Chapter 5:The Integumentary System Flashcards
How many regions make up the skin?
3
- Epidermis
- Dermis
- Hypodermis
What is the epidermis?
outermost superficial region of skin
What is the dermis?
the middle region of the skin
What is the hypodermis?
the deepest region of the skin
what is another name for the hypodermis?
superficial fascia
what is superficial fascia?
the hypodermis
What is the epidermis comprised of?
keratinized stratified squamous epithelium, with 4 cell types and 4 to 5 layers
What cell types are found int the epidermis?
keratinocytes
melanocytes
Merkel cells
Langerhans’ cells
What is the function of the epidermis?
it is the outer portion of the skin, is exposed to the external environment and functions in protection
Keratinocytes
– produce the fibrous protein keratin.
Melanocytes
– produce the brown pigment melanin.
Langerhans’ cells
epidermal macrophages that help activate the immune system.
Merkel cells
function as touch receptors in association with sensory nerve endings.
What are the layers of the epidermis?
Stratum corneum Stratum Lucidum Stratum granulosum Stratum spinosum Stratum basale
What is the stratum basale?
the basal layer of the epidermis. the deepest layer, firmly attached to the dermis
What is the stratum basale made of?
a single row of the youngest keratinocytes
what happens in the stratum basale?
cells undergo rapid division, hence its alternate name, stratum germinativum
What is the stratum spinosum?
the prickly layer of the epidermis. 2nd from the bottom
What is the stratum spinosum made of?
- cells contain weblike system of intermediate filaments attached to desmosomes.
- melanin granules and Langerhans’ cells are abundant in this layer
What is the stratum granulosum?
the granular layer, 2nd from the top
what does the stratum granulosum look like?
thin; three to five cell layers in which drastic changes in keratinocyte appearance occurs
What accumulates in the stratum granulosum?
Keratohyaline and lamellated granules
What is the stratum lucidum?
a clear layer, found only in thick skin. superficial to the stratum granulosum
What is the stratum lucidum made of?
a few rows of flat, dead keratinocytes
What is the stratum corneum?
the horny layer, the outermost layer
What percent of the epidermis is made of the stratum corneum?
3/4
What are the functions of the stratum corneum?
- waterproofing
- Protection from abrasion and penetration
- Rendering the body relatively insensitive to biological, chemical, and physical assaults
What is the dermis?
the second major skin region containing strong, flexible connective tissue
What cell types are in the dermis?
fibroblasts, macrophages, and occasionally mast cells and white blood cells
What is the dermis composed of?
2 layers - papillary and reitcular
Papillary layer
- -in the dermis—
1. areolar connective tissue with collagen and elastic fibers
2. its superior surface contains peg-like projections called dermal papillae
3. dermal papillae contain capillary loops, Meissner’s corpuscles, and free nerve endings
What does dermal papillae contain?
capillary loops
Meissner’s corpuscles
free nerve endings
What is the Reticular Layer?
a layer of the dermis
accounts for about 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 do collagen fibers do for the reticular layer?
add strength and resiliency to the skin
what do elastin fibers do for the reticular layer?
provide stretch-recoil properties
what is the hypodermis?
subcutaneous layer deep to the skin
composed of adipose and areolar connective tissue
what is the hypodermis composed of?
adipose and areolar connective tissue
What determines skin color?
3 pigments
Melanin
Carotene
Hemoglobin
Melanin
yellow to reddish-brown to black pigment, responsible for dark skin colors
- freckles and pigmented moles result from local accumulations of melanin
what causes freckles and pigmented moles?
local accumulations of melanin
carotene
yellow to orange pigment, most, most obvious in the palms and soles of the feet
hemoglobin - in skin
reddish pigment responsible for the pinkish hue of the skin
what do sweat glands do?
- prevent overheating of the body
- secrete cerumen (earwax)
- produce milk
what kind of sweat glands are there?
Eccrine sweat glands - found in palms, soles of the foot, and forehead
Apocrine sweat glands - found in axillary and anogential areas
Ceruminous glands - modified apocrine glands in external ear canal that secrete cerumen
Mammary glands - specialized sweat glands that secrete milk
what are sebaceous glands?
simple alveolar glands found all over the body
what do sebaceous glands do?
soften skin when stimulated by hormones
secrete an oily secretion called sebum
What is hair?
filamentous strands of dead keratinized cells produced by hair follicles
what does hair contain?
hard keratin which is tougher and more durable than soft keratin of the skin
names of parts of hair in skin and out of skin
the shaft projecting from the skin and the root embedded in the skin
parts of the hair from deep to superficial
core (medulla)
cortex
outermost cuticle
what determines the color of hair
hair is pigmented by melanocytes at the base of the hair
What is the function of hair?
