1. Ch. 4 Skin and Body Membranes

2. Epithelial Membranes Cutaneous membrane (skin)
(a) Cutaneous membrane (the skin) covers the body surface.
Figure 4.1a

3. Epithelial Membranes Mucous membranes (mucosa)
Line body cavities that open to exterior (e.g., digestive and respiratory tracts)
Mucosa of
nasal cavity
Mucosa of
mouth
Esophagus
lining
Mucosa of
lung bronchi
Figure 4.1b

4. Epithelial Membranes Serous Membranes
Paired membranes that line closed ventral body cavities
Parietal layer –lines body walls
Visceral layer- covers internal organs
Serous Membranes are named based on their location:
Pleural membranes surround: lungs
Pericardial membranes surround: heart
Peritoneal membranes surround: viscera

5. Epithelial Membranes Parietal peritoneum Parietal pleura Visceral
pericardium
Visceral
pericardium
Figure 4.1c

6. Skin (Integument) Consists of three major regions
Epidermis—superficial region
Dermis—middle region
Hypodermis —deepest region
Mostly adipose tissue

7. Epidermis
Papillary
layer
Dermis
Reticular
layer
Hypodermis

8. Epidermis Keratinized stratified squamous E.T. Cells of epidermis
Keratinocytes—produce fibrous protein keratin
Melanocytes
Produce brown pigment melanin

9. Layers of the Epidermis: Stratum Basale
Deepest epidermal layer firmly attached to dermis
One cell layer
Mitotic cells that travel from basal layer to surface
Takes 25–45 days
Contains melanocytes

10. Layers of the Epidermis: Stratum Spinosum
~5-6 cell layers
Living, flatter cells
Mostly filled with keratin

11. Layers of the Epidermis: Stratum Granulosum
2-3 cell layers
Living cells
Mostly filled with keratin

12. Layers of the Epidermis: Stratum Lucidum
A few rows of flat, dead keratinocytes
Thin, transparent band superficial to the stratum granulosum
Only in soles and palms

13. Layers of the Epidermis: Stratum Corneum
20–30 rows of dead, flat, keratinized cells
3/4 of the epidermal thickness
Protects from abrasion and penetration & waterproofs the skin

14. Keratinocytes Stratum corneum Stratum granulosum Stratum spinosum
Stratum basale
Dermis
Sensory
nerve ending
Melanin granule
Epidermal
dendritic cell
Melanocyte
Tactile
(Merkel) cell
(b)
Figure 5.2b

15. Dermis Made up of Two layers: Papillary Layer Reticular Layer
Composed of areolar C.T.
Reticular Layer
Composed of dense irregular C.T.

16. Epidermis
Papillary
layer
Dermis
Reticular
layer
Hypodermis

17. Layers of the Dermis: Papillary Layer
Contains dermal papillae which may have:
Capillary loops
Meissner’s Corpuscles
Free nerve endings

18. Hair shaft
Dermal papillae
Epidermis
Subpapillary
vascular plexus
Papillary
layer
Pore
Appendages
of skin
Dermis
Reticular
layer
• Eccrine sweat
gland
• Arrector pili
muscle
Hypodermis
(superficial fascia)
• Sebaceous
(oil) gland
• Hair follicle
Nervous structures
• Hair root
• Sensory nerve fiber
Cutaneous vascular
plexus
• Pacinian corpuscle
• Hair follicle receptor
(root hair plexus)
Adipose tissue

19. Layers of the Dermis: Reticular Layer
Most glands, hair follicles, emerge from the dermis

20. Skin Color Three pigments contribute to skin color: Melanin Carotene
Yellow to reddish-brown to black, responsible for dark skin colors
Carotene
Yellow to orange, most obvious in the palms and soles
Hemoglobin
Responsible for the pinkish hue of skin

21. Appendages of the Skin Appendages are derived from the epidermis
Sweat glands
Oil glands
Hairs and hair follicles
Nails

22. Sweat Glands Two main types of sweat glands
Eccrine sweat glands—abundant on palms, soles, and forehead
Sweat: 99% water, NaCl, vitamin C, antibodies, metabolic wastes
Ducts connect to pores
Thermoregulatory function

