Chapter 4 Outline

Chapter 4. The Integumentary System & Body Membranes

1) Body Membranes
a) Functions:
i) Covers body surfaces
ii) Lines body cavities
iii) Forms protective sheets around organs
b) Classification
i) Epithelial membranes:
• Cutaneous
• Mucous
• Serous
ii) Connective tissue:
• Synovial membranes – joint cavities
c) Cutaneous = skin
i) Dry membrane
ii) Outermost protective boundary
iii) Superficial epidermis is composed of keratinized stratified squamous epithelium
iv) Underlying dermis is mostly dense connective tissue
d) Mucous = digestive & respiratory interior surfaces
i) Surface epithelium type depends on site:
ii) Stratified squamous epithelium (mouth, esophagus)
iii) Simple columnar epithelium (rest of digestive tract)
iv) Underlying loose connective tissue
v) Lines all body cavities that open to the exterior body surface (digestive & respiratory sytems)
vi) Often adapted for absorption or secretion
e) Serous – internal: visceral & parietal
i) Surface is a layer of simple squamous epithelium
ii) Underlying layer is a thin layer of areolar connective tissue
iii) Lines open body cavities that are closed to the exterior of the body
iv) Serious membranes occur in pairs separated by serous fluid:
• Visceral layer covers the outside of the organ
 Peritoneum (abdominal)
 Pleura (lungs)
 Pericardium (heart)
• parietal layer lines a portion of the wall of ventral body cavity
 Peritoneum (abdominal)
 Pleura (lungs)
 Pericardium (heart)
f) Synovial – connective tissue only
i) Lines fibrous capsules surrounding joints
ii) Secretes a lubricating fluid
2) The Integumentary System
a) Skin (or cutaneous membrane) and derivatives
b) Skin derivatives:
i) Sweat glands
ii) Oil glands
iii) Hair
iv) Nails
c) Structure of the Integumentary System
i) Epidermis – outer layer
• Stratified squamous epithelium
• Often keratinized (hardened by keratin)
ii) Dermis
• Dense connective tissue (mainly collagen)
• Blisters develop between E and D
iii) Hypodermis (subcutaneous tissue) is deep to dermis:
• Not part of skin
• Anchors skin to underlying organs
• Composed mostly of adipose tissue
iv) Strata or layers of the epidermis (See Fig. 4.3)
 Stratum basale (germinating layer)
 Deepest layer of epidermis
 Lies next to dermis
 Cells undergoing mitosis
 Daughter cells are pushed upward to become the more superficial layers
 Stratum spinosum (prickly layer) – becoming more squamous
 Stratum granulosum (granular layer) – becoming imbedded with keratin
 Stratum lucidum (clear layer)
 Formed from dead cells of the deeper strata
 Occurs only in thick, hairless skin of the palms of hands and soles of the feet
 Stratum corneum (horny layer)
 Outermost layer of epidermis, ¾ of it’s thickness
 Shingle-like dead cells are filled with keratin (protective protein prevents water loss from skin)
v) Melanin
• Pigment (melanin) produced by melanocytes
• Melanocytes are mostly in the stratum basale
• Color is yellow to brown to black
• Amount of melanin produced depends upon genetics and exposure to sunlight
 Albino = no melanin
vi) The Dermis (See Fig. 4.4)
• Characteristics
• Layers of the dermis
 Papillary layer (upper demal region)
 Projections called Dermal papillae
1. Some contain capillary loops
2. Other house pain receptors and touch receptors
 Reticular layer (deepest skin layer)
 Blood vessels
 Sweat and oil glands
 Deep pressure receptors
• Collagen & elastic
 Located throughout dermis
 Collagen = toughness
 Elastic = elasticity
• Blood vessels play a role in body temperature regulation
vii) Hypodermis
3) Skin Color
a) Pigments
i) Melanin
• Yellow, brown, or black pigments
ii) Carotene
• Orange-yellow pigment from some vegetables
iii) Hemoglobin
• Red coloring from blood cells in dermal capillaries
• Oxygen content determines the extent of red coloring

