A/P Ch 5
Flash cards
What are the major regions of the
skin?
What are the major regions of the
skin?
1. Epidermis – outermost superficial region
2. Dermis – middle region
3. Hypodermis (superficial fascia) – deepest
region
)
Figure 5.1
Hair shaft
Pore
Dermal papillae
(papillary layer
of dermis)
Epidermis
Meissner's corpuscle
Free nerve ending
Reticular layer of dermis
Sebaceous (oil) gland
Arrector pili muscle
Dermis
Sensory nerve fiber
Eccrine sweat gland
Pacinian corpuscle
Artery
Hypodermis
(superficial
fascia)
Hair root
Hair follicle
Eccrine sweat
gland
Vein
Adipose tissue
Hair follicle receptor
(root hair plexus)
Figure 5.1
Describe the Epidermis
•
•
•
•
Composed:
Cell Types:
Cell Layers:
Main Function:
Describe the Epidermis
• Composed: keratinized stratified squamous
epithelium
• Cell Layers: Stratum Corneum, Stratum
Lucidum, Stratum Granulosum, Stratum
Spinosum, Stratum Basale
• Cell Types:keratinocytes, melanocytes, Merkel
cells, and Langerhans’ cells
• Main Function: protection
Layers of epidermis
What is Keratinocytes?
What is Keratinocytes?
produce the fibrous protein keratin
What is Melanocytes?
What is Melanocytes?
produce the brown pigment melanin
What is Langerhans’ cells?
What is Langerhans’ cells?
epidermal macrophages that help activate
the immune system
What are Merkel cells?
What are Merkel cells?
function as touch receptors in association
with sensory nerve endings
Describe the Stratum Basale
Describe the Stratum Basale
• Deepest epidermal layer firmly attached
to the dermis
• Consists of a single row of the youngest
keratinocytes
• Cells undergo rapid division
Describe Stratum Spinosum
Describe Stratum Spinosum
• Cells contain a weblike system of
intermediate filaments attached to
desmosomes
• Melanin granules and Langerhans’ cells
are abundant
• “Prickly Layer”
Describe Stratum Granulosum
Describe Stratum Granulosum
• Thin; three to five cell layers in which
drastic changes in keratinocyte
appearance occurs
• Keratohyaline and lamellated granules
accumulate in the cells of this layer
Describe the Stratum Lucidum
Describe the Stratum Lucidum
• Thin, transparent band superficial to the stratum
granulosum
• Consists of a few rows of flat, dead
keratinocytes
• Present only in thick skin
• “Clear Layer”
Describe the Stratum Corneum
Describe the Stratum Corneum
• Horny Layer
• Outermost layer of keratinized cells
• Accounts for three quarters of the epidermal thickness
• Functions include:
– Waterproofing
– Protection from abrasion and penetration
– Rendering the body relatively insensitive to biological,
chemical, and physical assaults
Describe the Dermis
Describe the Dermis
•
Second major skin region containing
strong, flexible connective tissue
•
Cell types include: fibroblasts,
macrophages, and occasionally mast cells
and white blood cells
•
Composed of two layers
1. Papillary
2. reticular
Describe the Papillary Layer
Describe the Papillary Layer
– Areolar connective tissue with collagen and
elastic fibers
– Its superior surface contains peglike
projections called dermal papillae
– Dermal papillae contain capillary loops,
Meissner’s corpuscles, and free nerve
endings
Describe the Reticular Layer
Describe the Reticular Layer
– 80% of the thickness of the skin
– Collagen fibers in this layer add strength and
resiliency to the skin
– Elastin fibers provide stretch-recoil properties
What is the Hypodermis?
What is the Hypodermis?
• Subcutaneous layer deep to the skin
• Composed of adipose and areolar
connective tissue
• Fatty Layer
What three pigments contribute to
skin color
What three pigments contribute to
skin color?
– Melanin – yellow to reddish-brown to black
pigment, responsible for dark skin colors
• Freckles and pigmented moles – result from local
accumulations of melanin
– Carotene – yellow to orange pigment, most
obvious in the palms and soles of the feet
– Hemoglobin – reddish pigment responsible
for the pinkish hue of the skin
What’s the function of sweat glands?
