1. Bram Welch-Horan (tbw5)
SSN Session
Skin
Jennifer Chang (jtc2109)
Bram Welch-Horan (tbw5)
October 19, 2005

2. Functions Protection - barrier to outside environment
abrasion, moisture, UV light, microorganisms
Homeostasis - maintenance of internal environment
temperature, water and salts
Sensation
touch, temperature, pain, pressure, vibration
Immune surveillance
Langerhans’ cells – type of macrophage
Endocrine function
synthesizes vitamin D

3. Types of Skin
Thick – covers palms of hands and soles of feet, glabrous
vs.
Thin – covers rest of body, mostly hairy
Hairy
Glabrous

4. 3 layers Epidermis stratified squamous keratinizing epithelium Dermis
papillary layer of loose connective tissue underlain by dense irregularly arranged CT
Hypodermis
aka subcutaneous tissue, loose CT, contains adipose tissue
Subcutaneous layer corresponds to the superficial fascia

5. Epidermis – stratified squamous keratinized epithelium
5 Layers
1. Stratum corneum
2. Stratum lucidum
3. Stratum granulosum
4. Stratum spinosum
5. Stratum basalis

6. Stratum corneum Stratum granulosum Superficial keratinized layer
Cells have no nuclei or organelles
Sealed extracellular space
Most superficial cells are sloughed off
Stratum granulosum
Basophilic granules of keratohyalin
Promotes aggregation of keratin filaments into tonofibrils
Lamellar bodies – water barrier
Stratum corneum

7. Stratum Spinosum several cell layers thick
desmosomes
several cell layers thick
attached by intercellular bridges (desmosomes)
cells artificially pulled apart, the attachment sites give spiny appearance
Langerhans’ cells found here

8. Stratum Basalis mitotic cell cells with melanin
Mitotic cell layer, attaches to basement membrane via hemidesmosomes
Cells containing melanin may be either melanocytes or keratinocytes
Melanin
- pigment - protection from UV rays
- synthesized in melanocytes using tyrosinase - taken up by keratinocytes

9. Question 1
In the stratum basalis, ______ are found. They attach keratinocytes to ______.
Hemidesmosomes, basal lamina
Desmosomes, basal lamina
Hemidesmosomes, other keratinocytes
Desmosomes, Langerhans cells
Lab 8, slide 2

10. Question 1
In the stratum basalis, ______ are found. They attach keratinocytes to ______.
Hemidesmosomes, basal lamina
Desmosomes, basal lamina
Hemidesmosomes, other keratinocytes
Desmosomes, Langerhans cells
Lab 8, slide 2

11. Question 2 Which of the following regarding these cells is true?
They are mitotic
They do not have organelles
They contain keratohyalin granules
They synthesize melanin

12. Question 2 Which of the following regarding these cells is true?
They are mitotic
They do not have organelles
They contain keratohyalin granules
They synthesize melanin

13. Question 3 This brown substance is synthesized in which cell layer?
Stratum corneum
Stratum granulosum
Stratum spinosum
Stratum basalis

14. Question 3 This brown substance is synthesized in which cell layer?
Stratum corneum
Stratum granulosum
Stratum spinosum
Stratum basalis

15. Specialized Structures in Skin
Nerve supply
Hair follicles
Sweat glands
Sebaceous glands
(Nails)
(Mammary glands) (

16. The Dermis Papillary layer Reticular layer loose CT
bv’s, nerves, lymphatics
papillae into epidermis
Meissner’s corpuscles
Reticular layer
dense CT (less cellular)
eccrine sweat glands
Pacinian corpuscles
anatomy: Langer’s lines
(Ross, 4/e, p. 425)

17. Cutaneous Nerve Endings
(Free nerve endings)
pain & temperature
(Merkel’s cells)
high-res. tactile sensation
(in stratum basale)
Meissner’s Corpuscles
touch
Pacinian Corpuscles
vibration & pressure
(Skin lab, slide 16; Cajal stain)

18. Meissner’s Corpuscles
in dermal papillae (papillary layer of dermis)
mechanoreceptors
2-point discrimination
encapsulated
CT capsule
contrast w/ free nerve endings
(Ross, 4/e, p. 412)

19. Pacinian Corpuscles
(Ross, 4/e, p. 431)

20. Pacinian Corpuscles in deeper dermis & hypodermis vibration & pressure
reticular layer
vibration & pressure
encapsulated
characteristic appearance
“onion” / “bull’s eye”
diagnostic for dermis
or hypodermis
hypodermis
loose CT, bv’s, fat, etc.
a.k.a., subcutaneous tissue, superficial fascia
(Skin lab, slide 18)

21. Hair Follicles epithelially derived most of body surface
epidermal invagination
matrix of follicle equiv. to stratum basale
most of body surface
body temp. regulation
sebaceous glands
secrete into follicle
arrector pili
smooth muscle
“goosebumps”
assists gland secretion
(Ross, 4/e, p. 414)

22. Sebaceous Glands associated w/ hair follicle
secrete sebum between shaft & follicle
holocrine secretion
oil-filled cells apoptose
secretory product & cell debris discharged from gland
sebum may be protective
but is involved in acne
(Skin lab, slide 21)

23. Eccrine Sweat Glands coiled tubular glands in dermis (reticular layer)
not associated with hair follicles; widely distributed
secretory portion (w/ basal lamina)
myoepithelial cells
contract  expel sweat
ducts – cuboidal cells
stratified (2 layers)
corkscrew path
reabsorb H2O, salt
sweat is hypotonic
contains H2O, salt, IgA
temp. regulation
(Skin lab, slide 13)

24. Sweat Ducts
(Skin lab, slide 12)

25. Question 4
What is the function of this nerve ending, and which skin layer is it in?
a) pain; hypodermis
b) temp.; reticular layer
c) two-pt. discrimination; papillary layer
d) itch; epidermis
(Skin lab, slide 15)

26. Question 4
What is the function of this nerve ending, and which skin layer is it in?
a) pain; hypodermis
b) temp.; reticular layer
c) two-pt. discrimination; papillary layer
d) itch; epidermis
(Skin lab, slide 15)

27. Question 5
The product of the gland in this image would most likely be:
a) attractive to a potential mate
b) hypotonic
c) mainly water
d) oily and associated with cell debris
(Skin lab, slide 23)

28. Question 5
The product of the gland in this image would most likely be:
a) attractive to a potential mate
b) hypotonic
c) mainly water
d) oily and associated with cell debris
(Skin lab, slide 23)