Skin and Body Membranes I and II
 Types of Body Membranes
 Cutaneous, mucus, serous
 The Integumentary System (Skin)
 Skin Structure (epidermis, dermis)
 Skin Color (pigments and body conditions)
 Appendages of the Skin (oil & sweat, hair, nails)
 Diseases/Injuries to Skin (infections, burns, cancer)
 Changes in the Skin Over a Lifetime
Mucous Membranes: Prone to Dessication
Found lining the inside edges of organs
or tracts that empty into the exterior of
the body
Also:
Urethra
Vaginal tract
Digestive tract, anus
Nostrils
Serous Membranes- Thin linings of organs and body wall
• Parietal serosae line
internal body walls
• Visceral serosae
cover internal organs
Connective Tissue Membrane
 Synovial membrane
Cutaneous Membrane
Functions of the Integumentary System
1.
Protection (chemical, physical, biological)
2.
Body temperature regulation ( perspiration, dermal
vessels)
3.
Cutaneous sensations (temperature, touch, and pain)
4.
Metabolic functions (synthesis of vitamin D precursor and
collagenase; chemical conversion of carcinogens and some
hormones
5.
Blood reservoir—up to 5% of body’s blood volume
6.
Excretion—nitrogenous wastes and salt in sweat
Skin Structure
Epidermis
 Keratinized stratified squamous epithelium
 Cells of epidermis
 Keratinocytes—produce fibrous protein keratin
 Melanocytes
 10–25% of cells in lower epidermis
 Produce brown pigment melanin
 Epidermal dendritic (Langerhans) cells—
macrophages that help activate immune system
 Tactile (Merkel) cells—touch receptors
Detail of Epidermal Skin Structure
Keratinocytes
Stratum corneum
20-30 layers of dead
keratinized cells; glycolipids
in interstitial spaces.
Stratum lucidum
Very thin layer of dead, translucent
keratinocytes; only palms, soles of feet
Stratum granulosum
Three to five layers of flattened
cells,organelles deteriorating;
cytoplasm full of released lipids
Stratum spinosum
Several layers of keratinocytes
unified by desmosomes.
Stratum basale
one row of actively mitotic stem
cells; melanocytes and epidermal
dendritic cells.
Desmosomes
Mnemonic: Basically, the spinning by
granny is loose and corny.
Melanin granule
Melanocyte
Dermis
Sensory
nerve ending
Tactile (Merkel) cell
Epidermal
dendritic
cell
Dermis
 Strong, flexible connective tissue
 Cells include fibroblasts, macrophages, and
occasionally mast cells and white blood cells
 Two layers:
 Papillary
 Reticular
Skin Structure
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
Figure 5.1
Layers of the Dermis: Papillary Layer
 Papillary layer
 Areolar connective tissue with collagen
and elastic fibers and blood vessels
 Dermal papillae contain:
 Capillary loops
 Meissner’s corpuscles (touch se0nsing)
 Free nerve endings .1
Layers of the Dermis: Reticular Layer
 Reticular layer
 ~80% of the thickness of dermis
 Collagen fibers provide strength and
resiliency
 Elastic fibers provide stretch-recoil
properties
 Pacinian corpuscles (pressure and
vibration sensing)
Normal Skin Color Determinants
 Chemicals in the Skin
 Melanin
 Carotene
 Hemoglobin
 Body Conditions
 Erythmea (from embarrassment, fever, tension)
 Pallor/Blanching (stress, etc.)
 Jaundice from liver disease
 Bruises from hematomas
 Cyanosis from low blood oxygen
Appendages of the Skin
 Derivatives of the epidermis
 Sweat glands
 Oil glands
 Hairs and hair follicles
 Nails
Cutaneous Glands: Sebaceous & Sweat
Eccrine (Merocrine)
Sweat Glands
water
salts
Sebaceous glands
(holocrine)
Sebum
- fragmented cells
- fatty acids
- Low pH (antibacterial)
vitamin C
metabolic wastes
ammonia
urea
uric acid
lactic acid
Apocrine sweat glands
confined to axillary and
genital areas
- Sebum: sweat + fatty
substances and proteins
-Ducts connect to hair follicles
-Functional from puberty onward
(as sexual scent glands?)
Specialized apocrine include
- Ceruminous glands
- Mammary glands
Appendages of the Skin: Hair
 Hair and Hair Follicles
Appendages of the Skin: Hair
 Hair follicle
and arrector
pili muscle
Appendages of the Skin: Nails
 Finger Nail and Nail Bed
(Eponychium)
Abnormal or Injured Skin Conditions
 Infections and Allergies of the Skin
 Athletes foot (caused by tinea pedia fungus)
 Boils and carbuncles (caused by inflammation
and/or bacterial infection of oil glands or
follicles
 Cold sores (caused by viruses like Herpes)
 Contact dermatitis (caused by allergic
reaction)
 Impetigo (caused by staph bacteria)
 Psoriasis (scaly skin caused by overproduction
and of cells)
Burns
 Heat, electricity, radiation, certain chemicals

Burn
(tissue damage, denatured protein, cell death)
 Immediate threat:
 Dehydration and electrolyte imbalance,
leading to renal shutdown and circulatory
shock
Abnormal or Injured Skin Conditions
The Rule of Nines for Estimating Burned Surface Area
Burns are
critical if:
• >25% has
second-degree
• >10% has
third-degree
• Any of face,
hands, or feet
with thirddegree
Abnormal or Injured Skin Conditions
Burns
 Only epidermis is damaged
 Skin is red and swollen
 Second degree burns
 Epidermis and upper dermis are
damaged
 Third-degree burns
 Destroys entire skin layer
 Burn is gray-white or black
Full thickness burn
 Skin is red with blisters
Partial thickness burns
 First-degree burns
Abnormal or Injured Skin Conditions
Cancers (Cause: UV, freq. irritation)
 Basal cell carcinoma
 Least dangerous
 Most common type
 Arises from stratum basale
 Squamous cell carcinoma
 Arises from stratum spinosum
 Metastasizes to lymph nodes
 Early removal allows a good
chance of cure
Abnormal Conditions: Skin Cancer Types
 Malignant melanoma
 Most deadly of skin
cancers
 Cancer of melanocytes
 Metastasizes rapidly to
lymph and blood vessels
 Detection uses ABCD
rule
ABCD Rule in Detecting Melanoma
Skin Tags (Acrochordons/ Cutaneous Papillomas)
 Skin tags are benign growths that are not
cancerous
Skin Changes Over a Lifetime
lanugo
milia
acne
dermatitis
vernix caseosa
aging skin