Download Notes on Integumentary System

Integumentary System
The Skin You’re In
20 square feet
40 lbs shed in your lifetime
8 lbs
The Skin
• It is the largest organ in the body, although it
is easily infected because of its location.
Functions
1. ProtectionOuter most wall of defense
a. Physical barrier: abrasions, dehydration, UV
radiation (aids in production of vitamin D)
b. Biological barrier: microbes (bacterial, fungal,
etc.)
2. Sensationa. Skin acts as a big sensory organ (temp, pain,
pressure)
b. Keeps body informed of changes in
environment
3. Temperature Regulationa. Regulates sweat secretions
b. Regulates blood flow
c. Goose Bumps
PST…
cutaneous membrane
Remember: Membranes must have 2 tissue layers
What are the two layers found in epithelial
membranes?
Epithelium and connective
What are the two layers found in skin?
Epidermis and Dermis
The Structure of Skin
• Epidermis – superficial, thin in some areas of
the body and thicker in others
• Dermis – intermediate, thicker, connective
tissue layer.
• Subcutaneous layer (hypodermis) – deep
tissue layer that attaches skin to underlying
structures.
What type of tissue must that be?
Epidermis
• Its avascular (epithelium)
• Types of cells
– Keratinocyte – cells that produce keratin (protein)
• Most abundant cell in epidermis
• Keratinization – process of filling skin cells with keratin
as they migrate to the surface. The process takes about
2-4 weeks.
– Melanocyte (also found in dermis) – cells that
produce melanin – pigment used to color skin,
eyes and hair.
Epidermis Continued
– Langerhans cells- part of the immune response;
easily damaged by UV rays
– Merkel cell (found in the deepest layer of hairless
skin) – thought to function in sensation of touch.
Epidermis is Composed of Five Sublayers
Deep (inner)
» Startum basale
» Stratum spinosum
» Stratum granulosum
» Stratum lucidium*
» Stratum cornea
Superficial (outer)
Bob’s
Sister
Grace
Loves
Corn
Layers of the Epidermis (from inside out)
• Stratum basale
– Superficial to the
dermis
– Cells undergoing
mitosis
– New cells become
the more
superficial layers
– Dermis and
Stratum Basale
form wavy border
Thin layer
Epidermis Layers
• Stratum spinosum
– 8 to 10 layers
– Production of Keratin begins
• Stratum granulosum
– 2 to 5 layers thick
– Cells are becoming flattened
– Continue to fill with keratin as organelle’s stop
functioning
Thin Skin
Layers of the Epidermis
• Stratum lucidum
– Formed from dead
cells of the deeper
strata
– Prominent in thick,
hairless skin of the
palms of hands and
soles of feet
Epidermis Layers
• Stratum corneum
– 30 layers of dead cells
– Cells are completely full of keratin
– As new cells ascend old cells slough off
In Epidermis Layer
Melanin
• Pigment (melanin) produced by
melanocytes
• Melanocytes are mostly in the
stratum basale
• Amount of melanin produced
depends upon genetics and
exposure to sunlight