Objective 5

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

Objective 4

List four functions of the integumentary system.


Skin Functions1. Protects deeper tissues from:

Mechanical, Chemical, Bacterial, Thermal damage

Ultraviolet radiation Desiccation (water-proof) Only lipid-based substances can pass

through (some drugs, poison ivy, nail polish remover, etc.)


Skin Functions2. Aids in heat regulation

blood vessels swell to add heat, constrict to conserve heat

3. Aids in excretion of urea and uric acid

through sweat

4. Synthesizes vitamin D to make melatonin and other important body chemicals (“cabin fever”)


Objective 5

Name the tissue types composing the dermis and epidermis; including layers and functions.


Skin Structure Dermis (lowest layer)

Dense connective tissue

Epidermis – outer layer Stratified squamous

epithelium Often keratinized

(hardened by keratin)

Figure 4.3


Skin Structure Deep to dermis is the hypodermis

Not part of the skin Anchors skin to underlying organs Composed mostly of adipose tissue


Skin Structure

Figure 4.4


Dermis Two layers

Papillary layer Projections called dermal papillae Pain receptors Capillary loops

Reticular layer Blood vessels Glands Nerve receptors


Melanin Pigment (melanin) produced by melanocytes Color is yellow to brown to black Melanocytes are mostly found in the stratum

basale Amount of melanin produced depends upon

genetics and exposure to sunlight (tanning)


Layer of Epidermis Stratum basale (“base” – deepest layer)

Cells undergoing mitosis Lies next to dermis

Stratum spinosum Web-like system of filaments

Stratum granulosum 3-5 layers thick Waterproof Last layer with capillaries/blood


Layer of Epidermis Stratum lucidum

Occurs only in thick skin Clear, flat dead cells

Stratum corneum – only layer you can see! Shingle-like dead cells 75% of the epidermis Protection “Beauty is Only Skin Deep?” … All we see are dead cells!!! HAHAHAHA…

Documents

Objective 5