Download Integumentary system - Mrs. Avila`s Science Class

BODY MEMBRANES
AND SKIN
Body Membranes

Function of body membranes
◦ Line or cover body surface
◦ Protects body surfaces
◦ Lubricate body surfaces
Classification of Body Membranes
 Epithelial membranes (3 types)
1. Cutaneous membrane (skin)
•
A dry membrane
•
Outermost protective boundary
•
Primary organ of the integumentary
2. Mucous membrane
•
Lines and protects organs that open to the
exterior of the body
•
Found lining ducts and passageway of the
respiratory and digestive tracts
•
Adapted for absorption or secretion
Classification of Body Membranes
3. Serous membrane- lines body cavities and
some organs that are not open to the
external environment.
•
Parietal membrane- lines body cavities (wall
paper)
•
Visceral membrane- covers the viscera(organs)
•
Important Serous Membranes
•
Pleura- surrounds a lung and lines the thoracic
cavity
•
Peritonium- covers the abdominal viscera and lines
the abdominal cavity
•
Pericardium- covers the heart
Classification of Body Membranes
 Connective membranes
• Do not contain epithelial components
• Synovial membranes- lines the spaces
between bone in joints
• Have smooth and slick membranes
that secret synovial fluid.
• Reduces friction
It’s Skin Deep:
THE INTEGUMENTARY
SYSTEM
Dermatology Down Deep

Dermotology: the branch of medicine
dealing with the skin and its diseases,a
unique specialty with both medical and
surgical aspects.

A dermatologist takes care of diseases, in
the widest sense, and some cosmetic
problems of the skin, scalp, hair, and nails.
Integumentary System

Skin (cutaneous membrane)

Skin derivatives
 Sweat glands
 Oil glands
 Hairs
 Nails
© Matt Dillard 2012
Layers of the skin
Two main Layers
 Epidermis – outer layer
 Stratified squamous epithelium
 Often keratinized (hardened by keratin)
 Dermis
 Dense connective
tissue
Other Layers
 Dermoepidermal junction - connects
the epidermis and dermis
 Deep to dermis is the hypodermis
 Not part of the skin
 Anchors skin to underlying organs
 Composed mostly of adipose tissue
 Also called the subcutaneous layer or
superficial fascia
 Thick and Thin Skin
Cells and Layers of
Epidermis: Don’t judge this
book by its cover.
Cells in the Epidermis
• Keratinocytes– produce the fibrous protein
keratin.
• Constitute more than 90% of cells present; principal
structural element of the outer skin;
• Undergo keratinization (cells lose their nucleus)
• Keratin hardens and flattens the cells as they move
outward and it waterproofs the skin.
Photograph by Andrew Syred/Science Photo Library
Cells in the Epidermis

Melanocytes- pigment-producing cells
(melanin) (5% of the total); contribute to skin
color and filter ultraviolet (UV) light
Cells in the Epidermis

Epidermal dendritic
cells- branched antigen
presenting cells; play a
role in activating immune
response; also called
Langerhans cells.

Merkel cells – function
as touch/tactile cells
attach to sensory nerve
endings to form “light
touch” receptors
Layers of the Epidermis

Stratum corneum (horny)
◦ Most superficial layer, dead cells filled
with keratin
◦ Barrier area

Stratum lucidum (clear layer)
◦ cells filled with keratin precursors
called eleidin; absent in thin skin.

Stratum granulosum (granular
layer)
◦ Cells arranged in two to four layers
and filled with keratohyalin
◦ Contains high levels of lysosomal
enzymes
Layers of the Epidermis

Stratum germinativum (growth
layer)
◦ Stratum spinosum (spiny layer)
 Cells arranged in 8-10 layers made
of desmosomes
 Rich in RNA
◦ Stratum basale (base layer)
 Single layer of columnar cells.
 Only cells undergo mitosis
 Migrate to the top and shed
Dermoepidermal junction

A basement membrane with unique
fibrous elements and a polysaccharide
gel “glue” the epidermis to the dermis
below

The junction is a partial barrier to the
passage of some cells and large
molecules
Dermis: More Than Skin Deep

Sometimes called “true skin”—much thicker than the
epidermis and lies beneath it.

