so what does the skin do?
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So What Does The Skin Do?. 32.7 Vertebrate Skin— Example of an Organ System. Skin is the body’s interface with the environment Sensory receptors, barrier against pathogens, internal temperature control, water conservation - PowerPoint PPT PresentationTRANSCRIPT
So What Does The Skin Do?
32.7 Vertebrate Skin—Example of an Organ System
Skin is the body’s interface with the environment• Sensory receptors, barrier against pathogens,
internal temperature control, water conservation
Vertebrate skin is made up of all four tissue types arranged in two layers: • Outer epidermis contain keratinocytes• Deeper dermis contains nerves, blood and lymph
vessels, hair follicles and glands
Epidermis – epithelial tissuea. stratum germinativum – wavy ridges extend from dermis, stem cells regenerate skin takes ~ 14d- as cells move outward they gain keratin b. stratum corneum – dead outer layer (~ 14 d) Skin Color – melanin & blood supply.
Fig. 32-13b, p. 548
outer flattened epidermal cells
cells being flattened
dividing cells
dermis
Dermis – contains accessory structuresa. Hair papilla at base of follicle adds keratin- contains blood vessels and nerves (sensation)- arrector pili makes hair stand on end b. Sebaceous glands – sebum lubricates hair & inhibits bacteria. Activated at puberty. - May clog & form acne c. Sweat glands – secretes water, salt & substances that produce body odor
Fig. 32-13a, p. 548
hair
epidermis
dermis
hypodermis
sensory neuronoil gland
hair follicle sweat gland
blood vessels smooth muscle
Fig. 32-13c, p. 548
hair’s cuticle
one hair cell
keratin macrofibril
keratin polypeptide chain
Sunlight and Human Skin
Melanocytes in skin make a brown pigment (melanin) which affects skin color and tanning
Melanin protects against UV radiation• A little UV promotes vitamin D production• A lot of UV damages DNA and promotes cancer
Nails – can be used as an indicator for circulation.- WHAT IS CLUBBING?
32.8 Farming Skin
Commercially grown skin substitutes are already in use for treatment of chronic wounds
Skin may be a source of stem cells that could be used to grow other organs
http://apbrwww5.apsu.edu/thompsonj/Anatomy%20&%20Physiology/2010/2010%20Exam%20Reviews/Exam%202%20Review/Ch%205%20Burns.htm
32.7-32.8 Key Concepts A Closer Look at Skin
Skin is an example of an organ system
It includes epithelial layers, connective tissue, adipose tissue, glands, blood vessels, and sensory receptors
It helps protect the body, conserve water, control temperature, excrete wastes, and detect external stimuli