Download Integumentary System

Integumentary System
The skin and its accessory
organs, such as hair, nails,
glands, and specialized receptors,
constitute the integumentary
system.
Skin
• Organ: Group of tissues working
together to perform a common,
specialized function. Skin and its
accessory organs (hair, nails, glands,
receptors) are considered the
integumentary system.
Dermatology
• Branch of medicine dealing with the
diagnosis and treatment of skin
disorders.
Factors affecting appearance of
skin
a. nutrition
b. hygiene
c. circulation
d. age
e. immunity (allergy)
f. genetic traits
g. psychological states
h. drugs
i. sun
j. smoking (wrinkles and vasodilation)
Structure
1. Outer epidermis (predominantly
epithelial tissue).
2. Inner dermis (connective tissue layer).
3. Subcutaneous layer: attaches skin to
underlying structures (adipose and
connective tissue).
Structure
•
Functions
1. Regulation of body temperature (sweat, shunting
of blood).
2. Protection: physical barrier (microbes,
dehydration, UV light).
3. Sensation: temperature, touch, pressure, pain.
4. Excretion: water, salt, urea, other organic
compounds.
5. Immunity: nonspecific immunity (ie: physical
protection). Langerhans cells of the epidermis
destroy foreign invaders.
6. Synthesis of Vitamin D: via UV light. Vitamin D
helps absorption of calcium and phosphorus from
digestive system into the blood.
Epidermis
4 cell types:
•
•
•
•
Keratinocytes
Melanocytes
Langerhans Cells
Merkel’s cells.
Keratinocytes
• produce keratin (water proofing protein).
Protects underlying
tissues from light,
heat, bacteria, chemicals.
Nucleus and
organelles
degenerate
and cell dies
(becomes dead
package of keratin).
Melanocytes
• produces melanin, a pigment which
absorbs UV light radiation.
Langerhans Cells
• immune
functioning
cells
Merkel’s cells
• epithelial cells in Merkel’s discs
(receptors) that are sensitive to
touch
Layers (from deepest to the
surface)
•
•
•
•
•
Stratum basale
Stratum Spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
Epidermis
•
Epidermis - layers
• a. Stratum basale: regenerative cells
and melanocytes. Single layer of
cuboidal or columnar epithelial cells.
Termed basal epithelial stem cells
• b. Stratum Spinosum: about 10 layers of
cells (thick layer). Cells have "spinelike"
projections that interlock and confer
strength to the skin.
Epidermis - layers
• c. Stratum granulosum: thin layer of
granulated cells (keratohyalin).
• d. Stratum lucidum: layer in thick skin
only (palms of hands, soles of feet).
• e. Stratum corneum: 15-30 layers of
highly keratinized cells that are
sloughed off and replaced. Protect from
light, dehydration, heat, trauma,
bacteria).
Dermis
• Predominantly connective tissue. Thick and thin in
different body regions. Few cells (adipocytes,
fibroblasts, macrophages). Collagen and elastic
fibers confer extensibility and elasticity.
Predominantly connective tissue. Thick and thin in
different body regions. Few cells (adipocytes,
fibroblasts, macrophages). Collagen and elastic
fibers confer extensibility and elasticity.
Receptors:
• a. Meissner’s corpuscles: nerve endings sensitive to
light touch.
• b. Pacinian corpuscles: receptors for pressure
(sustained touch).
Dermis
• 4. Hair follicles, nerves, sebaceous (oil)
glands, sudoriferous (sweat) glands.
• 5. Blood vessels (arteries and veins)
and lymphatics.
• 6. Dermal papillae project up into
epidermal ridges and create ridges on
skin to help us grip things (fingerprints).
Striae (stretch marks)
• Combination of collagen
and elastic fibers gives the
skin estensibility and
elasticity. Extreme
stretching may produce
small tears in the dermis
causing striae.
Fingerprints
• During fetal development the basal layer
begins to grow faster than either the
epidermis or dermis in the tips of the
finger. This leads to an increased stress in
the basal layer, which causes it to buckle
inwards, creating ridges on the surface of
the skin.
