BODY MEMBRANES

EPITHELIAL MEMBRANES

•Cutaneous

•Mucous

•Serous

Cutaneous Membranes• Skin• Composed of two layers

- Epidermis

- Dermis = dense connective

- Hypodermis (subcutaneous)= adipose layer under dermis; (not considered part of the skin)

Mucus membranes (mucosa)

• Moist, line cavities that open to the outside of body

• Most secrete mucus

• Rests on loose connective tissue membrane (lamina propria)

Serous membrane (serosa)

• lines cavities that do not open to the outside

• self-enclosed

• Inner space is filled with serous fluid

• Supports and allows movement of the organs in the cavity

• Visceral serosa = side that contacts organs

• Parietal serosa = side attached to cavity wall

Serous Membranes• Peritoneum: lining abdominal

cavity and covering its organs

• Pleura: surrounds lungs

• Pericardium: surrounds heart

Synovial membranes

• Connective tissue membranes that cushion and lubricate bone movements

• Line and lubricate joint cavities (the space between bones)

• Composed of soft areolar tissue

FUNCTIONS OF SKIN

• Thermoregulation – heat loss/retention

• Excretion of urea and uric acid

• Synthesizes vitamin D – via sunlight

• Protection from: – Mechanical damage - UV radiation

– Chemical damage -thermal damage

– Bacteria - desiccation

The Structure of Skin

EPIDERMIS• Keratinized stratified squamous

epithelium (keratin fibers made from KERATINOCYTES)

• Composed of 5 layers called STRATA

• Avascular – shaving may not cause bleeding (unless you cut into dermal layer)

STRATA (deepest superficial)

1. Stratum basale:

closest to dermis the only epidermal cells that receive

adequate nourishment via diffusion of nutrients from dermis

cells constantly undergoing mitosis millions of cells produced daily cells pushed upward toward surface

2.Stratum spinosum - several layers of cells with

large, oval centrally located nuclei and spiny processes

- limited mitosis - most cells dying and being

moved toward surface

3. Stratum granulosum

•One or more layers of granular cells

•Shriveled nuclei

•Contains keratin

4. Stratum lucidum• Thin, clear layer

• No remaining living cells• Present only in the thick skin of

the palms and soles (hairless and extra thick skin)

5. Stratum corneum• 20 to 30 cell layers thick

• Outermost layer

• Cornified or horny cells (completely filled with keratin)

• Rubs and flakes off slowly and steadily

• Replaced by cells from stratum basale• We have totally new epidermis every 25-45

days

Melanin• Produced by melanocytes found

in stratum basale• Ranges in color from yellow to

brown to black• Sun stimulated melanocytes to

produce melanin pigment: TANNING

TANNING• Stratum basale cells

phagocytize the pigment and it accumulates

• Forms protective ‘umbrella’ over superficial side of nuclei

• Shields DNA from UV radiation damage

Excessive Sun Exposure• Causes elastic fibers to clump

(leathery skin)• Depresses immune system

(people w/herpes are more likely to have eruption after sunbathing)

• Skin cancer

• Go to:

•http://www.meddean.luc.edu/lumen/MedEd/Histo/frames/h_fram13.html

Development of a scaffold for dermo-epidermal skin grafts

Hyaluronic acidpolysaccharide, main component of extracellular matrix of all connective tissue particularly present in the dermisinvolved in the processes of tissue repair.

Processable biomaterial, which may be transformed in several physical forms: -fibers-Membranes-Microspheres-Tridimensional matrices.

HYAFF® Tridimensional matrix, utilized as scaffold to growth the cells of the skin in the laboratory.

Scanning electron microscope picture of the scaffold utilized to build the "bioengineered" skin.

Cells growing into the tridimensional structure of HYAFF®. These cells are able to form new dermal tissue.

LASERSKIN®: delivery system for the keratinocytes, the epidermal cells which form the external layer of the human skin.

Skin cells growing on the HYAFF® membrane. Through the microperforations the cells are able

to reach the wound bed and to regenerate the epidermis.

Applicationof the bioengineered skin on a foot ulcer