Transcript Skin and Body Membranes Chapter 4

Skin and Body Membranes
Chapter 4
2 Types of Body Membranes
A. Epithelial and B. Connective
A. Epithelial Membrane=Skin, Mucous
Membrane, Serous Membrane
B. Connective Membranes=Synovial (areolar
connective tissue) that has no Epithelial cells
Epithelial Membranes
Epithelial Membranes
A. Cutaneous Membrane
"Skin"-Only Dry Membrane
Epidermis
Dermis
Skin
(Integument)
B. Mucous Membrane"Wet"
Lining Exterior Opening
Respitory, Digestive
Urinary, Reproductive
Wet Exterior
Openings
C. Serous Membrane (serosa)
Lining Interior
Occur in pairs like
the "Balloon" example
Interior
Linings
A. Cutaneous/Integument/Skin
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Waterproof-Stretchable-Washable
Self-Repairs: Cuts, Rips, and Burns
Electrical Insulation
Includes: Sweat and Oil Glands, Hairs, and
Nails
Functions of the Skin
Mechanical Damage
Chemical Damage
Bacterial Damage
Ultraviolet Radiation
Thermal Damage
Desiccation
Heat Loss/Retention
Urea and Uric Acid Excretion
Vitamin D
Physical Barrier
Acids and Bases
Unbroken Surface, “Acid Mantle”
Melanin protects from Sun
Heat/Cold/Pain Receptors
Waterproofing Surfaces
Skin Capillary Access
Perspiration
Sunlight
Skin Structure
Epidermis
A. Stratified Squamous
B. Keratinizing (hardening)
Dermis
A. Dense Connective
B. Contains Blood, Sweat,
and Oil Glands
Hypodermis
A. A.K.A Subcuaneous tissue
B. Adipose Tissue
C. Anchor Skin (E&D) to
underlying organs
3 Layers-Actual Picture
Epidermis-5 Strata (Layers)
*****OUTSIDE THE BODY*****
E
P
I
D
E
R
M
I
S
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Corneum
Lucidum
Granulosum
Spinosum
Basale
*****DERMIS*****
Why can we shave (face/legs)
and not bleed?
• The epidermis is AVASCULAR, meaning it has no
blood supply of its own.
• Most cells produce keratin (tough, fibrous protein)
• Basale (alive with spino- and granulo-) absorbs
nutrients, the top 2 (lucid- and corne-) are non-living
Then why do you bleed when
you shave?
Because you cut too deeply and get into the DERMIS
The 5 Strata Layers
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Corneum:20-30 cells thick
Lucidum: dead, clear cells found only on hands/feet
Granulosum: still living cells
Spinosum:living cells
Basale: absorb nutrients from the dermis to
keep them alive, and “float” up to form the
above 4 layers
New EPIdermis every 25-45 days
• Suntans/burns occur in
the Basale
• Melanin (colored
pigment)
• Basale cells
phagocytize (eat) the
melanin
• Melanin shields DNA
from UV rays
The Dermis
• Divided into 2 LayersPapillary and Reticular
Papillary Layer
• Upper projections called papillae containing pain
and touch receptors (known as Meissner’s
corpuscles)
Reticular Layer
• Contains blood
vessels, sweat and oil
glands and deep
pressure receptors
(Pacinian corpusles)
• Many phagocytes to
attack bacteria that has
passed through Epi• Collagen fibers and
blood vessels