What’s the function of sweat glands?
Different types prevent overheating of the
body; secrete cerumen and milk
Describe Eccrine Sweat Glands?
Describe Eccrine Sweat Glands?
found in palms, soles of the feet, and forehead
Describe Apocrine sweat glands
Describe Apocrine sweat glands
found in axillary and anogenital areas
(arm pits, areola of nipples, and genitals)
Describe Ceruminous glands
Describe Ceruminous glands
modified apocrine glands in external ear
canal that secrete cerumen
Describe Mammary glands
specialized sweat glands that secrete milk
Glands
Describe Sebaceous Glands
Describe Sebaceous Glands
• Simple alveolar glands found all over the body
• Soften skin when stimulated by hormones
• Secrete an oily secretion called sebum
Describe Hair
Describe Hair
• Filamentous strands of dead keratinized
cells produced by hair follicles
• Contains hard keratin
• Pigmented by melanocytes at the base of
the hair
Functions of hair include
Functions of hair include
– Helping to maintain warmth
– Alerting the body to presence of insects on
the skin
– Guarding the scalp against physical trauma,
heat loss, and sunlight
Hair is distributed over the entire
skin surface except:
Hair is distributed over the entire
skin surface except:
– Palms, soles, and lips
– Nipples and portions of the external genitalia
What is Vellus Hair?
What is Vellus Hair?
pale, fine body hair found in children and
the adult female
What is Terminal hair?
What is Terminal hair?
coarse, long hair of eyebrows, scalp, axillary,
and pubic regions
Describe Hair thinning and balding
Describe Hair thinning and balding
• Alopecia – hair thinning in both sexes
• True, or frank, baldness
– Genetically determined and sex-influenced
condition
– Male pattern baldness – caused by follicular
response to DHT
Structure of a Nail
Functions of the Integumentary
System
Functions of the Integumentary
System
• Protection
• Body temperature regulation
• Cutaneous sensation
• Metabolic functions
• Blood reservoir
• Excretion
What does the skin protect from?
What does the skin protect from?
chemical, physical, and mechanical barrier
How is Body Temperature is
accomplished?
How is Body Temperature is
accomplished?
– Dilation (cooling) and constriction (warming)
of dermal vessels
– Increasing sweat gland secretions to cool the
body
Explain Cutaneous Sensation
Explain Cutaneous Sensation
exoreceptors sense touch and pain
Describe Metabolic Functions
Describe Metabolic Functions
Synthesis of vitamin D in dermal blood
vessels
Describe the Blood Reservoir
function of the skin
Describe the Blood Reservoir
function of the skin
skin blood vessels store up to 5% of the
body’s blood volume
What does the skin Excrete?
What does the skin Excrete?
limited amounts of nitrogenous wastes are
eliminated from the body in sweat
Briefly describe Skin Canser
Briefly describe Skin Canser
• Most skin tumors are benign and do not
metastasize
• A crucial risk factor for non-melanoma skin
cancers is the disabling of the p53 gene
• Newly developed skin lotions can fix
damaged DNA
What are the 3 major types of skin
cancer?
What are the 3 major types of skin
cancer?
– Basal cell carcinoma
– Squamous cell carcinoma
– Melanoma
Describe Basal Cell Carcinoma
Describe Basal Cell Carcinoma
• Least malignant and most common skin
cancer
• Stratum basale cells proliferate and invade
the dermis and hypodermis
• Slow growing and do not often metastasize
• Can be cured by surgical excision in 99% of
the cases
Describe Squamous Cell
Carcinoma
Describe Squamous Cell
Carcinoma
• Arises from keratinocytes of stratum spinosum
• Arise most often on scalp, ears, and lower lip
• Grows rapidly and metastasizes if not removed
• Prognosis is good if treated by radiation
therapy or removed surgically
Describe Melanoma
Describe Melanoma
Cancer of melanocytes is the most
dangerous type of skin cancer because
it is:
– Highly metastatic
– Resistant to chemotherapy
• Chance of survival is poor if the lesion is
over 4 mm thick
Skin cancers
What characteristics does
Melanoma Have?
