1. The Integument

2. Overview of the Integumentary System

3. Organization of the Epidermis:
Figure 5–2

4. Layers of the epidermis are known as “strata”

5. Layers of the Epidermis
Top: Free surface of skin
- stratum corneum
- stratum lucidum
- stratum granulosum
- stratum spinosum
stratum germinativum
Bottom: Basal lamina

6. A note on thick vs. thin skin
Thick skin has an extra layer (lucidum) but that is NOT the reason that it is thicker than thin skin.
Real reason is the other layers are thicker in thick skin than in thin skin.

7. The Dermis Deeper part of cutaneous layer
Located between epidermis and subcutaneous layer
Anchors epidermal accessory structures (hair follicles, sweat glands)
Has 2 components:
outer papillary layer
deep reticular layer

8. The Papillary Layer Consists of areolar tissue
Contains smaller capillaries, lymphatic vessels, and sensory neurons
Has dermal papillae projecting between epidermal ridges

9. The Reticular Layer Consists of dense irregular connective tissue
Contains larger blood vessels, lymph vessels, and nerve fibers
Contains collagen and elastic fibers

10. Integumentary Accessory Structures
Hair, hair follicles, sebaceous (oil) glands, sweat glands, and nails:
are derived from embryonic epidermis
are located in dermis
project through the skin surface

11. The Hair Follicle Is located deep in dermis
Is made of epidermal tissue (with connective tissue around the outside)
Produces nonliving hairs
Is wrapped in a dense connective-tissue sheath
Base is surrounded by sensory nerves

12. Hair

13. Structures of Hair and Follicles
Figure 5–9a

14. Accessory Structures of Hair
Arrector pili:
involuntary smooth muscle
causes hairs to stand up
produces “goose bumps”
Sebaceous glands:
lubricate the hair
control bacteria

15. Inside the Follicle
Figure 5–9b

16. Exocrine Glands in the skin
Sebaceous glands and follicles (oil glands):
holocrine glands
secrete sebum
Sweat glands:
merocrine glands
watery secretions

17. Types of Sebaceous Glands
associated with most hair follicles (on head and body)
Sebaceous follicles:
discharge directly onto skin surface
found on face and trunk
when clogged  acne

18. Sebaceous glands

19. Types of Sweat Glands Apocrine: Merocrine:
found in armpits, around nipples, and groin
Merocrine:
more numerous, widely distributed on body surface
especially on palms and soles (thick skin)
 Both are actually merocrine

20. “Apocrine” Sweat Glands
Merocrine secretions, not apocrine
Associated with hair follicles in groin, nipples, and axillae (armpits)
Become active at puberty
Produce sticky, cloudy secretions (thick sweat) that breaks down and causes odor

21. Merocrine Sweat Glands
Also called eccrine glands:
coiled, tubular glands
discharge directly onto skin surface
sensible perspiration for cooling (thin sweat)
water, salts, and organic compounds

22. Sweat Glands of the Skin
Merocrine
Apocrine

23. Epidermis What to look for:
Usually darkest between stratum germinativum and stratum granulosm (granulosm often a dark meandering line)
Keratinized cells (s. corneum) often lift off the underlying layers
S. germinativum along basal lamina, along with melanocytes

24. Dermis: Papillary vs. Reticular layer

25. What to look for Papillary layer Reticular layer Hypodermis has ridges
is areolar
Just under basal lamina
Reticular layer
much thicker
Dense irregular CT
Hypodermis
Loose CTP

26. More skin

27. Merocrine sweat gland What to look for Found in most skin
Coiled, tubular
Small lumens in cross section
Have duct that goes all the way to the epidermal surface and ends in sweat pore
Smaller than apocrine, don’t extend as deep into dermis

28. Apocrine sweat gland What to look for: Associated with hair follicle
Only in nipples, groin, armpit
Large lumens
Deeper in dermis than merocrine

29. Apocrine sweat gland

30. Hair with sebaceous glands and arrector pilli

31. Hair What to look for: Follicles are rarely complete
Can often see root, papilla at base of hair
Arrector pilli muscle at an angle
Associated glands (which are?)

32. Sebaceous glands

33. Sebaceous glands What to look for: Associated with hair follicle
Found most everywhere hair follicles are found in skin
Look like cauliflower (maybe?)

34. Sebaceous follicle

35. Sebaceous follicle What to look for: Also look like cauliflower
Found on face and trunk only
NOT associated with hair follicle
Have duct that opens onto skin surface

36. Lab Activity #7 Look at slides: Axillary skin (armpit)
Pigmented and Nonpigmented thin skin slide
Scalp

37. What will you find there?
Armpit Scalp
Hair?
Hair follicle?
Sebaceous gland?
Sebaceous follicle?
Apocrine sweat gland?
Merocrine sweat gland? Y Y Y Y Y Y ? N Y N Y Y