Download Ch. 4 Skin and Body Membranes

Epithelial Membranes
Cutaneous
membrane
(skin)
(a) Cutaneous membrane (the skin)
covers the body surface.
Figure 4.1a
Epithelial Membranes
Mucous membranes
Mucosa
 Lines
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
(b) Mucous membranes line body cavities
open to the exterior.
Figure 4.1b
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
Parietal
peritoneum
Parietal
pleura
Visceral
pleura
Visceral
peritoneum
Parietal
pericardium
Visceral
pericardium
Figure 4.1c
Skin (Integument)

Consists of three major regions
1. Epidermis—superficial region
2. Dermis—middle region
3. Hypodermis —deepest region

Mostly adipose tissue
Epidermis
Papillary
layer
Dermis
Reticular
layer
Hypodermis
Epidermis
 Keratinized stratified squamous epithelium
 Cells of epidermis
 Keratinocytes—produce fibrous protein keratin
 Melanocytes
 Produce pigment melanin
Stratum corneum
Stratum granulosum
Stratum spinosum
Stratum basale
(a)
Dermis
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
Layers of the Epidermis: Stratum
Spinosum
 ~5-6 cell layers
 Flatter cells increasingly filled with
keratin
Layers of the Epidermis: Stratum
Granulosum
 2-3 cell layers
 Thin layer of flat cells increasingly filled with
keratin
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
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
Stratum corneum
Keratinocytes
Stratum granulosum
Stratum spinosum
Stratum basale
Dermis
(b)
Melanin granule
Melanocyte
Sensory
nerve ending Epidermal
Tactile
dendritic cell
(Merkel) cell
Figure 5.2b
Dermis
Made up of Two layers:
Papillary Layer
Reticular Layer
Epidermis
Papillary
layer
Dermis
Reticular
layer
Hypodermis
Layers of the Dermis: Papillary
Layer
 Papillary layer
 Composed of:
 Contains dermal papillae which may have:
Capillary loops
 Meissner’s Corpuscles
 Free nerve endings

Hair shaft
Epidermis
Papillary
layer
Dermis
Reticular
layer
Hypodermis
(superficial fascia)
Nervous structures
• Sensory nerve fiber
• Pacinian corpuscle
• Hair follicle receptor
(root hair plexus)
Dermal papillae
Subpapillary
vascular plexus
Pore
Appendages
of skin
• Eccrine sweat
gland
• Arrector pili
muscle
• Sebaceous
(oil) gland
• Hair follicle
• Hair root
Cutaneous vascular
plexus
Adipose tissue
Layers of the Dermis: Reticular
Layer
 Reticular layer
 Composed of:
 Most glands, hair follicles, emerge from
dermis
Skin Color
 Three pigments contribute to skin
color:
1. Melanin

Yellow to reddish-brown to black,
responsible for dark skin colors
Skin Color
2. Carotene

Yellow to orange, most obvious in the
palms and soles
3. Hemoglobin

Responsible for the pinkish hue of
skin
Appendages of the Skin
Derived from the epidermis
Sweat glands
Oil glands
Hairs and hair follicles
Nails
Sweat Glands
 Two main types of sweat glands
1. 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
Sweat pore
Eccrine
gland
Sebaceous
gland
Duct
Dermal connective
tissue
Secretory cells
Sweat Glands
2. Apocrine sweat glands—confined to
axillary and anogenital areas
 Sebum: sweat + fatty substances and
proteins
 Ducts connect to hair follicles
 Functional from puberty onward
Sebaceous (Oil) Glands
Most develop from hair follicles
Secrete Sebum:
Oily secretion
Bactericidal
Softens hair and skin
Sweat
pore
Dermal
connective
tissue
Sebaceous
gland
Sebaceous
gland duct
Eccrine
gland
Hair in
hair follicle
Secretory cells
Figure 4.6
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
Follicle wall
Hair shaft
Arrector
pili
Sebaceous
gland
Hair root
Hair bulb
Hair
• Cuticle
• Cortex
• Medulla
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
Hair Follicle
Arrector pili
Smooth muscle attached to
follicle
Contraction of these muscles
causes the hairs to stand on
end
Hair shaft
Arrector
pili
Sebaceous
gland
Hair root
Hair bulb
Follicle wall
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
Structure of a Nail
Scalelike modification of the
epidermis
Structures of the nail: Nail matrix,
nail bed, hyponichium,
eponichium,
Lateral
nail fold
Lunule
(a)
Free edge Body
of nail
of nail
Eponychium
(cuticle)
Nail bed
Proximal
nail fold
Root of nail
Nail
matrix
(b)
Hyponychium
Phalanx (bone of fingertip)
Functions of the Integumentary
System
1. 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
Functions of the Integumentary
System
Body temperature regulation
2.

At elevated temperature, dilation of dermal vessels
and increased sweat gland activity cool the body
Cutaneous sensations
3.

Temperature, touch, and pain
Functions of the Integumentary
System
Metabolic functions
4.

5.
6.
Synthesis of vitamin D precursor
Blood reservoir—up to 5% of body’s blood volume
Excretion—nitrogenous wastes and salt in sweat
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
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
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
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)
Figure 5.8c
Partial-Thickness Burns
 First degree
 Epidermal damage only

Localized redness, edema (swelling),
and pain
 Second degree
 Epidermal and upper dermal damage

Blisters appear
1st degree
burn
2nd degree
burn
(a) Skin bearing partial
thickness burn (1st and
2nd degree burns)
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

3rd
degree
burn
(b) Skin bearing full
thickness burn
(3rd degree burn)