Chapter 4 Integumentary

Chapter 4 The Integumentary System & Body Membranes

1) Body Membranes
a) Functions-
• Covers body surfaces
• Line body cavities
• Form protective sheets around organs

b) Classification
i) Epithelial-
ii) Connective tissue
c) Cutaneous = skin
• Dry membrane
• Outermost protective boundary
• Superficial epidermis composed of keratinized stratified squamos epithelium
• Underlying dermis is mostly dense connective tissue
d) Mucous = digestive & respiratory interior surfaces
• Surface epithelium type depends on site-
• Stratified squamous epithelium (mouth esophagus)
• Simple columnar epithelium (rest of digestive tract)
• Underlying loose connective tissue
• Lines all body cavities that open to the exterior body surface (digestive & respiratory systems)
• Often adapted for absorption or secretion
e) Serous – internal: visceral & parietal
• Surface is a layer of simple squamous epithelium
• Underlying layer is a thin layer of areolar connective tissue
• Lines open body cavities that are closed to the exterior of the body
• Serous membranesoccour in pairs separated by serous fluid:
• Visceral layer covers the outside of the organ
• Parietal layer lines a portion of the wall of ventral body cavity
i) Peritoneum
ii) Pleura
iii) Pericardium
f) Synovial – connective tissue
2) The Integumentary System
a) Definition: skin and derivitives
b) Structure of the Integumentary System
i) Epidermis
• Stratified squamous epithelium
• Oftern keratinized (hardened by keratin)
ii) Dermis
• Dense connective tissue (mainly collagen)
• Blisters develop between E and D
iii) Hypodermis
iv) Strata or layers of the epidermis (See Fig. 4.3)
(a) Stratum basale (germinating layer)
(i) Deepest layer of epidermis
(ii) Lies next to dermis
(iii) Cells undergoing mitosis
(iv) Daughter cells are pushed upward to become the more superficial layers
(b) Stratum spinosum (prickly layer)
(i) Become more squamous
(c) Stratum granulosum (granular layer)
(i) Becoming imbedded with keratin
(d) Stratum lucidum (clear layer)
(i) Formed from dead cells of the deeper strata
(ii) Occurs only in thick, hairless skin of the palms of the hands and soles of the feet
(e) Stratum corneum (horny layer)
(i) Outermost layer of epidermis, ¾ of its thickness
(ii) Shingle-like dead cells are filled with keratin (protective protein prevents water loss from skin)
v) Melanin
(1) Pigment (melanin) produced by melanocytes
(2) Melanocytes are mostly in the stratum basale
(3) Color is yellow to brown to black
(4) Amount of melanin produced depends upon genetics and exposure to sunlight
(a) Albino- no melanin
vi) The Dermis (See Fig. 4.4)
(1) Characteristics
(2) Layers of the dermis
(a) Papillary layer
(i) Dermal papillae- some contain capillary loops
- other house pain receptors and touch receptors
(b) Reticular layer
(i) Blood vessels
(ii) Sweat and oil glands
(iii) Deep pressure receptors
(3) Collagen (toughness) & elastic (elasticity)
(a) Located throughout the dermis
(4) Blood vessels- plays 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
(1) Red coloring from blood cells in dermal capillaries
(2) Oxygen content determines the extent of red coloring

4) Appendages of the skin
a) Glands (See Fig. 4.6)
i) Cutaneous glands are all exocrine glands
ii) Sebaceous or oil glands
(1) Produce oil
(2) Prevents brittle hair
(3) Kills bacteria
(4) Most have ducts that empty into hair follicles others open directly onto the skin surface
(5) Glands are activated at puberty
(6) Sebum
iii) Sweat glands
(1) Produce sweat
(2) Widely distributed in skin
(3) Merocrine
(4) Ecrine
(a) Open via duct to pore on skin surface
(b) All over body, produce sweat
(5) Apocrine
(a) Ducts empty into hair follicles
(b) Axillary & genital areas, mysterious
(6) Ceruminous glands
(7) Mammary glands
(8) Composition of sweat
(a) Mostly water
(b) Salt and vitamin c
(c) Some metabolic waste
(d) Fatty acids and proteins (apocrine only)
(9) Mammary glands
(10) Function
(a) Help dissipate excess heat
(b) Excretes waste products
(c) Acidic nature inhibits bacteria growth

b) Nails (See Fig. 4.9)
i) Scale-like modifications of the epidermis
(1) Heavily keratinized
ii) Stratum basale extends beneath the nail bed
(1) Responsible for growth
iii) Lack of pigment makes them colorless
iv) Nail structure
(1) Free edge
(2) Body is the visible attached portion
(3) Root of nail embedded in skin
(4) Cuticle is the proximal nail fold that projects onto the nail body

c) Hair (See Fig. 4.7)
i) Produces by the hair follicle
ii) Consists of hard keratinized epithelial cells
iii) Melanocytes provide pigment for hair color
iv) Structure
(1) Root
(2) Shaft
v) Hair anatomy:
(1) Central medulla
(2) Cortex surrounds the medulla
(3) Cuticle on outside of cortex
(a) Most heavily keratinized
vi) Arrector pili muscle-
(1) Smooth muscle
(2) Pulls hair upright when cold or frightened
vii) Concentric layers
(1) Medulla
(2) Cortex
(3) Cuticle
viii) Hair follicle (See Fig. 5.5)- dermal and epidermal sheath surround hair root
(1) Hair bulb
(2) Root hair plexus
(3) Hair papilla
(4) Hair mat
ix) Hair thinning and baldness – genetic trait
5) Infections
a) Athlete’s foot (tinea pedis)
Caused by fungal infection
b) Boils & carbuncles
i) Cause by bacterial infection
c) Cold sores
i) Caused by virus
d) Infections and allergies:
i) Contact dermatitis- exposures cause allergic reaction
ii) Impetigo- caused by bacterial infection
iii) Psoriasis
(1) Cause is unknown... autoimmune?
(2) Triggered by trauma, infection, stress
6) Burns- tissue damage and cell death caused by heat, electricity, UV radiation, or calcium
a) Associated dangers:
i) Dehydrations
ii) Electrolyte imbalance
iii) Circulatory shock
b) Effects
c) Rule of nines
i) Way to determine the extent of burns
ii) Body is divided into 11 areas for quick estimation
iii) Each surface represents about 9% of total body surface area
d) Classification of burns
i) First degree
(1) Only epidermis is damaged
(2) Skin is red and swollen
ii) Second degree
(1) Epidermis and upper dermis is damaged
(2) Skin is red with blisters
iii) Third degree
(1) Destroys entire skin layer
(2) Burn is gray-white or black
iv) Critical burns
(1) Over 35% of body has second-degree burns
(2) Over 10% of the body had third-degree burns
(3) There are third-degree burns of the face, hands, or feet
7) Skin cancer
a) 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-
(1) Least malignant
(2) Most common type
(3) Arises from stratum basale
ii) Squamous cell carcinoma
(1) Metastasizes to lymph nodes if not removed
(2) Early removal allows a good chance of cure
(3) Believed to be sun-inducted
(4) Arises from stratum spinosum
iii) Melanoma
(1) Most deadly of skin cancers
(2) Cancer of melanocytes
(3) Metastasizes rapidly to lymph and blood vessels
(4) Detection uses ABCD rule
e) ABCD rule
i) A = asymmetry
(1) Two sides of pigmented mole do not match
ii) B = border irregularity
(1) Borders of mole are not smooth
iii) C = color
(1) Different colors in pigment area
iv) D = diameter
(1) Spot larger than 6 mm in diameter