Gives strength to the skin

Serves as a reservoir storage area for water and
electrolytes Contains various structures
◦ Arrector pili muscles and hair follicles (Figure 6-5)
◦ Sensory receptors (Figure 6-6)
◦ Sweat and sebaceous glands
◦ Blood vessels

Rich vascular supply plays a critical role in
temperature regulation
Dermis: More Than Skin Deep
Two layers
 Papillary layer
o Projections called dermal papillae
o Pain receptors
o Capillary loops
o Joins with the dermoepidermal junction to form
finger prints.
 Reticular layer ( 80%)
o Blood vessels
o Glands
o Nerve receptors
o White collagenous fibers in this layer combine with
elastics making skin tough yet stretchable (leather)
Dermal Growth and Repair
The dermis does not continually shed
and regenerate itself as does the
epidermis.
 Fibroblast form new connective fiber
 Scaring occurs

Normal Skin Color Determinants
 Melanin
o Yellow, brown or black pigments caused by melanin.
o Amount of melanin produced depends upon genetic
and exposure to sunlight
 Carotene
o Orange-yellow pigment from some vegetables
o usually hidden by the effects of melanin. Asians have
little melanin which allows the yellow to show more
than other nationalities.
 Hemoglobin
o Red coloring from blood cells in dermis capillaries
o Oxygen content determines the extent of red
coloring
Other Pigments in Skin

Pinkish color
o seen in fair-skinned persons because the vascular
dermis is visible.

Cyanosis
 blue look to skin due to poorly oxygenated blood

Blushing
o caused by dilation of blood vessels

Pale by fright
o caused by restriction of vessels
Your turn to research

Harry can have any type of skin cancer.
Study the structures of the skin to best
determine if Harry has developed skin
cancer.
Malfunctioning Melanocytes




Albinism – melanocytes completely fail to
secrete melanin. Hair, skin, and iris are white.
Vitiligo – loss of pigment in certain areas of
the skin producing white patches.
Freckles and moles are formed when
melanin becomes concentrated in local areas.
Malignant melanoma – a cancerous
change in a mole that may metastasize
(spread) rapidly and is most difficult to treat.
Exposure to sunlight increases risk.
Response to Disease
Jaundice – caused when bilirubin is deposited
in skin because a diseased liver is unable to
excrete this pigment
 Skin may appear bronzed due to the
deposit of excess melanin when a person’s
adrenal gland is functioning poorly.
 A bruise indicates that blood has escaped
from the blood vessels and has clotted under
the skin.
 Over eating carotene-rich vegetables such
as carrots may cause skin to have a yellow tint.

Skin Physiology

Protects deeper tissues from:
 Mechanical damage
 Chemical damage
 Bacterial damage
 Thermal damage
 Ultraviolet radiation
 Desiccation
Skin Function

Aids in heat regulation

Acts as a somatic sensory receptors

Movement with out injury

Aids in excretion of urea and uric acid

Synthesizes vitamin D
Homeostasis of body temperature

Heat loss: approximately 80% of heat loss occurs through the
skin; remaining 20% occurs through the mucosa of the
respiratory, digestive, and urinary tracts (Figure 6-15)
◦ Evaporation: to evaporate any fluid, heat energy must be expended;
this method of heat loss is especially important at high environmental
temperatures when it is the only method heat can be lost from the skin
◦ Radiation: transfer of heat from one object to another without actual
contact; important method of heat loss in cool environmental
temperatures
◦ Conduction: transfer of heat to any substance in contact with the
body; accounts for relatively small amounts of heat loss
◦ Convection: transfer of heat away from a surface by movement of air;
usually accounts for a small amount of heat loss
Skin Homeostatic Imbalance

