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• 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 ridgesepidermal ridgesfingerprints

• 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

C

D

E

B

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

– functions– epidermal layers– dermis– skin appendages—hair, nails, sweat glands– skin cancer

Objectives:• notes: integumentary system• work on Chap. 5 study guide—due Thurs