1. Skin and Body Membranes
Chapter 4

2. Body Membranes-Functions
Line or cover body surfaces
Protect body surfaces
Lubricate body surfaces

3. Epithelial Membranes
Made of epithelium connected to underlying connective tissue
Skin
Cutaneous membrane
Exposed to air = Dry membrane
Made of keratinized stratified squamous epithelium

4. Epithelial Membranes, cont.
Mucous membranes
Type of epithelium depends on location of membrane
Most are stratified squamous OR simple columnar
Lines all body cavities open to exterior
Respiratory tract
Digestive tract
Urinary & Reproductive tracts
Wet membranes (bathed in secretions continuously)
Underlying connective tissue is lamina propria

5. Epithelial Membranes, cont.
Serous Membranes
Simple squamous tissue on areolar tissue
Line cavities that are closed to exterior
Occur in pairs
Parietal layer-lines wall of a cavity
Visceral layer-covers the outside of the organs inside the cavity
Layers separated by fluid secreted by both membranes
Allows organs to slide easily across cavity walls and each other
Reduces friction (good for heart pumping, stomach churning, etc)
Peritoneum-lining of abdominal cavity/covers organs
Pleura-surrounds lungs
Pericardium-surrounds heart

6. Epithelial Membranes, cont.

7. Connective Tissue Membranes
Synovial Membranes
Made of areolar tissue-NO epithelial cells
Line joint capsules
Provide smooth surface
Secrete fluid for lubrication (reduces friction)
Also provide cushion for movements of tendons over bones
Tendon sheath

8. Integumentary System AKA…SKIN! AKA…Cutaneous membrane AKA…Integument
Means “covering”
Keeps water and nutrients IN the body
Keeps water and other things OUT
We don’t get waterlogged when we shower or swim!

9. Skin Functions Protects body from: Mechanical damage (bumps)
Physical barrier and pressure receptors
Chemical damage
Impermeable cells; pain receptors
Bacterial damage
Skin secretions acidic; inhibit bacteria
UV radiation
Contains melanin
Thermal damage
Heat/cold damage
Has heat/cold/pain receptors
Dessication
Drying out

10. Skin Functions, cont. Aids in heat loss/retention
Activates sweat glands and allows blood to flush into capillaries for heat loss
Not allowing blood to flush into capillaries for heat retention
Helps excrete urea and uric acid
Sweat glands
Makes vitamin D
Sunlight converts cholesterol in skin to vitamin D

11. Skin Structure Epidermis Outer layer
Keratinized stratified squamous cells
No blood supply of its own (avascular)
Dermis
Dense connective tissue
Can separate from epithelium due to burns/friction
Causes blisters
Hypodermis (Subcutaneous Tissue)
Technically…not part of skin
Adipose (fat)
Anchors skin to underlying organs
Shock absorber
Insulates deeper tissues from extreme temp. changes

12. Epidermis Layers Stratum basale Stratum spinosum Stratum granulosum
Deepest layer
Next to dermis
Cells are undergoing mitosis
AKA Stratum germinativum
Cells get nutrients via diffusion from dermis
Cells get pushed up to move farther away from nutrient supply
Stratum spinosum
Stratum granulosum

13. Epidermis Layers, cont. Stratum lucidum Stratum corneum
Clear, flattened cells full of keratin
Only in areas where skin is hairless and extra thick
Palms of hands
Soles of feet
Stratum corneum
Outermost layer
Shingle-like cells
Dead cells
Provides protective “coat” for body
Rubs/flakes off slowly
We have a totally new epidermis approximately every month!

14. Melanin Pigment produced by melanocytes
In stratum basale
Exposure to sunlight causes melanocytes to make melanin
More melanin = more skin pigmentation = TAN
Amount of melanin produced depends on:
Amount of sun exposure
Genetics
Freckles/Moles
Concentration of melanin in one spot

15. Dermis “Hide” Strong, stretchy, holds body together Two regions
Papillary layer
Contains fingerlike projections “dermal papillae”
Has capillary loops for nutrient supply
Pain/touch receptors
Makes up our fingerprints (whorls, ridges)
Reticular layer
Deepest skin layer
Contains blood vessels, sweat glands, oil glands
Has pressure receptors

16. Skin Structure

17. Skin Color Determination
Amount/kind of melanin in epidermis
Can be yellow, reddish brown, or black
Amount of carotene
Yellowish-orange pigment (think carrots)
If you eat LOTS of foods this color, your skin will look this color also!
Hemoglobin
Protein in red blood cells-carries oxygen
Lots of melanin = brown toned skin
Oxygen rich hemoglobin causes skin to look pink
When Caucasians look “flushed”

18. Imbalances Abnormal yellow skin tone Can be due to liver disorder
Cyanosis
When oxygen content in blood is low
Bluish-tinted skin (“cyan”)
Erythema
Redness/”flushing”
Caused by blood rushing to capillaries near skin’s surface
Pallor/blanching
Pale skin
Can be due to anemia, low BP, impaired blood flow
Jaundice
Abnormal yellow skin tone
Can be due to liver disorder
Bruises
Sites where blood has escaped from circulation and clotted
Tendency toward unusual bruising could mean vit. C deficiency or hemophilia

