1. Integumentary System

2. Functions Covers and protects the body
What does the skin protect us from?
Pathogens
Injury
Ultra-violet radiation

3. Functions How does it regulate temperature?
2. Regulate body temperature
How does it regulate temperature?
Sweating
Dilate/constrict of blood vessels
Goose bumps

4. Functions 3. Excretes Waste What wastes are excreted? Urea as sweat
subcutaneous

5. Functions
4. Reduces water loss Keeps the body from drying out!

6. Functions 5. Houses sensory receptors Chemo Mechano Chemo Photo

7. Four basic types of integumentary tissue
Epithelium – epidermis
Connective tissue - dermis
Muscle tissue
Nervous tissue

8. There are 2 main layers of skin
I. Epidermis
II. Dermis

9. Epidermis Keratinized stratified squamous epithelium
Four types of cells
Keratinocytes – deepest, produce keratin (tough fibrous protein)
Melanocytes - make dark skin pigment melanin
Merkel cells – associated with sensory nerve endings
Langerhans cells – macrophage-like dendritic cells
Layers (from deep to superficial)
Stratum basale or germinativum – single row of cells attached to dermis; youngest cells
Stratum spinosum – spinyness is artifactual; tonofilaments (bundles of protein) resist tension
Stratum granulosum – layers of flattened keratinocytes producing keratin (hair and nails made of it also)
Stratum lucidum (only on palms and soles)
Stratum corneum – horny layer (cells dead, many layers thick)
(see figure on next slide)

10. Epidermis Outer (surface) layers of skin Two Parts:
Dead
keratinocytes
Lamellar granules
Keratinocyte
Langerhans cell
Melanocyte
Merkel cell
Tactile disc
Sensory neuron
Stratum
corneum
lucidum
granulosum
spinosum
basale
Dermis
Outer (surface) layers of skin
10-30 cells thick
Two Parts:
Inner part composed of living cells
Outer part is of dead cells

11. Epidermis Inner layers
Lowest layer of cells reproduce and push older cells toward the surface.
As cells near the surface, they flatten and their organelle disintegrate

12. Epidermis Inner layers
These cells also begin producing Keratin a tough, fibrous protein.
This replaces cytoplasm.

13. Epidermis – Outer layers
The Keratin producing cells die as they move toward the surface.
Outer dead layer waterproofs and protects inner layers
It is shed continually and is completely replaced in weeks

14. Epidermis
What do we find in the epidermis? Melanocytes What are melanocytes? Cells that produce melanin. What is melanin? A dark brown pigment What does melanin do? Gives skin it’s color Protects sensitive dermis from U-V radiation

15. Skin color Three skin pigments
Melanin: the most important
Carotene: from carrots and yellow vegies
Hemoglobin: the pink of light skin
Melanin in granules passes from melanocytes (same number in all races) to keratinocytes in stratum basale
Digested by lysosomes
Variations in color
Protection from UV light vs vitamin D?

16. Epidermis NO! Melanocytes Do some people have more melanocytes
than other people?
NO!

17. Epidermis
Skin pigmentation is due to the type and amount of melanin produced
Eumelanin produces darker pigments
Phaeomelanin produces lighter pigments and freckles
These often occur together in varying amounts

18. Dermis
Deeper layers of skin times thicker than epidermis. Top layer arranged In ridges.

20. Dermis Ridges help the epidermis bind to the dermis. The uneven ridges
create fingerprints

21. Accessory Organs of the Dermis
1. Hair follicles – tube-like depression where the hair develops

22. Hair and hair follicles: complex Derived from epidermis and dermis Everywhere but palms, soles, nipples, parts of genitalia
*“arrector pili” is smooth muscle *
Hair bulb: epithelial cells surrounding papilla
Hair papilla
is connective tissue________________

23. Make up of hair – hard keratin Three concentric layers
Functions of hair
Warmth – less in man than other mammals
Sense light touch of the skin
Protection - scalp
Parts
Root imbedded in skin
Shaft projecting above skin surface
Make up of hair – hard keratin
Three concentric layers
Medulla (core)
Cortex (surrounds medulla)
Cuticle (single layers, overlapping)

