3. Functions of the Integumentary
System
1. Protection: from exterior elements
2. Sensation: feeling
3. Excretion of wastes: sweat
4. Synthesis of Vitamin D in sunlight
5. Temperature regulation: release/retain heat
6. Coloration: pigment of skin
7. Water proof: water does not enter inside
8. Growth and repair: regenerate
4. Skin structure 3 main layers
1. Epidermis:outer, thinner layer connected to the
basement membrane
2. Dermis:inner, thicker layer
3. Hypodermis / subcutaneous layer (Sub Q):
Under the dermis (adipose tissue)
5. List & Describe the 4 Cells in
Epidermis
Found on pg. 152 in textbook
5 Minutes to locate & write…GO!
6. Cells of the Epidermis
Keratinocytes – produce the strong protein
keratin.
Melanocytes – produce the brown pigment
melanin
Langerhans’ cells –macrophages that help
activate the immune system response
Merkel cells – function as touch receptors
in association with sensory nerve endings
7. General Epidermis Info
Basement membrane= located right
underneath the stratum basale and
connects epidermis to the dermis
9. Epidermis
outermost layer
Made of keratinized stratified squamous
tissue, so it:
Lacks blood vessels
Is mostly dead
There are 5 distinct layers
MITOSIS does occur in bottom layers
10. 5 layers of the Epidermis
Pg 154 in textbook
12. Stratum spinosum
composed of many
layers of rounded
cells with large nuclei
Langerhans’ cells are
abundant in this layer
13. Stratum granulosum
composed of 3-5 layers of
flattened granular cells
Cells start keratinization
process here the
process of cells formed in
the stratum basale
moving up, flattening,
dying, and becoming hard
and waterproof
14. Stratum lucidum
translucent layer
Not shown in
book…why?
Because only
located in thick skin
of soles and palms
15. Stratum corneum
Top layer
composed of dead
epithelial cells being
flaked off (keratinized)
Functions include:
Waterproofing
Protection from
abrasion and
penetration
16.
17. Dermis
inner layer
Much thicker than the epidermis
Dermis aka. “True Skin”
Contains nerve endings, muscle fibers, hair
follicles, sudoriferous glands, sebaceous glands,
and blood vessels.
Does not continually shed and regenerate itself
18. Dermis: 2 Layers
1. Papillary Layer
Arranged in ridges
The fingertips and toe tips
Ridges allow us to grip things
19. Dermis: 2 Layers…cont’d
2. Reticular Layer
Collagenous fibers: make our skin tough
Elastic fibers: make our skin stretchable.
Reticular fibers: gives skin its strength & resilience
Location of smooth muscle called arrector pili
Stands hair on end when “goose bumps”
20. Subcutaneous layer or hypodermis
adipose tissue and blood vessels
beneath the dermis
Function – insulation
23. Hair
Shaft: visible part of the hair
Medulla: inner core of
the hair
Cuticle: layer covering
medulla
Cortex: Superficial
portion of hair
Root: in dermis
24. No need to know for test…
Just an Interesting FACT:
Straight hair has a rounded follicle
Wavy hair has a flattened follicle
Kinky or curly hair has a kidney shaped follicle
27. Skin Color
3 pigments contribute to skin color
Melanin – yellow to reddish-brown to black
pigment, responsible for skin colors, related to
genetics
• Freckles and pigmented moles – result from local
accumulations of melanin
Carotene – yellow to orange pigment
Hemoglobin – reddish pigment responsible
for the pinkish hue of the skin
28. Pigment
More about Melanin:
Is produced by melanocytes in stratum
basale layer
People of different races have essentially
the same # of melanocytes, but the
amount of melanin produced varies
29. The quantity of Melanin produced
depends on 3 factors:
1. Heredity: MOST IMPORTANT
• enzyme tyrosinase is absent at birth, then
melanocytes are unable to produce melanin and a
condition known as albinism is formed
2. Sunlight Exposure
• Causes melanocytes to increase melanin
production and darkening skin color
3. Hormones: ACTH (Adrenocorticotropic
Hormone ) and MSH (melanin stimulating
hormone)
• Hypersecretion of either hormone may darken the
skin
35. Sudoriferous Glands
Two types
1. Eccrine more common, mainly in forehead,
palms, & soles. These function right at birth. -
no odor in secretion
Secretion = water plus salts and wastes (urea
and uric acid)
2. Apocrine Mainly in armpits, groin, & breasts.
Don’t function until puberty. These cause the
“cold-sweat” during stress. -odor in secretion
36. Sebaceous Glands
-Connected to every hair follicle
-Secrete sebum (oil) into hair follicle
Function – sebum keeps skin and hair soft
Disorders
acne = overproduction of sebum – ducts
clog and inflame