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Chapter 5: Skin and the Integumentary Membrane (Skin and it's tissues…
Chapter 5: Skin and the Integumentary Membrane
Skin and it's tissues (Cutaneous membrane)
A.
General Structure:
Two distinct regions or layers compose the skin:
a.
Epidermis = outermost layer;
keratinized stratified squamous ET.
b.
Dermis = inner layer;
keratinized epithelium (hair follicles),
glandular epithelium (sweat, sebaceous glands),
dense irregular CT (collagen),
smooth muscle tissue (arrector pili muscles),
nervous tissue (Meissner"s & Pacinian Corpuscles), and
blood vessels.
Subcutaneous layer = adipose tissue; distinct layer beneath the skin also called hypodermis
B.
Skin Functions
Protection:
Physical barrier
a.
from water loss;
b.
from injury;
c.
from chemicals and microorganisms.
Chemical Barrier
a.
pH or 5-6
b.
prevents microorganism
Biological barrier
a.
Langerhans cells (epidermis)
b.
macrophages and mast cells (dermis)**
Excretion (minimal, most through kidneys)
urea;
uric acid.
Cutaneous Sensation:
Light touch detection = Messner's Corpuscle's;
a.
egg-shaped;
b.
located in dermal papillae;
c.
populate areas in the fingerprints, palms, soles, eyelids, tip of tongue, nipples, clitoris, tip of penis.
Pressure detection = Pacinian Corpuscle's
a.
onion-shaped;
b.
located in deep dermis and subcutaneous regions;
Vitamin D Synthesis
UV rays in sunlight activate its synthesis;
Vitamin D is required for bone homeostasis.
Blood Reservoir:
The dermis houses about 10% of the body's blood vessels.
Skin only requires 1-2% of the body's blood
Immunity:
Langerhan's cells (macrophages);
interact with T-helper cells in immune responces.
5-1
Which of the following is the correct order of the layers of the cutaneous membrane?
epidermis, dermis, hypodermis
The tissue under the skin is called the
hypodermis or subcutaneous layer
As cells are pushed from the deeper portion of the epidermis toward the surface,
they die
The layer of the epidermis at the surface is the
stratum corneum
Thick skin can be found on the
stratum corneum
The skin is also called the
cutaneous membrane
Thin skin is defined by the thickness of the
epidermis
An epidermal layer that produces large amounts of keratin is the
stratum granulosum
Epidermal cells are supplied with nutrients from blood vessels in the
dermis
Drugs suspended in
oils
or
lipid-soluble carriers
can penetrate the epidermis.
Functions of the skin include
regulating body temperature
An individual with excessive epidermal sheddig on the scalp may be prone to develop this condition.
dandruff
The primary mode of the heat loss from the body is
radiation
5.2-5.3
Which of the following is a function of the integumentary system that aids the endocrine system?
synthesis of vitamin D
Epidermal cells synthesize this vitamin when exposed to sunlight.
Vitamin D3
In albinism,
melanin
is lacking.
The skin may turn orange as a result of
keratin
buildup.
The pigment melanin
A and C only
The most important factor in skin color is
genetic factors
Exposure of the skin to ultraviolet light
can stimulate the production of melanin
When a person becomes "pale," what is the physiologic basis?
The number of red melanocytes in the skin increases.
5.4-5.6
The dermis is composed largely of
dense irregular connective tissue.
When smooth muscles in the walls of dermal blood vessels contract,
body heat is conserved.
The layer of the skin that provides themoregulation via changing blood flow is the
dermis.
Folds of the dermis that cause fingerprints are called
dermal papillae.
Nerve fibers in the skin are associated with
smooth muscles, blood vessels, sensory never endings, and hair follicles; all of the above.
When the body is overheated, the skin responds by
increasing blood flow to the dermis.
The subcutaneous layer is made of
loose connective and adipose tissues.
The hypodermis contains mostly
adipose tissue.
Injections made under the skin are called
subcutaneous injections.
Shafts of hair are made by
dead epidermal cells.
When the arrector pili muscles contract, "goose bumps" are formed.
Hairs are shed.
Accessory structures of the skin include
hair follicles, arrector pili muscles, sebaceous glands, and apocrine sweat glands; All of the above.
5.7-5.10
The pale cresent area of the nail is called the
lunula.
The fold of stratum corneum over the base of a nail is called the
cuticle.
The type of burn that may require a skin graft is a
third-degree burn.
A burn that penetrates the epidermis and part of the dermis is classified as a
second degree burn.
Why would an elderly person be more prone to skin infections than a younger person?
All of the above
This type of burn appears inflamed and tender but has no blisters.
first-degree burn
The most severe type of skin cancer is most likely to develop from
melanocytes.
A "rug burn" is an example of an
abrasion
A burn that involves only the epidermis, such as a mild sunburn, is classified as
first degree
Glands that are located in the ear canal are called
ceruminous glands
Perspiration produced by apocrine sweat glands
is limited to the hair follicles of the axilla, nipples, and groin
The condition that results from clogged sebaceous glands is
acne.
Eccrine sweat glands
respond primarily to elevated body temperature.
Sweat helps to cool the body by
evaporation.
Eccrine and sebaceous glands differ in
type of secretion, material secreted, location in the body, their association with hair follicles; All of the above.
The glands that develop at puberty are
apocrine glands.
Specialized sweat glands that produce milk are called
mammary glands.
What are the 5 layers of thick skin?
spinosum, granulosum, lucidum, corneum.
5-1
Epidermis:
Structure = keratinized stratified squamous epithelium
4 distinct layers in the epithelial cells:
Stratum corneum = outermost layers
Stratum lucidum = translucent layer cells separating.
Stratum granulosum = composed of 3-5 layers of flattened granular cells cells.
Stratum spinosum = composed of many layers of spiky cells with large nuclei.
Stratum basale (germinativum) = inner most layer
Main Function = Protection (keratin)
a. prevents moisture loss (waterproof)
b. prevents injury by penetration
c. prevents microorganisms/chemicals entry
Pigment = melanin
produced by melanocytes in stratum basale (germinativum)
5-2
Genetic factors
People of diff races have the same # of melanocytes, but the amount of melanin produced varies (determined by DNA)
Environmental Factors
affect melanin production: by affecting gene expression
Physiologic Factors
may affect skin color (but not melanin production)
5-3
Vitamin D3 (sunlight converts a cholesterol related steroid)
Liver converts into calcitrol
Skin Cancers
Basal cell carcinoma
Squamous cell carcinomas
Malignant Melanoma
Prevention
Avoid mid-day sun, & were sun block
5-4
Dermis = inner layer of skin
:
Two distinct layers:
Papillary layer (20%) is below epidermis:
Composed of loose areolar CT
Reticular layer (80%) = dense irregular CT
bundles of collagen fibers
Main Function = nourishment of epidermis
5-5
Subcutnaeous Layer (hypo dermis) = beneath skin
Structure = adipose tissue and blood vessels
Function = insulation
5-6
Hair follicle
hair root or base in deep dermis
follicle throughout dermis
hair shaft in epidermis
Growth
grows for 2-5 years / new cycle pushes old hair out
Keritiniation
cells are epithelium
Pigment
= melanin decreases with age
Hair Papilla
peg of connective tissue
Arector pili muscle
= a bundle of smooth muscle associated with every hair follicle.
Causes hair to stand on end (goose bumps) when frightened of cold.
5-7
Sebaceous glands
holocrine gland (simple cuboidal epithelium)
Sebum is secreted into hair follicle
Function: sebum keeps skin and hair soft, pliable and virtually waterproof