Infections
 Athletes foot
 Caused by fungal infection
 Boils and carbuncles
 Caused by bacterial infection
 Cold sores
 Caused by virus
Skin Homeostatic Imbalance
•
Infections and allergies
• Contact dermatitis
• Exposures cause allergic reaction
• Impetigo
• Caused by bacterial infection
• Psoriasis
• Cause is unknown
• Triggered by trauma, infection, stress
Athlete’s Foot
Boils
Cold Sores
Impetigo
Psoriasis
Burns
 Tissue
damage and cell death caused
by heat, electricity, UV radiation, or
chemicals
 Associated
dangers
Dehydration
Electrolyte imbalance
Circulatory shock
Severity of Burn
Determined depth of lesion and percent
of body surface
 “Rule of Palm”- Palm size of burnt victim
is 1%
 “Rule of Nine”- body is divided into areas
of 9%

 First-degree burns
 Only epidermis is damaged
 Skin is red and swollen
 Second degree burns
 Epidermis and upper
dermis are damaged
 Skin is red with blisters
 Third-degree burns
 Destroys entire skin layer
 Burn is gray-white or black
Critical burns

Burns are considered critical if:
 Over 25% of body has second degree
burns
 Over 10% of the body has third degree
burns
 There are third degree burns of the face,
hands, or feet
Skin Cancer

Cancer – abnormal cell mass

Two types
 Benign
 Does not spread (encapsulated)
 Malignant
 Metastasized (moves) to other parts of
the body
 Skin cancer is the most common type of
cancer
Skin Cancer Types
 Basal cell carcinoma
 Least malignant
 Most common type
 Arises from statum basale
 Squamous cell carcinoma
 Arises from stratum spinosum
 Metastasizes to lymph nodes
 Early removal allows a good chance of cure
Skin Cancer Types
 Malignant melanoma
 Most deadly of skin cancers
 Cancer of melanocytes
 Metastasizes rapidly to lymph and blood
vessels
 Detection uses ABCD rule
ABCD Rule
 A = Asymmetry
 Two sides of pigmented mole do not
match
 B = Border irregularity
 Borders of mole are not smooth
 C = Color
 Different colors in pigmented area
 D = Diameter
 Spot is larger then 6 mm in diameter
Skin Structures
Appendage of the Skin: Glands

Sebaceous glands (all over except palms
and soles of feet)
 Produce oil
 Lubricant for skin
 Kills bacteria
 Most with ducts that empty into hair follicles
 Glands are activated at puberty
 Acne – active infection of sebaceous glands
Appendages of the Skin: Glands

Sweat glands- Widely distributed in
skin
◦ Eccrine- Open via duct to pore on skin
surface
◦ Apocrine- Ducts empty into hair follicles

Ceraminous- secrets cerumen (wax)
and protects against dehydration
Sweat and its Function

Composition
◦ Mostly water
◦ Some metabolic waste
◦ Fatty acids and proteins (apocrine only)

Function
◦ Helps dissipate excess heat
◦ Excretes waste products
◦ Acidic nature inhibits bacteria growth

Odor is from associated bacteria
Appendages of the Skin: Hair

Dead keratinized cells

Types
◦ Vellus – pale, fine body hair
found in children and the adult
female
◦ Terminal – coarse, long hair of
eyebrows, scalp, axillary, and
pubic regions

Produced in the epidermis
Hair Function and Distribution

Functions
◦ 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
◦ Palms, soles, and lips
◦ Nipples and portions of the external genitalia
Hair structure
Papillae- cluster of capillaries
 Root part of the hair embedded in dermis


Shaft- visible part of hair
◦ Round – straight hair
◦ Oval- wavy hair
◦ Flat- curly or kinky hair

Core
◦ Medulla- inner core
◦ Cortex outer portion

Root hair plexus- knot of sensory nerve endings
Hair Follicle
Hair Thinning and Baldness
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
Appendages of the Skin: Nails
 Consist of epidermal cells converted to
hard keratin.
 Lack of pigment makes them colorless
Nail Structures

Free edge

Body- visible part

Root of nail- part of nail hidden by
the fold of skin (cuticle)

Lunula- moon shaped root area near
root

Nail bed- epithelium under nail
Figure 4.9