Subcutaneous layer
(Hypodermis)
•
Subcutaneous layer (Hypodermis)
• A. Location: Between dermis and
underlying bone or muscle.
• B. Structure: Composed of areolar
connective tissue, many blood vessels,
adipose tissue, and nerves.
• C. Function: Provides cushioning,
protection, insulation, energy reserve.
Attaches skin to underlying structures.
Skin Color
A. Due to melanin, carotene, and hemoglobin.
The amount of melanin determines the
darkness of the skin.
B. Melanin confers a brownish tint to the skin.
Carotene confers a yellow-orange color.
Hemoglobin confers a pink to reddish color to
the skin. An inherited inability of an individual of
any race to produce melanin results in albinism
(no pigment in hair, eyes, or skin. All races have
about the same amount of melanocytes, thus
variations in skin color are due to amount of
pigment they produce. Freckles result from
patches of melanin.
• Malignant melanoma: cancer of the
melanocytes. Fast growing, dangerous
cancer.
Accessory Organs
• Hair
• Glands
-Sebaceous
- Sudoriferous
- Ceruminous
• Nails
Hair
1. Outgrowths of the epidermis.
2. Functions:
a. protects from sun rays (UV light).
b. insulates.
c. provides sensitivity.
d. eyelashes and eyebrows protect eyes
from foreign particles.
e. nasal hairs protect from inhaled
foreign substances.
Hair
• Hair is
composed of
strong
structural
protein called
keratin. This is
the same kind
of protein that
makes up the
nails and the
outer layer of
skin.
Hair Structure
•
•
•
•
a. Shaft: external, exposed portion of hair
b. Root: portion below surface in dermis of skin
c. Follicle:
- External sheath and internal sheath of
epidermal cells covered by a connective tissue
sheath.
• - follicle surrounded by nerve ending: sensitive
to hair movement
• d. Bulb: contains papilla of hair which contains
blood vessels for growing hair nourishment, and
the matrix where new hair cells are derived
from. Melanocytes of matrix produce melanin for
hair coloring.
Hair Structure
• Growth rate of hair affected by illness,
radiation therapy, chemotherapy,
nutrition, age, stress, genetics, and
gender.
• Arrector pili muscles (smooth) contract
to pull hair erect. Results in “goose
bumps”. Provides some insulation when
cold, warning when frightened.
Glands - Sebaceous (oil)
glands:
• a. connected to hair follicles or open
directly to skin’s surface.
• b. no sebaceous glands on palms of
hands or soles of feet.
• c. secrete sebum that prevents hair from
drying out, dessication of skin, bacterial
growth.
• d. Pimple, blackhead: build-up of oil and
bacteria in a sebaceous gland.
•
Sudoriferous (sweat) glands:
a. produce perspiration (sweat).
b. perspiration evaporates allowing heat
to be lost; excretes some wastes.
• Two types:
Eccrine – since birth
Apocrine – Puberty – same components
+ lipids and proteins
Ceruminous (wax) glands
• a. located in the outer ear canal.
• b. combined secretions of ceruminous
and sebaceous glands is termed
cerumen. Cerumen and hairs of the
outer ear canal provide a sticky barrier
against foreign invaders.
Nails
1. plates of tightly packed, hard, keratinized
cells of the epidermis.
2. grow about 1mm per
week.
3. help to grasp and
manipulate small
objects; provide
protection for the
ends of the digits;
scratch an itch.
Common Disorders - Burns
• 1. First degree: minor damage to the
epidermis only with no blistering.
• 2. Second degree: involves both
epidermis and dermis. Redness,
blistering, edema, and pain.
• 3. Third degree: most severe burns.
Burns through dermis to subcutaneous
layer, or deeper. Destroys epidermis,
dermis, and epidermal organs, and skin
functions are lost.
Burns
•
First
second
third
Pressure Sores: bedsores.
• Constant deficiency of blood to tissues
over bony projections that have been
subjected to prolonged pressure
against an object like
a bed, cast, or splint.
Sunburns
• Burns due to
overexposure
to UV light.