, localized overgrowth of melanocytes. Rarely, moles can become cancerous resulting from excessive UV exposure.
Freckles are
spots that represent localized areas of increased melanocyte activity, not an increase in melanocyte quantity.
Hemangiomas are
anomalies that result in skin discoloration from blood vessels that proliferate and form a benign tumor
Individuals with albinism have
white hair, pale skin, and pink irises of the eyes.
Capillary hemangiomas are
present at birth and disappear into childhood
cavernous hemangiomas may
last a lifetime
Since no melanin is produced in albinism, what risks are there for affected individuals?
skin cancer
photophobia
the dermis contains mainly which protein fiber?
collagen
Dendritic cells are
cells found in the dermis and serve the same immune protection as epidermal dendritic cells
The dermis is divided into two layer
papillary and reticular
The papillary layer of the dermis sits
directly under the epidermis and on top of the reticular layer
The papillary layer of the dermis is composed of
areolar connective tissue.
what is the papillary layer named atfer?
dermal papillae projections that interconnect with the epidermal ridges of the epidermis.
where does the epidermis receive blood supply and nutrients?
dermal papilla blood vessels
The reticular layer consists of
dense irregular connective tissue with large collagen fibers that extend in all directions.
reticular layer fibers are interwoven into
a meshwork that surrounds hair follicles, sweat and oil glands, nerves, and blood vessels.
in areas of the hypodermis where adipose connective tissue is dominant, it is called
subcutaneous fat.
The hypodermis acts as
cushion and protection to structures underneath, energy storage, and thermal insulation.
Subcutaneous drug injection is often used due
to the vascularity of the hypodermis, allowing for rapid uptake of drugs
what will influence thickness and distribution of subcutaneous fat?
Sex hormones
Testosterone - neck, upper arms, abdomen, lower back, and butt.
Estrogen/progesterone - thicker overall and accumulates in mammary regions, butt, hips, and thighs.
eight main functions of the integument
protection from environment
water control
vitamin D synthesis
secretion
absorption
temperature regulation
immune function
sensory function
Dehydration is a huge risk in extreme burn victims because?
Large amounts of water is lost when there is no skin barrier to help seal it in.
transdermal administration occurs because?
the skin is selectively permeable and some substances can pass through
transdermal drug administration allows for?
continuous, slow release of the drug.
two main epidermal derived structures
nails and hair
nails are
modifications of the stratum corneum layer of the epidermis
nails provide
protection of the distal tips of the fingers and toes, along with assistance in grasping objects.
hair functions
protection, heat retention, sensory reception, and visual identification (age)
The nail bed contains
living epidermal cells.
The nail body is darker and pinker from ______, while the lunula is whiter from
underlying blood vessels
the stratum basale layer obscuring the vessels.
A single hair is called
pilus, composed of keratinized cells (dead)
Three forms of hair
lanugo
vellus
terminal hair
lanugo is
fine, unpigmented hair that grows during the third trimester of fetal development
Terminal hair comes in on
scalp, eyebrows, and eyelashes
vellus is
lightly pigmented and also remains on the upper and lower limbs
also replaces lanugo
Terminal hair replaces
vellus hair of the axillary and pubic regions
Arrector pili is the
smooth muscle associated with the hair shaft and contracts under states of emotion (fear/rage) or cold temperatures (goosebumps)
Hair color is determined by
melanin synthesized in the matrix adjacent to the hair papilla.
Hair growth stages
Anagen phase is the active growth phase of hair where living cells in the bulb are growing and dividing
Catagen phase is a regression period where cell division stops and the follicle shrinks
Telogen phase is the resting phase and when hair is shed
when is hair loss abnormal?
more than 100 hairs lost per day
Alopecia
autoimmune disease where the immune system attacks the hair follicles, causing baldness
Male pattern baldness
genetic/hormonal, hair is lost from the crown of the head
Hirsutism
excessive terminal hair growth in areas without terminal hair (usually from testosterone levels being high from PCOS)
The two most common exocrine glands of the skin are
sweat and sebaceous glands.
There are two forms of sweat glands
merocrine (eccrine) and apocrine
myoepithelial cells of sweat glands contract in
response to nervous system signals and discharge their contents.
Myoepithelial cells are
specialized epithelial cells that have contractile proteins found in muscle.
a sweat pore is
The opening on the epidermal surface
Merocrine sweat glands are the most
numerous and widely distributed sweat glands in the body, with the primary function of thermoregulation.
Apocrine sweat glands are found in the
axillary region, mammary region around the nipples, pubic region, and anal region
Apocrine sweat glands become active
around puberty.
These glands are associated with body odor as the secretions produced contain proteins and lipids that are acted on by bacteria which create this odor.
Sebaceous glands are
holocrine glands that produce sebum
Sebum acts as a
lubricant to protect the hair and skin from becoming dry, brittle, and cracked. Sebum also has antibacterial properties.
Sebum is a
waxy, oily secretion that is discharged into a hair follicle and onto the hair shaft.
Sebum secretion is stimulated and influenced by
sex hormones and production is low in childhood, but always activated in puberty.
other glands of the integument that are specialized and localized to one area
ceruminous glands and mammary glands.
Ceruminous glands are
modified apocrine sweat glands located in the external ear canal and produce a waterproof secretion called cerumen.
Cerumen acts as a
lubricant for the external ear and sticky trap against foreign particles and small insects.
Mammary glands are
modified apocrine sweat glands found in both males and females.
Mammary glands become active and functional in
pregnant and lactating females
mammary glands produce
breast milk
Damaged tissues repair either through
regeneration or fibrosis.
Regeneration is
the replacement of damaged or dead cells with the same cell type by cell division. Regeneration will restore tissue function.
When the tissue is too damaged or the cells cannot divide
fibrosis occurs, a process of scar tissue deposition, which binds the damaged parts together. Scar tissue is a fibrous form of connective tissue. While the structural aspect of the area can be restored, the function is not.
Regeneration process:
Cut blood vessels result in blood release into the wound, bringing clotting proteins, white blood cells, and antibodies.
A blood clot forms and temporarily patches the edges of the wound together and acts as a barrier to keep pathogens out
The cut blood vessels regenerate and grow in the wound, creating granulation tissue. Macrophages begin removing the clotted blood and fibroblasts in the dermis produce new collagen fibers.
Epithelial regeneration occurs at the skin surface and these cells migrate over the wound, moving internally to the scab (superficial remains of the clot), and connective tissue is replaced by fibrosis.
some skin changes in middle age and their physiological cause
wrinkles, crease lines, thinner hair/baldness, thinner skin (from decreased epidermal activity)
Skin repair begins to take longer as cell activity has decreased, collagen fibers decrease, and elastic fibers lose their elasticity.
Overexposure to UV rays can cause
DNA damage and accelerate aging, along with increasing DNA mutations, leading to skin cancer
Basal cell carcinoma is
the most common skin cancer but least dangerous as it rarely spreads in the body
Basal cell carcinoma usually occurs on
the face
basal cell carcinoma starts in the
stratum basale
Squamous cell carcinoma forms from
keratinocytes of the stratum spinosum
Malignant melanoma is
the most dangerous form of skin cancer due to its rapid spread and metastasis to other areas in the body
Malignant melanoma arises from
melanocytes in a pre-existing mole
