Transcript Integumentary PP

Integumentary System
The Skin
Facts about the skin
• Skin is the largest external
organ
• 1mm thick when you’re born
• Thickens to 2mm as you
age
• Thins as you reach old age
• Weighs on average between
6-10 lbs
• Soles of your feet and palms
have no hair follicles
• Majority of dust in your
house is made of skin flakes
Integumentary System
Tissues that make up skin
• Epithelium of epidermis
• Connective tissue of dermis(Dense Irregular CT)
• Subcutaneous layer (AKA superficial fascia or
hypodermis)
Skin is the main organ of integumentary system but
also consists of its derivatives
• Hair
• Nails
• Glands
• Nerve endings
Layers of the skin
Functions of the Skin
• Regulation of body
temperature
• Protection
• Sensation
• Excretion
• Immunity
• Blood reservoir
• Vitamin Synthesis
Synthesis of Vitamin D
• An hour of sunlight per week is sufficient to
activate the body's own vitamin D precursor
• The sun triggers cholesterol found in epidermal
cells to convert into Vitamin D
• Vitamin D can also be consumed in fortified
milk.
• Vitamin D is essential because it regulates Ca
and Phosphorus and keeps skeleton strong
• Deficiencies can cause rickets, osteoporosis,
osteomalacia
Components of the skin
Surface Film
• Protective barrier of skin is formed
by a thin film of emulsified
material spread on its surface
• Made out of sweat, sebum and
shed epithelial cells
• Functions
– Protect against irritants
– Antimicrobial
– Lubricate, hydrate
Cell of the Epidermis
Epidermis is avascular and made up of keratinized
stratisfied squamous cells.
Keratinocytes
– make up 90% of epidermal cells
– Principal outer element of the skin
– Become filled with tough fibrous keratin
Melanocytes
– Contribute to color of skin
– Keep UV light from penetrating deep
Langerhans cells
– Play a role in immune defense
– Function with white blood cells
Epidermis
The epidermis is made up of five sub-layers:
•
Basal layer (stratum basale)
The basal layer is the inner layer of the epidermis, containing basal
cells. Basal cells continually divide, forming new keratinocytes and
replacing the old ones that are shed from the skin's surface.
•
Spinous layer (stratum spinosum)
So named because after preservation, tissue looks to have
“spines.” These are desmosomes being formed to connect the
epithelial cells.
•
Granular layer (stratum granulosum)
So named because they appear as grains under magnifications.
Here the cells are beginning to deteriorate as keratin is forming
inside of them. Granules are called keratohyalin.
•
Clear Layer (stratum lucidum)
So named because it is a clear layer of cells as they loose their
cytoplasmic contents and become fully keratinized. Thicker skin
has more of these cells, absent in thin skin.
•
Horny layer (stratum corneum)
This layer contains continually shedding, dead keratinocytes (the
primary cell type of the epidermis). This is the dead skin that you
shed. It makes up 70 -80% of the dust in your house.
Layers of Epidermis
Stratum
Germinativum
(growth layer)
Dermal-Epidermal Junction
• Cements epidermis to dermis
• Polysaccharide gel holds layers together
• Any large detachment can result in severe
infection and death
Dermis
The dermis is the middle layer of the skin.
The dermis is made up two layers
1.
The papillary layer is areolar
connective tissue containing
fine elastic fibers, dermal
papillae and corpuscles of light
touch (Meissner's corpuscles).
2. The reticular layer is irregular
connective tissue containing
collagen and elastic fibers.
–
blood vessels (body temp)
–
lymph vessels
–
hair follicles
–
sebaceous (oil) glands
–
sweat glands(ducts of
sudoriferous)
–
Adipose tissue
Papillary Layer
• Dermal papillae- bumps which
form on superficial layer of the
dermis
• In thick skin papillae line up in
parallel lines which epidermis
binds to, forming finger and
toe prints
• In thin skin papillae are
randomly placed so no ridges
form.
Reticular Layer
• Tough layer of thick
white collagenous
fibers
• Few elastic fibers
• Attachment point of
skeletal and smooth
muscles
• Arrector pili muscles
attach to each hair
follicle, give you goose
bumps
• Sensory receptors are
located in this layer
Growth and Repair of Dermis
• Strength, extensibility, and
elasticity are provided to the
skin by collagen and elastin.
• Lines of cleavage (tension
lines) indicate the direction
of collagen fiber bundles in
the dermis and are
considered in making
surgical incisions.
• Flexure lines- deep
attachment of skin to
muscles. Causes deep
wrinkles.
Langer's cleavage lines
Growth and Repair of Dermis
Scars
– Fibroblasts
reproduce to heal a
wound resulting in
a mass of
connective tissue
Stretch Marks
– If elastic fiber are
stretched too much
or too quickly they
tear
Subcutaneous-superficial fascia-hypodermis
• The subcutis is the
deepest layer and is also
known as the
subcutaneous layer.
• The subcutis, consisting
of a network of collagen
and fat cells, helps
conserve the body's heat
while protecting other
organs from injury by
acting as a "shock
absorber."