19. Skin Appendages Cutaneous Glands Exocrine glands
Release secretions to surface of skin through ducts
Two types:
Sebaceous glands
Sweat glands

20. Sebaceous (oil) Glands
All over skin EXCEPT hands/feet
Ducts empty into hair follicle
Release sebum
Oily substance and cell fragments
Lubricant
Keeps skin soft, keeps hair from being brittle
Antibacterial properties
Glands become more active during puberty
Pimples!
Whitehead
Caused by blocked sebaceous gland
Blackheads
When material inside whitehead dries out
Cradle cap (seborrhea)
In infants
Sebaceous glands are overactive
Looks like lots of oily dandruff on scalp

21. Sweat Glands (Sudoriferous Glands)
Eccrine Glands
More numerous/all over body
Open to pores on skin surface
Produce sweat
Important for heat regulation
Apocrine Glands
Only found in axillary and genital areas
Larger than eccrine glands
Ducts empty into hair follicles

22. Sweat Composition Mostly water Waste products
Fatty acids and proteins (from apocrine glands only)
Color
Clear (eccrine)
Milky white/yellowish (apocrine…due to FA’s and proteins)
Function
Heat regulation (gets rid of excess heat)
Waste excretion
Acidic-naturally inhibits bacteria
Odor
Sweat is ODORLESS!!
The smell is from bacteria on skin
When bacteria use sweat for nutrients, it is smelly!

23. Skin Appendages Hair Produced by hair bulb
Made of keratinized epithelial cells (dead…mostly protein)
Color comes from pigment in melanocytes
Found everywhere EXCEPT palms, soles, nipples, lips

24. Hair Anatomy Medulla Central core Cortex Surrounds medulla Cuticle
Outermost layer
Single layer of overlapping cells (like shingles)
Has the most keratin
Provides strength
Split Ends?
Caused when cuticle is worn away at the tip of the hair shaft…keratin frizzes out…hair “splits”

25. Other Hair-Related Structures
Hair Follicle
Inner epidermal sheath= hair
Outer dermal sheath= connective tissue
Supplies blood to epidermis
Arrector pili
Smooth muscle
Connects hair follicle to dermis
When contracted, we see “goose bumps” and hairs are pulled upright
Sebaceous glands

26. Skin Appendages Nails Modification of epidermis Scale-like
Contain lots of keratin
Mostly non-living material
Stratum basale under nail bed resposible for growth
Colorless
No pigment
Appear pink due to blood supply in underlying dermis

27. Burns
Tissue damage/cell death caused by heat, electricity, UV radiation (sunburn/tanning bed), chemicals
Can result in life-threatening problems
Dehydration-lose fluid supply, electrolyte imbalance
Leads to kidney shutdown and circulatory shock
Lost fluids must be replaced immediately!

28. Burns Rule of Nines How to estimate fluid loss from a burn
Divides body into different regions, each being 9% (except genital area is 1%)

29. Burn Classification First-degree Second-degree Third-degree
Only epidermis is damaged
Red, swollen
Regeneration occurs
Ex: sunburn
Second-degree
Damage to epidermis and upper dermis
Red, painful, blisters
Third-degree
Full-thickness burn
Grayish white or black (looks charred)
Destroys nerve endings
Not painful
Regeneration NOT possible
Must use skin grafting

30. Burn Classification

31. Critical Burns Over 25% of body has second-degree burns
Over 10% of body has third-degree burns
There are third-degree burns on face, hands, or feet
Facial burns dangerous
Possible burned airways
Can swell, cause suffocation
Joint injuries
Scar tissue can limit joint mobility

32. Skin Cancer Most common type of cancer Two Types Benign Risk factors:
Overexposure to UV radiation (sun/tanning bed)
Frequent skin infections or chemical irritation
Two Types
Benign
Do not spread
Malignant
Metastasizes (moves) to other parts of body

33. Skin Cancer Basal Cell Carcinoma Squamous Cell Carcinoma
Least malignant
Most common
Occur most often on sun-exposed areas
Slow-growing
99% have full cure if lesion is removed surgically
Squamous Cell Carcinoma
Scaly, red; eventually forms shallow ulcer with raised border
Occurs most often on scalp, ears, hands, lip
Fast-growing
Good chance of cure if removed surgically or use radiation therapy

34. Skin Cancer Malignant Melanoma
Cancer of melanocytes (cells that make melanin)
5% of skin cancers
Often deadly
Can begin anywhere there is pigment
Develops spontaneously, some from moles
50% survival rate
Examine skin for new moles or pigmented spots periodically
Use ABCD Rule of Detection

35. ABCD Rule of Detection (A) Asymmetry Two sides of mole do not match
(B) Border irregularity
Borders of mole/lesion are not smooth
(C) Color
Spot has areas of different colors instead of being one color throughout
(D) Diameter
Spot larger than 6mm (larger than pencil eraser)