SKIN

The skin is an ever-changing organ that contains many specialized cells and structures. The skin
functions as a protective barrier that 1. ______________ with a sometimes-hostile environment. It
is also involved in maintaining the 2._____________ temperature for the body to function well. It
gathers sensory information from the environment, and plays an active role in the 3.
_________________ system protecting us from disease. Understanding how the skin can function in
these many 4. _________________starts with understanding its structure.

The epidermis is the outer 5. _____________ of skin. The thickness of the epidermis varies in
different types of skin. It is the thinnest on the eyelids at .05 mm and the thickest on the palms
and soles at 1.5 mm. The epidermis contains 5 layers. The 6. ___________ layer, the stratum basale,
has cells that are 7. _____________ like columns. In this layer the cells divide and push already
formed cells into higher layers. As the cells move into the higher layers, they    8.
____________and eventually die. The top layer of the epidermis, the stratum corneum, is made of
dead, flat skin cells that 9. ____________ about every 2 weeks. There are three types of
specialized cells in the epidermis: the melanocyte produces 10. ___________ (melanin), the
Langerhans' cell is the frontline defence of the 11. ___________system in the skin, and the
Merkel's cells whose function is not 12.__________ known.

The dermis also varies in thickness 13. _________________ on the location of the skin. It is .3 mm
on the eyelid and 3.0 mm on the back. The dermis is 14. __________ of three types of 15.
___________ that are present throughout - not in layers: collagen, elastic tissue and reticular
fibres. The two layers of the dermis are the papillary and reticular layers. The                16.
_____________, papillary layer, contains a thin arrangement of collagen fibres. The lower,
reticular layer, is thicker and made of thick collagen fibres that are 17. ____________ parallel to
the surface of the skin.

The dermis contains many specialized cells and structures. The hair follicles are situated here
with the erector pili muscle that 18. __________ to each follicle. Sebaceous glands and apocrine
glands are associated with the follicle. This layer also contains eccrine sweat glands, but they
19. __________ associated with hair follicles. Blood vessels and nerves course         20.
_____________ this layer. The nerves transmit 21. ________________ of pain, itch, and temperature.
There are also specialized nerve cells called Meissner's and Vater-Pacini corpuscles that transmit
the sensations of touch and pressure.

The subcutaneous tissue is a layer of fat and 22. ___________ tissue that houses larger blood
vessels and nerves. This layer is important is the regulation of 23. ____________ of the skin
itself and the body. The size of this layer  24. _____________ throughout the body and from person
to person.

The skin is a 25. _________________ structure with many functions. If any of the structures in the
skin are not working properly, a rash or abnormal sensation is the result. The whole specialty of
dermatology is devoted to understanding the skin, what can go wrong, and what to do if something
does go wrong.


varies                      are not             connective         complicated         through

proper                      ways                     shed
depending                   upper

                   bottom                      immune (2x)                      clearly
      composed

shaped               pigment              tissue                   arranged
sensations

                interfaces              layer                 flatten
attaches             temperature