Appendages of the Skin
Hair
– Follicles develop
before birth
– Lanugo is hair that
forms before birth
– Vellus hair-strong
fine hair that covers
the body(peach fuzz)
– Terminal Hair- forms
pubic, under arm
hair
– In males terminal
hair replaces vellus
hair on extremities,
chest and beard
Germinal Matrix
– Germinal matrix is highly mitotic and pushes cells up to form hair
– Melanocytes are deposited into hair to give it color
Male Pattern Baldness
Alopecia
• Two conditions need
to me met
– Genes for baldness,
polygenic
– Sex influenced
– Male Hormone
testosterone
Appendages of the Skin
GLANDS
• Sebaceous (oil) glands are
usually connected to hair
follicles, they are absent in
the palms and soles.
– produce sebum, which
moistens hair, waterproofs
and softens skin, and
inhibits bacterial growth.
– Enlarged sebaceous glands
may produce blackheads,
pimples, and boils.
• Ceruminous glands
– modified sebaceous glands
that produce a waxy
substance called cerumen.
They are found in the
external auditory meatus.
Appendages of the Skin
GLANDS
• Sudoriferous (sweat) glandsproduce perspiration,
maintains temperature,
eliminates small amounts of
wastes.
– Eccrine(merocrine)- small
sweat glands found all over,
most abundant, not
associated with hair.
– Apocrine(stinky) limited in
distribution to the skin of
the axilla, pubis, anal, and
areola; ducts open into hair
follicles.
Appendages of the Skin
Nails
• Nails are hard, keratinized epidermal cells over the dorsal
surfaces of the terminal portions of the fingers and toes.
• The principal parts of the nail are the body, free edge, root,
lunula, eponychium, and matrix
• Lunula is latin for “little moon”
The Nail
Eponychium(cuticle)
Nail plate(body)
Thermoregulation
• Body temperature fluctuates very
throughout the day.
• You’re at the highest at days end
and lowest in the morning
• Biochemical reactions and
enzymes function within a
narrow range
• Hypothalamus is the body’s
thermostat
Abnormal Body Temperature
Heat Exhaustion
• Body temperature remains normal
• Loss of large amount of fluids and electrolytes
• Vertigo, nausea and loss of consciousness
Heat Stroke
• Body temp rises above 105 F
• Tacycardia(rapid heart rate)
• Hot dry skin
• Confusion, convulsions
• Body must be cooled immediately or death can result
Hypothermia
• Body temp below 95 F
• Slowed heart rate
• Treated by slowly warming persons body
Frosbite
• Damage results from ice crystals forming in skin
• Necrosis results and if left gangrene can set in
Disorders of the Skin
Albinism
• Every race has about the
same number of
melanocytes
• Skin color is determined by
the amount of melanin
produced(genetic)
• Carotene, yellow pigment
that also contributes to skin
color(fat cells)
• The enzyme tyrosinase is
needed to create melanin
• Sun exposure cause
melanocyte to produce more
melanin
• In albinism tyrosinase is
absent thus they lack
pigment in hair, skin and
eyes
Disorders of the Skin
Epidermolysis bullosa
• Mutation in the keratin
gene.
– Epidermis and dermis is not
held together.
– any friction causes them to
separate and leave open
sores and blister.
– Cases can range from mild
to severe.
– Bone marrow transplants
have proven beneficial.
Disorders of the Skin
Vitiligo
• Charaterized by white patches of skin
• Melanocytes no longer produce pigment
Disorders of the Skin
Onycholysis
• Seperation of nails from the nail bed
• Usually occurs after trauma to nail
Disorders of the Skin
Impetigo
• Caused by staph or strep infections
• Blisters with yellowish or dark scabs
Tinea
• Fungal infections
• Ringworm, athletes foot, thrush, jock
itch
Warts
• Bumpy projections caused by
papilloma viruses
• Easily removed
Boils
• Staph infection of follicles
• Large pus filled lesions
Disorders of the Skin
Acne
• Result of overactive secretion of
sebaceous glands(5-10X more than
normal)
• Pores are clogged and can form infected
pustules
Blisters
• Desmosomes are damaged by injury or
irritation
• Immune response to protect skin
Calluses
• Hardened skin formed by continual
pressure/rubbing
Corns
• Thick hardened skin usually form in bony
areas as a result of friction
Burns
Can be caused by heat, electricity, UV
rays or chemicals
First Degree
• Only the epidermis is damaged,
sunburns normally are first degree
Second Degree
• Epidermis and top layer of dermis are
damaged, blisters form, may have shiny
appearance
Third Degree
• Entire depth of skin destroyed, black or
grayish in color. Skin cannot heal itself,
graphs normally needed
First
Degree
Second Degree
Third Degree
“rule of nines”
• Used to
estimate the
amount of skin
burned
Skin Cancer
most prevalent type of cancer
Non-Malignant
• Basal Cell Carcinoma
• Squamous Cell
Carcinoma
– These two account for
95% of all skin
cancers.
– Rarely metastasize
– Show up on sun
exposed areas
– Lifetime daily
exposure to sun
Malignant(cancerous)
• Melanoma
– can show up
anywhere on the
body
– Metastasizes easily
– Severe burns
increase your risk
Basal Cell Carcinoma
Squamous Cell Carcinoma
Malignant Melanoma
Prevention
• Limit exposure to
sun
• Wear sunscreen
• Screen body
monthly