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Notes Integumentary System
Section 3 Lecture Outline – Integumentary System
textbook questions Keys
1. Covers and protects the body
What does the skin protect us from?
– Ultraviolet radiation Functions
2. Regulate body temperature
How does it regulate temperature?
– Dilate/constrict of blood vessels
– Goose bumps Functions
3. Excretes Waste
wastes are excreted?
Urea as sweat subcutaneous Functions
4. Reduces water loss
Keeps the body from drying out! Functions
5. Houses sensory receptors Chemo Mechano Chemo Photo Mechano There are 2 main layers of skin
I. Epidermis II. Dermis Epidermis
corneum Outer (surface) layers of skin Dead
lucidum 1030 cells thick Stratum
granulosum Two Parts:
Inner part composed of Stratum
spinosum Lamellar granules Keratinocyte Langerhans cell living cells Outer part is of dead cells Stratum
Sensory neuron Epidermis – Inner layers
Lowest layer of cells reproduce and push older cells toward the surface.
As cells near the surface, they flatten and their organelle disintegrate Epidermis – Inner layers
These cells also begin producing Keratin a tough, fibrous protein.
This replaces cytoplasm. Epidermis – Outer layers
The Keratin producing cells die as they move toward the surface.
Outer dead layer waterproofs and protects inner layers
It is shed continually and is completely replaced in 2 4 weeks Epidermis
What do we find in the epidermis?
What are melanocytes?
Cells that produce melanin.
What is melanin?
A dark brown pigment
What does melanin do?
Gives skin it’s color
Protects sensitive dermis from UV radiation Epidermis
Do some people have
than other people? Epidermis
Skin pigmentation is due to the type and amount of melanin produced
Eumelanin produces darker pigments
Phaeomelanin produces lighter pigments and freckles
These often occur together in varying amounts Melanocyte Dermis
Deeper layers of skin
1020 times thicker
Top layer arranged
Why are there
Ridges help the epidermis bind to the dermis.
The uneven ridges
create fingerprints Dermis Accessory Organs of the Dermis
1. Hair follicles – tubelike depression where the hair develops Accessory Organs of the Dermis
2. Sebaceous glands – secret oily sebum to soften and waterproof skin Accessory Organs of the Dermis
3. Nails – protective covers of ends of fingers and toes. Accessory Organs of the Dermis
4. Sweat glands: – secrete waste
– regulate heat
– produces ear wax
– produces milk during lactation Accessory Organs of the Dermis
5. Blood vessels – to nourish skin cells Accessory Organs of the Dermis
6. Nerves – to send and receive messages Subcutaneous Accessory Organs of the Dermis
7. Erector pilli muscle
causes hair to stand erect subcutaneous Subcutaneous layer – connective
Anchors dermis to the body
cells to protect
Subcutaneous layer Self Quiz
L. M. A. K. B. J. C. I. H. G. F. E. D. I. Blood vessels
H. Connective tissue
G. Fat cells
J. Hair follicle
K. Sebaceous gland
C. Subcutaneous layer
E. Sweat pore
M. Disorders of the Skin
Acne – infection of sebaceous gland Disorders of the Skin
Benign tumor – fleshy growths on neck, armpits and body. Harmless! Tumor Disorders of the Skin
Vascular Birthmarks – Blood vessel abnormality affecting .5% of population – darkens skin Disorders of the Skin
Dermatitis – dry, sensitive skin Disorders of the Skin
Nail Fungus Disorders of the Skin
Fungal infections Athlete’s Foot Ring Worm Disorders of the Skin
Impetigo – bacterial infection Disorders of the Skin
Psoriasis – chronic inflammation Disorders of the Skin
Carcinoma Melanoma Disorders of the Skin
Warts viral infection Common wart Plane warts Plantar wart Disorders of
Second degree Third degree Interesting Tidbits
Your body is composed of approximately 100 Trillion cells
About 16% of your body weight is skin
The skin is completely renewed every 27 days
You will make almost 1000 new skins in a lifetime
If all the layers of your skin were laid out on the ground, it would cover about 20 m2 or 2 parking spaces Interesting Tidbits
A fingernail or toenail takes about 6 months to grow from base to tip
Fingernails grow faster than toenails
An average human scalp has 100,000 hairs
We lose between 40 and 100 hairs per day
Blondes have more hair than brunettes Interesting Tidbits
Fingerprints provide traction for grasping objects
Even identical twins have different fingerprints
Every square inch of dermis contains twenty feet of blood vessels
Skin on our hands and feet is thicker. When we bathe, skin takes on water and swells slightly.
In the thicker areas, increased surface area creates crowding. The skin must wrinkle to accommodate the changes Interesting Tidbits
Friction of the epidermis causes cell division to increase.
This outward thickening is called a callous.
Sometimes growth is inward, creating a corn.
Humans shed about 600,000 particles of skin per hour – about 1.5 pounds per year.
At age 70, you will have lost about 105 lbs of skin. ...
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- Winter '11