What characteristics does
Melanoma Have?
(ABCD rule)
– A: Asymmetry; the two sides of the pigmented
area do not match
– B: Border is irregular and exhibits indentations
– C: Color (pigmented area) is black, brown,
tan, and sometimes red or blue
– D: Diameter is larger than 6 mm (size of a
pencil eraser)
Describe a First Degree Burn
Describe a First Degree Burn
only the epidermis is damaged
– Symptoms include localized redness,
swelling, and pain
Describe a Second Degree Burn
Describe a Second Degree Burn
Epidermis and upper regions of dermis
are damaged
– Symptoms mimic first degree burns, but
blisters also appear
Describe a Third Degree Burn
Entire thickness of the skin is damaged
– Symptoms: Burned area appears graywhite, cherry red, or black; there is no
initial edema or pain (since nerve
endings are destroyed)
What does the Rule of Nines
estimate?
What does the Rule of Nines
estimate?
• Estimates the severity of burns
• Burns considered critical if:
– Over 25% of the body has second-degree
burns
– Over 10% of the body has third-degree burns
– There are third-degree burns on face, hands,
or feet
Rule of Nines
Explain Fetal Skin Development
Explain Fetal Skin Development
• Epidermis develops from ectoderm
• Dermis and hypodermis develop from mesoderm
• Lanugo – downy coat of delicate hairs covering the
fetus
• Vernix caseosa – substance produced by
sebaceous glands that protects the skin of the fetus
in the amnion
Describe skin development
(Adolescent – Adult)
Describe skin development
(Adolescent – Adult)
• Skin and hair become oilier and acne may
appear
• Skin shows the effects of cumulative
environmental assaults around age 30
• Scaling and dermatitis become more
common
Describe skin development
(old-age)
Describe skin development
(old-age)
• Epidermal replacement of cells slows and skin becomes
thinner
• Skin becomes dry and itchy
• Subcutaneous fat layer diminishes, leading to intolerance
of cold
• Decreased elasticity and loss of subcutaneous tissue
leads to wrinkles
• Decreased numbers of melanocytes and Langerhans’
cells increase the risk of skin cancer
Questions from the Textbook and
Lab Homework
What type of granules are extruded
from the kerationocytes prevent
water loss by diffusion through the
epidermis?
What type of granules are
extruded from the kerationocytes
prevent water loss by diffusion
through the epidermis?
Lamellated
What produces the fibers in
the dermis?
What produces the fibers in
the dermis?
Fibroblast
What type of glands respond
to rising androgen levels?
What type of glands respond
to rising androgen levels?
Apocrine glands
Phagocytic cells that occupy
the epidermis are called?
Phagocytic cells that occupy
the epidermis are called?
Langerhan’s Cells
A unique touch receptor formed
from a stratum basale cell and
nerve fiber is a …..
A unique touch receptor formed
from a stratum basale cell and
nerve fiber is a …..
Merkel disc
What layer is present in thick
skin but not in thin skin?
What layer is present in thick
skin but not in thin skin?
Stratum Lucidum
What cell-to-cell structures hold
the cells of the stratum spinosum
tightly together?
What cell-to-cell structures hold
the cells of the stratum spinosum
tightly together?
Desmosomes
What substance is manufactured
in the skin that plays a role in
calcium absorption in the body?
What substance is manufactured
in the skin that plays a role in
calcium absorption in the body?
Vitamin D
Which epidermal cell type is
most numerous?
Which epidermal cell type is
most numerous?
Keratinocyte
which cell functions as part of
the immune system
which cell functions as part of
the immune system
An epidermal dendritic cell
the epidermis provides a physical
barrier due largely to the
presence of
the epidermis provides a physical
barrier due largely to the
presence of
Collagen
skin color is determined by
skin color is determined by
-the amount of blood
-pigments
-oxygenation level
the sensations of touch and
pressure are picked up by
receptors located in
the sensations of touch and
pressure are picked up by
receptors located in
The stratum spinosum
Skin surface markings that reflect
points of tight dermal attachment
to underlining tissues are called?
Skin surface markings that reflect
points of tight dermal attachment
to underlining tissues are called?
Flexure Lines