1. Skin and Body Membranes
CHAPTER 4
Skin and Body Membranes

2. Function of Body Membranes
Line or cover body surfaces
Protect body surfaces
Lubricate body surfaces

3. Classification of Body Membranes
Epithelial Membranes – are simple organs
Cutaneous membranes
Mucous membrane
Serous membrane
Connective Tissue Membranes

4. Cutaneous Membrane Cutaneous Membrane = skin Superficial Epidermis
A dry membrane because it is exposed to air
Outermost protective boundary
Superficial Epidermis
Keratinized stratified squamous epithelium
Underlying Dermis
Mostly dense connective tissue

5. Mucous Membranes “Wet” or moist membranes Surface Epithelium
Type of epithelium depends on its location
Has a layer of underlying loose connective tissue called the lamina propria
Lines all body cavities that open to the exterior body surface
Respiratory, Digestive, and Reproductive organs
Adapted for absorption or secretion

6. Serous Membranes Serous Membranes = “Serosa”
Surface simple squamous epithelium with underlying areolar connective tissue
Lines open body cavities that are closed to the exterior of the body
Serous membranes occur in pairs:
Parietal = lines the cavity wall
Visceral = covers the outside of the organ contained in the cavity

7. Serous Membranes
Serous layers are separated by serous fluid which helps to reduce friction between organs.
Specific Serous Membranes:
Peritoneum = covers the abdominal cavity
Pleura = surrounds the lungs
Pericardium = surrounds the heart

8. Connective Tissue Membrane
Synovial Membrane
Made of connective tissue only
Lines fibrous capsules surrounding joints

9. Synovial Membrane

10. Integumentary System Components include: Skin = cutaneous membrane
Sweat glands
Oil glands
Hairs
Nails

11. Integumentary System Protects deeper tissues from: Mechanical Damage
Chemical Damage
Bacterial Damage
Thermal Damage
UV Radiation
Drying Out

12. Integumentary System The skin aids in: Heat Regulation
Excretion of urea and uric acid
Synthesizing vitamin D

13. Skin Structure Has 3 layers: Epidermis = outermost layer
Stratified squamous epithelium
Often keratinized (hardened by keratin)
Dermis = middle layer
Dense connective tissue
Firmly connected to epidermis
Hypodermis = aka “subcutaneous” tissue; deep to the dermis
Not part of the skin
Anchors skin to underlying organs
Composed mostly of adipose tissue

14. Skin Structure

15. Layers of the Epidermis
Stratum Basale
Layer lying next to the dermis and is undergoing mitosis
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum
Occurs only in thick skin
Stratum Corneum
20 to 30 cell layers thick
Shingle-like dead cells
Have a totally “new” epidermis every days

16. Melanin Pigment produced by melanocytes
Color is yellow to brown to black
Found mostly in the stratum basale
Amount produced depends upon genetics and the exposure to sunlight

17. Layers of the Dermis Papillary Layer Reticular Layer
Have projections called dermal papillae
Contain pain receptors (Meissner’s corpuscles) and capillary loops
Reticular Layer
Deepest skin layer
Contains blood vessels, glands, and pressure receptors (Pacinian corpuscles)

18. Normal Skin Color Determinants
Melanin = yellow, brown, or black pigments
Carotene = orange-yellow pigment from some vegetables
Hemoglobin = red coloring from blood cells in the dermis capillaries; oxygen content determines the extent of red coloring

19. Accessory Organs of the Skin
Sebaceous Glands = produce oil
Acts as a lubricant for skin and kills bacteria
Most have ducts that empty into hair follicles
Glands are activated at puberty

20. Accessory Organs of the Skin
Sweat Glands = widely distributed in skin
2 types:
Eccrine = open via duct to pore on skin surface
Apocrine = ducts empty into hair follicles
Composition of sweat:
Mostly water, some metabolic waste
Only in apocrine glands – fatty acids & proteins
Function:
Helps get rid of excessive heat
Excretes waste products
Its acidic nature inhibits bacteria growth
Odor is from associated bacteria

21. Accessory Organs of the Skin
Hair – produced by hair follicle
Consists of hard keratinized epithelial cells
Melanocytes provide pigment for hair color

22. Hair
Has a central medulla, a cortex that surrounds it, and a heavily keratinized cuticle on the outside of the cortex

23. Hair
Arrector Pili = muscle that contracts when we are cool to give the appearance of “goose bumps” because it is attached to the hair follicle

24. Accessory Organs of the Skin
Nails = scale-like modifications of the epidermis that are heavily keratinized
Have a lack of pigment that makes them colorless
Stratum basale extends beneath the nail bed so that the nail grows

25. Nails

26. Skin Homeostatic Imbalances
Infections (page 107):
Athlete’s Foot = caused by fungal infection
Boils & Carbuncles = caused by bacterial infection
Cold Sores = caused by a virus
Contact Dermatitis = exposures cause an allergic reaction
Impetigo = caused by bacterial infection
Psoriasis = cause is unknown but is triggered by trauma, infection, and stress

27. Burns (pages 108 – 109)
Tissue damage and cell death caused by heat, electricity, UV radiation, or chemicals
Dangers of burns include dehydration, electrolyte imbalance, and circulatory shock
“Rule of Nines” is a way to determine the extent of burns
Body is divided into 11 areas for quick estimation and each area represents about 9%

28. Severity of Burns 1st Degree Burns = only epidermis is damaged
Skin is red and swollen
2nd Degree Burns = epidermis and upper dermis are damaged
Skin is red with blisters
3rd Degree Burns = destroys entire skin layer
Burn is gray-white or black

29. Burns Burns are considered critical if:
Over 25% of the body has 2nd degree burns
Over 10% of the body has 3rd degree burns
There are 3rd degree burns of the face, hands, or feet

30. Skin Cancer
Skin Cancer = most common type of cancer; abnormal cell mass; 2 types:
Benign – does not spread
Malignant – metastasized (moves) to other parts of the body

31. Basal Cell Carcinoma Least malignant
Most common type arises from stratum basale

32. Squamous Cell Carcinoma
Early removal allows a good chance of cure
Arises from stratum spinosum
Metastasizes to lymph nodes

33. Malignant Melanoma Most deadly of skin cancers Cancer of melanocytes
Metastasizes rapidly to lymph and blood vessels

34. Detection of Skin Cancer
Uses ABCD rule:
A = Asymmetry
2 sides of pigmented mole do not match
B = Border irregularity
Borders of mole are not smooth
C = Color
Different colors in pigmented area
D = Diameter
Spot is larger than 6mm in diameter