INTEGUMENTARY SYSTEM
“beauty is only skin deep…”
Body Membranes
• Epithelial Membranes: covering and lining
membranes include:
– Cutaneous membrane (skin)
– Mucus membrane
– Serous membrane
• They all have an underlying layer of
connective tissue
Cutaneous and Mucus
Membranes
Cutaneous Membrane
• Skin
• Superficial layer is keratinized stratified
squamous
• Underlying layer is dense fibrous
connective tissue.
• Exposed to air making it a dry membrane
Mucous membrane
• Composed of epithelium resting on a loose
connective tissue membrane called a
lamina propria.
• Lines body cavities that open to the
exterior: respiratory, digestive, urinary, and
reproductive tracts.
• Wet or moist membranes that are
continuously bathed in secretions or urine
Serous Membranes
Serous Membrane
• Epithelium resting on a thin layer of
areolar connective tissue.
• Line membranes that are closed to the
exterior (except for the dorsal body cavity
and joint cavities)
• Occur in pairs:
– Parietal layer: outermost layer, fold in on itself
to create the:
– Visceral layer: layer closest to the organ
Parietal vs Visceral
Connective Tissue Membrane
• Synovial Membrane: composed of soft
areolar connective and has no epithelial.
• Line the fibrous capsules surrounding
joints
• Provide a smooth surface and secrete a
lubricating fluid
• Cushion organs moving against each
other during muscle activity.
Synovial Membrane
SKIN
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surface area: 1.2-2.2 square meters
considered the largest organ of the body
7% of total body weight (9-11 pounds)
varies in thickness from 1.5-4.0 mm
epidermis replaced every 25-45 days
thick skin-covers palms, fingertips, soles of
feet (5 epidermal layers)
• thin skin-covers the rest of the body (4
epidermal layers)
SKIN
• epidermis
– outermost protective shield
– epithelial cells
– nonvascular
• dermis
– leathery (hide)
– fibrous connective tissue
– vascular
• hypodermis (subcutaneous tissue)
– deepest layer
– adipose tissue (fat cells)
CELLS OF THE EPIDERMIS
• keratinocytes
– most numerous epidermal cell
– produce keratin—fibrous protein
• waterproof, tough protective covering
– tightly connected by desmosomes
• melanocytes
– found in stratum basale
– produce pigment melanin—uv protection for
keratinocytes
cells (cont)
• Langerhan’s cells
– macrophages
– play role in immunity
• Merkel cells
– sensory receptor for touch
LAYERS OF THE EPIDERMIS
• stratum corneum (horny layer)
– outermost layer; dead, keratinized cells
• stratum lucidum (clear layer)
– found in thick skin only
– thin translucent band
• stratum granulosum (granular layer)
– change in keratinocytes—flattened cells w/ granules
• stratum spinosum (spiny layer)
– ‘prickles’ irregular shape of keratinocytes
– bundles of pre-keratin filaments
• stratum basale (basal layer)
– mostly single row of cells; site of mitotic cell division
– 10-25% are melanocytes
Dermis
• Second major skin region containing
strong, flexible connective tissue
• Cell types include fibroblasts,
macrophages, and occasionally mast cells
and white blood cells
• Composed of two layers – papillary and
reticular
DERMIS
• papillary layer
– areolar connective tissue
– peglike projection: dermal papillae
– free nerve endings, Meissner’s corpuscles,
Pacinian corpuscles
– dermal ridgesepidermal ridgesfingerprints
• reticular layer
– 80% of the thickness of dermis
– dense irregular connective tissue
– important cleavage or tension lines--surgery
Functions of the Integumentary
System
• Protection – chemical, physical, and
mechanical barrier
• Body temperature regulation is
accomplished by:
– Dilation (cooling) and constriction (warming)
of dermal vessels
– Increasing sweat gland secretions to cool the
body
• Cutaneous sensation – exoreceptors
sense touch and pain
Functions of the Integumentary
System
• Metabolic functions – synthesis of vitamin
D in dermal blood vessels
• Blood reservoir – skin blood vessels store
up to 5% of the body’s blood volume
• Excretion – limited amounts of nitrogenous
wastes are eliminated from the body in
sweat
Skin Color
• Three pigments contribute to skin color
– Melanin – yellow to reddish-brown to black
pigment, responsible for dark skin colors
• Freckles and pigmented moles – result from local
accumulations of melanin
– Carotene – yellow to orange pigment, most
obvious in the palms and soles of the feet
– Hemoglobin – reddish pigment responsible for
the pinkish hue of the skin
Skin Cancer
• The three major types of skin cancer are:
– Basal cell carcinoma
– Squamous cell carcinoma
– Melanoma
Basal Cell
Carcinoma
• Least malignant and most common skin
cancer
• Stratum basale cells proliferate and invade
the dermis and hypodermis
• Slow growing and do not often
metastasize
• Can be cured by surgical excision in 99%
of the cases
Squamous
Cell Carcinoma
• Arises from keratinocytes of
stratum spinosum
• Arise most often on scalp, ears,
and lower lip
• Grows rapidly and metastasizes if
not removed
• Prognosis is good if treated by
radiation therapy or removed
surgically
Melanoma
• Cancer of melanocytes is the most
dangerous type of skin cancer because it
is:
– Highly metastatic
– Resistant to chemotherapy
Melanoma
• Melanomas have the following
characteristics (ABCD rule)
– A: Asymmetry; the two sides of the
pigmented area do not match
– B: Border is irregular and exhibits
indentations
– C: Color (pigmented area) is black, brown,
tan, and sometimes red or blue
– D: Diameter is larger than 6 mm (size of a
pencil eraser)
Skin and Aging
• Epidermal replacement of cells slows and skin
becomes thinner
• Skin becomes dry and itchy
• Subcutaneous fat layer diminishes, leading to
intolerance of cold
• Decreased elasticity and loss of subcutaneous
tissue leads to wrinkles
• Decreased numbers of melanocytes and
Langerhans’ cells increase the risk of skin
cancer
A
B
C
D
E
Burns
• First-degree – only the epidermis is damaged
– Symptoms include localized redness, swelling,
and pain
• Second-degree – epidermis and upper
regions of dermis are damaged
– Symptoms mimic first degree burns, but blisters
also appear
• Third-degree – entire thickness of the skin is
damaged
– Burned area appears gray-white, cherry red, or
black; there is no initial edema or pain (since
nerve endings are destroyed)
Anatomy-Physiology
Start: midterm exam on Thurs—copy topics
• body systems
• homeostasis—negative & positive feedback mechanisms
• directional terms & body planes
• cells—plasma membrane, cell transport, membrane junctions
• osmosis—hypo, hyper, isotonic solutions
• tissue types
• integumentary system
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–
–
–
–
functions
epidermal layers
dermis
skin appendages—hair, nails, sweat glands
skin cancer
Objectives:
• notes: integumentary system
• work on Chap. 5 study guide—due Thurs