Welcome to Day 29
Question of the Day 1
 List
the main structures that make
up the integumentary system
 List 3 functions of the Integumentary
system
Integumentary System

Composed mostly of the skin

Other accessory structures include:
 Hair
 Nails
 glandsnds
Functions

Maintenance of body temperature

Protection

Perception of stimuli

Excretion/secretion

Synthesis of vitamin D

Non-specific immunity
Main layers of the skin

http://bcove.me/uc4541e9
 Epidermis
- Superficial
 Dermis
 Hypodermis
– Deep
Subcutaneous
layer
Epidermis

Keratinized stratified squamous
 Most

superficial layer of the skin
Cells of Epidermis
 Majority
are keratinocytes –
produce keratin; waterproofs
skin
 Melanocytes
– make melanin –
color pigment; absorbs UV light
 Langerhans’
cells – macrophages
that activate immune systeml
cells – associate with sensory
nerve endings
Layers of Epidermis
 Stratum
Basale – Deepest layer
 Site
of mitosis; new cells are
produced here!
 Single
row of cuboidal or columnar
keratinocytes
 Attached
to basement membrane
Separates
epidermis from dermis
 Keratinocytes,
cells
melanocytes, Merkel
Stratum Spinosum
 Above
the Stratum Basale
 8-10 layers of keratinocytes
 Some cells can still divide
 Provides strength and flexibility
 Langerhans’ cells here
Stratum Granulosum
 Superficial
to the Stratum
Spinosum
 3-5
layers of keratinocytes
 First
layer of keratinization
 Keratinocytes
fill with keratin
 Nucleus
and organelles
disintegrate
 Fully
keratinized cell is dead but
structurally sound
Stratum Lucidum
Superficial to Stratum
Granulosum
2-3 layers of keratinocytes
Found only in thick skin
Palms
of hands soles of feet
Stratum Corneum
Superficial
to Stratum
Granulosum or stratum
Lucidum
20-30
layers of dead
interlocking keratinized cells
No
Most
nucleus or organelles
superficial layer
Secretions
prevent growth of
microorganisms
Migration of Keratinocytes
Originate
from stem cells in
stratum basale
Migrate through strata over
2 weeks and change in
structure
Remain in stratum corneum
for another 2 weeks
Then cells are shed
Thick vs. Thin skin
 Thick
skin
 Palms of hands,
soles of feet
 All 5 layers of strata
 Sweat glands- yes
 hair follicles- no
 0.4-0.6mm thick
•Thin skin
•Covers the rest of body
•No stratum lucidum
•Sweat glands- yes
•Hair follicles-yes
•0.075-0.150 mm thick
Epidermis foldable

Create a foldable to illustrate the structures and functions of the
layers of the epidermis

Front – Label top: Superficial, Label bottom: Deep

Cut layers like flaps, list names of each layer

Inside each flap – describe number of layers of cells, function of
layer, and other important characteristics

On right side inside – sketch a picture of the layer

On back describe the steps of keratinization and movement of
cells from basal layer to the superficial layer

Use COLOR!!
Before you go today… Exit Ticket Please!
Describe
the main parts of the integumentary
system
Describe the functions of the Integumentary
System
Describe the main layers of the skin
Describe the layers of the Epidermis –
structure and function
Stratum corneum
Most superficial layer; 20–30 layers of dead
cells represented only by flat membranous
sacs filled with keratin. Glycolipids in
extracellular space.
Stratum granulosum
Three to five layers of flattened cells,
organelles deteriorating; cytoplasm full of
lamellated granules (release lipids) and
keratohyaline granules.
Stratum spinosum
Several layers of keratinocytes unified by
desmosomes. Cells contain thick bundles of
intermediate filaments made of pre-keratin.
Stratum basale
Deepest epidermal layer; one row of actively
mitotic stem cells; some newly formed cells
become part of the more superficial layers. See
occasional melanocytes and epidermal
dendritic cells.
Desmosomes
Melanin granule
Melanocyte
(b)
Keratinocytes
Dermis
Sensory
nerve ending Epidermal
Tactile
dendritic cell
(Merkel) cell
Figure 5.2b