4) Appendages (something that sticks out) of the skin
a) Glands (See Fig. 4.6)
i) Sebaceous or oil glands
• Lubricant for skin
• Prevents brittle hair
• Kills bacteria
• Most have ducts that empty into hair follicles; mother open directly into skin surface
• Glands are activated at puberty
• Sebum
ii) Sweat glands: produces sweat, located all over body
Odor is from breakdown by associated bacteria
• Composition
 Mostly water
 Salts and vitamin C
 Some metabolic waste
 Fatty acids and proteins (apocrine only)
• Function
 Helps dissipate excess heat
 Excretes waste products
 Acidic nature inhibits bacteria growth
• Two types:
 Eccrine
 Open via duct to pore on skin surface
 All over body, produce sweat
 Apocrine
 Ducts empty into hair follicles
 Axillary & genital areas, mysterious
• Ceruminous glands
• Mammary glands
b) Nails (See Fig. 4.9)
- Scale-like modifications of the epidermis (heavily keratinized)
- Stratum basale extends beneath the nail bed (responsible for growth)
- Lack of pigment makes them colorless
i) Nail structures:
• Free edge
 Body is the visible attached portion
 Root of nail embedded in skin
 Cuticle is the proximal nail fold that projects onto the nail body
ii) Nail bed
iii) Nail matrix
iv) Nail folds
c) Hair (See Fig. 4.7)
- Produced by hair follicle
- Consists of hard keratinized epithelial cells
- Melanocytes provides pigment for hair color
i) Hair anatomy:
• Central medulla
• Cortex surrounds medulla
• Cuticle on outside of cortex
 Most heavily keratinized
ii) Structure
• Follicle
 Dermal and epidermal sheath surrounds hair root
• Root
• Shaft
iii) Arrector pili muscle
• Smooth muscle
• Pulls hair upright when cold or frightened
iv) Concentric layers
• Medulla
• Cortex
• Cuticle
v) Hair follicle (See Fig. 5.5)
• Hair bulb
• Root hair plexus
• Hair papilla
• Hair mat
vi) Hair thinning and baldness – genetic trait
5) Infections
a) Athlete’s foot (tinea pedis)
i) Caused by fungal infection
b) Boils & carbuncles
i) Caused by bacterial infection
c) Cold sores
i) Caused by virus
d) Contact dermatitis
i) Exposures cause allergic reaction
e) Impetigo
i) Caused by bacterial infection
f) Psoriasis
i) Cause is unknown…autoimmune?
ii) Triggered by trauma, infection, stress
6) Burns – tissue damage and cell death caused by heat, electricity, UV radiation, or chemicals
a) Associated dangers:
i) dehydration
ii) electrolyte imbalance
iii) circulatory shock
b) Rule of nines – way to determine the extent of burns
i) Body is divides into 11 areas for quick estimation
ii) Each area represents about 9% of total body surface area
c) Classification of burns
i) First degree
• Only epidermis is damaged
• Skin is red and swollen
ii) Second degree
• Epidermis and upper dermis are damaged
• Skin is red with blisters
iii) Third degree
• Destroys entire skin layer
• Burn is gray=white or black
iv) Fourth degree
v) Critical Burns
• Burns are considered critical if:
 Over 25% of body has second-degree burns
 Over 10% of the body has third-degree burns
 There are third-degree burns of the face, hands, or feet
7) Skin cancer
a) Caner - Abnormal cell mass
b) Classified two ways:
i) Benign
• does not spread (encapsulated)
ii) Malignant
• Metastasized (moves) to other parts of the body
c) Skin cancer is the most common type of cancer
d) Types
i) Basal cell carcinoma
• Least malignant (dangerous)
• Most common type
• Arises from stratum basale
ii) Squamous cell carcinoma:
• Metastasized to lymph nodes if not removed
• Early removal allows a good chance of cure
• Believed to be sun-induced
• Arises from stratum spinosum
iii) Melanoma
• Malignant melanoma:
 Most deadly of skin cancers
 Cancer of melanocytes
 Metastasizes rapidly to lymph and blood vessels
 Detection uses ABCD rule
e) ABCD rule
i) A = asymmetry
• Two sides of pigmented mole do not match
ii) B = border irregularity
• Borders of mole are not smooth
iii) C = color
• Different colors in pigmented area
iv) D = diameter
• Spot is larger than 6mm in diameter