23. Sweat pore
Eccrine
gland
Sebaceous
gland
Duct
Dermal connective
tissue
Secretory cells

24. Sweat Glands
Apocrine sweat glands—confined to axillary and anogenital areas
Sebum: sweat + fatty substances and proteins
Ducts connect to hair follicles
Functional from puberty onward

25. Sebaceous (Oil) Glands
Most develop from hair follicles
Secrete Sebum:
Oily secretion
Bactericidal
Softens hair and skin

26. Sweat pore Sebaceous gland Dermal connective tissue Eccrine Sebaceous
gland duct
Eccrine
gland
Hair in
hair follicle
Secretory cells
Figure 4.6

27. Hair Functions Alerts the body to presence of objects on the skin
Guards the scalp against physical trauma, heat loss, and sunlight
Consists of three layers of squamous keratinocytes: cuticle (outermost layer), cortex, medulla
Surrounded by a hair follicle

28. Follicle wall
Hair shaft
Hair
• Cuticle
• Cortex
• Medulla
Arrector
pili
Sebaceous
gland
Hair root
Hair bulb

29. Hair Follicle Two layered wall consisting of CT and ET
Hair bulb: expanded deep end
Hair follicle receptor (root hair plexus):
Sensory nerve endings around each hair bulb

30. Hair Follicle Arrector pili Smooth muscle attached to follicle
Contraction of these muscles causes the hairs to stand on end (forming “goose bumps”)

31. Subcutaneous adipose tissue (c)
Hair shaft
Arrector
pili
Sebaceous
gland
Hair root
Follicle wall
Hair bulb
Hair root
• Cuticle
• Cortex
• Medulla
Hair matrix
Hair papilla
Melanocyte
Subcutaneous adipose tissue
(c)
Figure 4.7

32. Structure of a Nail Scalelike modification of the epidermis
Structures of the nail: Free edge, body, nail matrix, nail bed, hyponichium, eponichium,

33. Lateral
nail fold
Lunule
(a)
Free edge
of nail
Body
of nail
Eponychium
(cuticle)
Proximal
nail fold
Nail bed
Root of nail
Nail
matrix
(b)
Hyponychium
Phalanx (bone of fingertip)

34. Functions of the Integumentary System
Protection
Chemical
Low pH secretions retard bacterial activity
Physical/mechanical barriers
Keratin and glycolipids block most water and water- soluble substances
Biological barriers
Macrophages

35. Functions of the Integumentary System
Body temperature regulation
At elevated temperature, dilation of dermal vessels and increased sweat gland activity cool the body
Cutaneous sensations
Temperature, touch, and pain

36. Functions of the Integumentary System
Metabolic functions
Synthesis of vitamin D precursor
Blood reservoir—up to 5% of body’s blood volume
Excretion—nitrogenous wastes and salt in sweat

37. Basal Cell Carcinoma Least malignant, most common
Appearance: Red, shiny, raised nodule
Stratum basale cells proliferate and slowly invade dermis and hypodermis
Cured by surgical excision in 99% of cases

38. Squamous Cell Carcinoma
Second most common
Appearance: flat and scaly
Involves keratinocytes of stratum spinosum
Good prognosis if treated by radiation therapy or removed surgically

39. Melanoma Most dangerous type
Appearance: black/brown spreading patch; may develop from pre-existing moles
Highly metastatic and resistant to chemotherapy; most dangerous
Treated by wide surgical excision accompanied by immunotherapy

40. Melanoma Characteristics (ABCD rule)
A: Asymmetry; the two sides of the pigmented area do not match
B: Border exhibits indentations
C: Color is black, brown, tan, and sometimes red or blue
D: Diameter is larger than 6 mm (size of a pencil eraser)

41. Partial-Thickness Burns
First degree
Epidermal damage only
Localized redness, edema (swelling), and pain
Second degree
Epidermal and upper dermal damage
Blisters appear

42. 1st degree
burn
2nd degree
burn
(a)
Skin bearing partial
thickness burn (1st and
2nd degree burns)

43. Full-Thickness Burns Third degree Entire thickness of skin damaged
Gray-white, cherry red, or black
No initial edema or pain (nerve endings destroyed)
Skin grafting usually necessary

44. 3rd
degree
burn
(b)
Skin bearing full
thickness burn
(3rd degree burn)