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
Lines body cavities that open to exterior (e.g., digestive and respiratory tracts)

4. (b) Mucous membranes line body cavities open to the exterior.
Mucosa of
nasal cavity
Mucosa of
mouth
Esophagus
lining
Mucosa of
lung bronchi
(b) Mucous membranes line body cavities open to the exterior.
Figure 4.1b

5. 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

6. Parietal peritoneum Parietal pleura Visceral pleura Visceral
pericardium
Visceral
pericardium
Figure 4.1c

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

8. Epidermis
Papillary
layer
Dermis
Reticular
layer
Hypodermis

9. Epidermis Keratinized stratified squamous epithelium
Cells of epidermis
Keratinocytes—produce fibrous protein keratin
Melanocytes
Produce pigment melanin

10. Stratum corneum
Stratum granulosum
Stratum spinosum
Stratum basale
(a)
Dermis

11. Layers of the Epidermis: Stratum Basale
Deepest epidermal layer firmly attached to dermis
One cell layer
Cells undergo rapid division and then travel from basal layer to surface
Takes 25–45 days
Contains melanocytes

12. Layers of the Epidermis: Stratum Spinosum
~5-6 cell layers
Flatter cells increasingly filled with keratin

13. Layers of the Epidermis: Stratum Granulosum
2-3 cell layers
Thin layer of flat cells increasingly filled with keratin

14. 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

15. Layers of the Epidermis: Stratum Corneum
20–30 rows of dead, flat, keratinized cells
Three-quarters of the epidermal thickness
Functions
Protects from abrasion and penetration
Waterproofs skin

16. 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

17. Dermis
Made up of Two layers:
Papillary Layer
Reticular Layer

18. Epidermis
Papillary
layer
Dermis
Reticular
layer
Hypodermis

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

20. 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

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

22. Skin Color Three pigments contribute to skin color: Melanin
Yellow to reddish-brown to black, responsible for dark skin colors

23. Skin Color Carotene Hemoglobin
Yellow to orange, most obvious in the palms and soles
Hemoglobin
Responsible for the pinkish hue of skin

24. Appendages of the Skin Derived from the epidermis Sweat glands
Oil glands
Hairs and hair follicles
Nails

25. 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
Function in thermoregulation

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

27. 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

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

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

30. Hair Functions Alerting the body to presence of objects on the skin
Guarding 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

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

32. 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

33. Hair Follicle Arrector pili Smooth muscle attached to follicle
Contraction of these muscles causes the hairs to stand on end

34. 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)
Diagram of a longitudinal view of the expanded hair
bulb of the follicle, which encloses the matrix
Figure 4.7

35. Structure of a Nail Scalelike modification of the epidermis
Structures of the nail: Nail matrix, nail bed, hyponichium, eponichium,

36. 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)

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

38. 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

39. 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

40. 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

42. 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

44. 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

45. 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)

46. Figure 5.8c

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

48. 1st degree
burn
2nd degree
burn
(a)
Skin bearing partial
thickness burn (1st and
2nd degree burns)

49. 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

50. 3rd
degree
burn
(b)
Skin bearing full
thickness burn
(3rd degree burn)