24. Hair growth: averages 2 mm/week
Types of hair
Vellus: fine, short hairs
Intermediate hairs
Terminal: longer, courser hair
Hair growth: averages 2 mm/week
Active: growing
Resting phase then shed
Hair loss
Thinning – age related
Male pattern baldness
Hair color
Amount of melanin for black or brown; distinct form of melanin for red
White: decreased melanin and air bubbles in the medulla
Genetically determined though influenced by hormones and environment

25. Accessory Organs of the Dermis
2. Sebaceous glands – secret oily sebum to soften and waterproof skin

26. Sebaceous (oil) glands
Entire body except palms and soles
Produce sebum by holocrine secretion
Oils and lubricates

27. Accessory Organs of the Dermis
3. Nails – protective covers of ends of fingers and toes.

28. Nails Of hard keratin Corresponds to hooves and claws
Grows from nail matrix

29. Accessory Organs of the Dermis
4. Sweat glands:
secrete waste
regulate heat
produces ear wax
produces milk during lactation

30. Sweat glands
Entire skin surface except nipples and part of external genitalia
Prevent overheating
500 cc to 12 l/day! (is mostly water)
Humans most efficient (only mammals have)
Produced in response to stress as well as heat

31. Types of sweat glands Eccrine or merocrine Apocrine
Most numerous
True sweat: 99% water, some salts, traces of waste
Open through pores
Apocrine
Axillary, anal and genital areas only
Ducts open into hair follices
The organic molecules in it decompose with time - odor
Modified apocrine glands
Ceruminous – secrete earwax
Mammary – secrete milk

33. Types of sweat glands Eccrine or merocrine Apocrine
Most numerous
True sweat: 99% water, some salts, traces of waste
Open through pores
Apocrine
Axillary, anal and genital areas only
Ducts open into hair follices
The organic molecules in it decompose with time - odor
Modified apocrine glands
Ceruminous – secrete earwax
Mammary – secrete milk

34. Accessory Organs of the Dermis
5. Blood vessels – to nourish skin cells

35. Accessory Organs of the Dermis
6. Nerves – to send and receive messages
Subcutaneous

36. Accessory Organs of the Dermis
7. Erector pilli muscle -smooth muscle -causes “goosebumps” hair to stand erect
subcutaneous

37. Subcutaneous layer – connective tissue
Anchors dermis to the body Contains fat cells to protect and cushion
Subcutaneous layer

38. Some disorders of the integumentary system
Burns
Threat to life
Catastrophic loss of body fluids
Dehydration and fatal circulatory shock
Infection
Types
First degree – epidermis: redness (e.g. sunburn)
Second degree – epidermis and upper dermis: blister
Third degree - full thickness
Infections
Skin cancer

39. Disorders of the integumentary system
Burns
Threat to life
Catastrophic loss of body fluids
Dehydration and fatal circulatory shock
Infection
Types
First degree – epidermis: redness (e.g. sunburn)
Second degree – epidermis and upper dermis: blister
Third degree - full thickness
Infections
Skin cancer

40. Interesting Tidbits
Your body is composed of approximately 100 Trillion cells
About 16% of your body weight is skin
The skin is completely renewed every 27 days
You will make almost 1000 new skins in a lifetime
If all the layers of your skin were laid out on the ground, it would cover about 20 m2 or 2 parking spaces

41. Interesting Tidbits
A fingernail or toenail takes about 6 months to grow from base to tip
Fingernails grow faster than toenails
An average human scalp has 100,000 hairs
We lose between 40 and 100 hairs per day
Blondes have more hair than brunettes

42. Interesting Tidbits Fingerprints provide traction for grasping objects
Even identical twins have different fingerprints
Every square inch of dermis contains twenty feet of blood vessels
Skin on our hands and feet is thicker. When we bathe, skin takes on water and swells slightly.
In the thicker areas, increased surface area creates crowding. The skin must wrinkle to accommodate the changes

43. Interesting Tidbits
Friction of the epidermis causes cell division to increase.
This outward thickening is called a callous.
Sometimes growth is inward, creating a corn.
Humans shed about 600,000 particles of skin per hour – about 1.5 pounds per year.
At age 70, you will have lost about 105 lbs of skin.