- help maintain warmth
- alerting the body to presence of insects on the skin
- guarding the scalp against physical trauma, heat loss, and sunlight
how is hair distributed?
over the entire skin surface except
- palms, soles, and lips
- nipples and portions of the external genitalia
what is the hair follicle?
root sheath extending from the epidermal surface into the dermis
what does the deep end of the hair follicle form?
it expands to form a hair bulb
hair bulb
deep end of the hair follicle. it is wrapped in a knot of sensory nerve endings (root hair plexus)
what happens when our hair moves?
it stimulates the nerve endings (root hair plexus) - our hairs act as sensitive touch receptors
Types of hair
- Vellus - pale, fine body hair found in children and the adult female
- Terminal - coarse, long hair of eyebrows, scalp, axillary, and pubic regions
Types of hair thinning and baldness
Alopecia - hair thinning in both sexes
True, or frank, baldness
1. genetically determined and sex-influenced condition
2. male pattern baldness - caused by follicular response to DHT
Structure of the nail
scalelike modification of the epidermis on the distal, dorsal surface of fingers and toes
Functions of the integumentary system
- Protection - chemical, physical, and mechanical barrier
- Body temp regulation
- Cutaneous sensation - exoreceptors sense touch and pain
- Metabolic functions - vit D synthesis in dermal vessels
- Blood reservoir - skin blood vessels store up to 5% of the body’s blood volume
- Excretion - small amount of nitrogenous waste (in sweat)
how is body temperature regulation accomplished
- dilation (cooling) and constriction (warming) of dermal vessels
- increasing sweat gland secretions to cool the body
Skin Cancer - most tumors are
benign and do not metastisize
what is a crucial risk factor for nonmelanoma skin cancers?
disabling of the P53 gene
newly developed skin lotions can
fix damaged DNA (skin cancer)
3 major types of skin cancer
- Basal cell carcinoma
- Squamous cell carcinoma
- Melanoma
Basal cell carcinoma - seriousness and occurance
least malignant, most common form of skin cancer
Basal cell carcinoma - how does it happen?
Stratum basale cells proliferate and invade the dermis and hypodermis
how fast do basal cell carcinomas grow?
slowly, and do not often mteastisize
how are basal cell carcinomas dealt with?
can be cured by surgical excision 99% of the cases
Squamous cell carcinoma - arises from____. Where?
keratinocytes of stratum spinosum.
most often on scalp, ears, and lower lip
Squamous cell carcinoma - how fast does it grow?
grows rapidly and metastisizes if not removed
Prognosis for squamous cell carcinoma?
good if treated by radiation therapy or removed surgically
Melanoma - seriousness?
most dangerous because
- highly metastatic
- resistant to chemotherapy
Characteristics of Melanoma
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 6mm (size of a pencil eraser)
How is melanoma treated?
wide surgical excision accompanied by immunotherapy
Prognosis for melanoma?
chance of survival is poor if the lesion is over 4mm thick
Burns - degrees
1st - only the epidermis is damaged
2nd - epidermis and upper regions of dermis are damaged
3rd - entire thickness of the skin is damaged
First degree burn symptoms
localized redness, swelling, pain
Second degree burn symptoms
mimic first degree burns, but blisters also appear
Third degree burn symptoms
Burned area appears gray-white, cherry red, or black; there is no initial edema or pain (since nerve endings are destroyed).
Rule of Nines - what for?
estimates the severity of burns.
considered critical if:
- Over 25% of the body has 2nd degree burns
- over 10% of the body has 3rd degree burns
- there are 3rd degree burns on face, hands, or feet
the epidermis develops from
ectoderm
dermis and hypodermis develop from
mesoderm
what is lanugo?
downy coat of delicate hairs covering the fetus
what is the vernix caseosa
substance produced by sebaceous glands that protects the skin of the fetus in the amnion
skin as adolescent to adult
skin and hair become oilier and acne may appear
when does the skin show the effects of cumulative environmental assaults
around age 30
what become more common with the skin as we age into adulthood
scaling and dermatitis
what happens to our skin as we get old?
- 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.
What does keratin do?
It makes skin strong and resilient.
Which cells are pressure sensors?
Merkel cells
What are the layers of the epidermis?
Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale
what are the regions of the skin?
Epidermis
Dermis
Hypodermis
Where are the newest epidermal cells?
deepest - stratum basale
where are the oldest epidermal cells
most superficial - stratum corneum
what layer determines skin color?
Stratum spinosum
what do the cells in the stratum granulosum look like?
flattened and hardened
what layer of skin is more common in men? Why?
Stratum lucidum - b/c their skin is thicker
where is there blood supply, nerve endings, and hair follicles?
in the dermis
What are Meissner’s corpuscles?
nerve endings
which layer of the dermis is thicker?
the reticular layer
how much does each foot sweat in a day?
1 c per foot
What are the layers of a hair follicle - deep to superficial - cross section
Medulla Cortex Cuticle Internal epithelial root sheath external epithelial root sheath Glassy membrane Connective tissue root sheath
What makes up the follicle wall of a hair follicle?
Connective tissue root sheath
Glassy membrane
External epithelial root sheath
Internal epithelial root sheath
What makes up the hair root?
cuticle
cortex
medulla
