Tyus 1
Chelsea Tyus
Dr. Fitch
Biology 168.0007
27 April 2017
The Integumentary System and Modifications to Two Problems that
Affect the Integumentary System
Like all systems of the human body, the integumentary system is very important
in various ways. It provides protection from the outside environment and foreign
substances or microorganisms from entering the body. It keeps fluids within the body. It
houses millions of nerves and pain receptors for sensation and feeling. It aids in the
production of vitamin D and temperature regulation. It disposes of wastes through
excretion.
The integumentary system or skin, is made up of two main layers: the dermis and
epidermis. In these layers are other intricate structures like hair follicles, sweat glands,
sebaceous glands, etc. The hypodermis or subcutaneous layer, lies underneath the
dermis and is composed mostly of fatty tissue. This layer isn’t technically considered a
part of the skin but is still important as it connects the skin to the muscle and bones. The
epidermis is the superficial layer, with the dermis beneath. The epidermis is made up of
stratified squamous epithelia and on the outermost surface the epithelia consists of
keratinized cells such as Langerhans cells, melanocytes, and Merkel cells. The dermis is
made up of two connective tissue layers: loose (papillary), and dense irregular
(reticular). The dermis houses fibroblasts, collagen, elastin, blood vessels, and sensory
Tyus 2
receptors. Since the dermis is composed of connective tissue, it can retract and stretch.
It is also where the nerves are (fileserver.net)
The epidermis is composed of five sub-layers. The first is the stratum corneum,
the outermost of all the layers. This layer is composed of about twenty-five layers or
more of dead squamous cells. Since it receives the most exposure and is susceptible to
abrasion it has to be highly mitotic. Its functions are the production of vitamin D,
protection against abrasion, ultraviolet light, and chemicals/microorganisms.
The next layer is the stratum lucidum. It appears to be transparent, hence the
name ‘lucidum’. It is composed of three to five layers of dead cells. It functions by
excreting keratohyalin around keratin fibers (Vanputte, et al.).
Stratum granulosum comes next. This is composed of two to five layers of flat
cells in the shape of diamonds. It produces keratohyalin granules (Vanputte, et al.).
The layer after that is stratum spinosum. Composed of eight to ten layers of
different-shaped cells, its functions are producing keratin fibers and in turn, the
lamellar bodies form inside keratinocytes (Vanputte, et al.).
The last layer is the stratum basale. It is composed of a single layer of columnar
and/or cuboidal cells. It functions to produce cells of superficial strata and is where
melanocytes are produced (Vanputte, et al.).
There are two types of skin within the epidermis: thick skin and thin skin. Thick
skin has all of the five epithelial strata and is found in select areas such as the soles of
the feet, the hands, and the fingers, areas that are prone to constant friction. Hair does
not grow in places where there is thick skin. Thin skin is found anywhere else on the
body (Vanputte, et al.).
Tyus 3
The dermis plays a large role in the fighting of infections, regulating temperature,
and supplying nutrients (Bailey, Regina). Besides the structures and glands named
earlier, the dermis also contains the lymph vessels, which produce a white fluid
containing white blood cells, and is where the sweat glands and sebaceous glands are
located. The dermis is composed of two tissues layers, which are the superficial papillary
layer, so named after the bumpy protrusions that extend from it called dermal papillae,
and the deeper reticular layer (Vanputte, et al).
Sometimes when we think of the integumentary system only the skin comes to
mind, but the hair and nails are also an essential part, and not just for aesthetic
purposes. The hair and nails are called the accessory structures of the integumentary
system.
