Chapter 6 - Integumentary Sx.
The Skin and Accessory
• The skin is one of the largest organs in the
body and serves many functions. Chief
among them is protection. It also prevents
water loss and regulates body
temperature. It also acts as a general
sense organ for the sense of touch and
• The skin has three layers:
1) Epidermis – composed primarily of stratified
2) Dermis – thicker than the epidermis, this
layer is composed of connective tissue,
smooth muscle, nervous tissue and blood
3) Hypodermis – aka subcutaneous layer, the
hypodermis is composed of areolar tissue
The lowest level of cells in this layer is the foundation of
the entire layer. This layer of cells is called stratum
basale and sits atop the basement membrane. These
cells are closest to the underlying blood supply in the
area and thus receive the best nourishment. These cells
are almost always undergoing cell division and new cells
are pushed up and away from the blood supply. This
rise in successive levels removes the cells farther from
the blood supply and in time they die.
As these epithelial cells rise in layers
many of them undergo the process of
keratinization. During this process the
cytoplasm of the cell is replaced by a
fibrous waterproofing protein called
The successive layers of the epidermis are as
1) Stratum Basale – bottom most layer, mitosis is
2) Stratum Spinosum
3) Stratum Granulosum – keratinization is taking place,
these cells are dying
4) Stratum Lucidum
5) Stratum Corneum – completely keratinized, these
cells are all dead and ready to be shed.
Calluses are a thickening of the epidermis due
to regular friction or pressure.
Melanocytes are specialized cells in the
epidermis that reside in the stratum basale.
They produce a pigment called melanin that
provides skin color.
Melanocytes are stimulated by ultraviolet
radiation to produce melanin that absorbs some
of that form of radiation.
**Skin cancer is the most common form of cancer and usually poses the least
threat to life and health. If caught early it is usually very easily treated and
exhibits very little incidence of return.
• Basal Cell Carcinoma – the most common form of skin cancer, this lesion is
benign and very seldom metastasizes (spreads) to distant sites.
• Squamous Cell Carcinoma – the next most common form of skin cancer,
this carcinoma is almost as reluctant to metastasize as the previous
• Malignant Melanoma – making up only a very small minority of skin cancers
(about 5% or less), but is one of the most dangerous forms of any cancer
known. Caught early it is similar in treatment to the above forms. However,
metastasis of melanoma can be very fast, and once this happens the
survival rate after treatment plummets greatly.
The Dermis is largely composed of connective
tissues with a lot of collagen and elastic fibers.
The dermis has many accessory structures of
the skin located in it.
Nerve endings scattered throughout the dermis
are responsible for the variety of sensation
available thru the skin.
The papillary layer of the dermis is responsible
for fingerprint patterns.
Hair Follicles: Hair grows from epidermal cells
found in the dermis. Growth of hair starts at the
root where blood vessels nourish the hair. The
shaft of hair is made up of keratinized
Hair color is determined by genetics. The more
melanin a person produces, the darker their hair
A bundle of smooth muscle cells called arrector
pili is attached to each hair follicle. This muscle
is responsible for making the hair stand up at
times and thus for goose bumps. Arrector pili
are under autonomic control.
Nails: these structures are made of a special
keratinized epithelium. Each nail has a free
edge, nail plate, nail bed, a lunula and a root or
Skin Glands: the glands in the dermis
are considered exocrine glands as they
possess a duct for secretory purposes.
1) Sebaceous Glands – these glands secrete
body oil known as sebum. These glands are
usually associated with a hair follicle.
Sebum helps the body by keeping the skin
and hair soft, pliable and waterproof. An
underproduction will result in dry skin and
2) Sudoiferous Glands – There are two types of sweat
A. Eccrine – these are the smallest and most numerous
sweat glands. They are found body wide with few
B. Apocrine – larger than eccrine glands, these glands
also secrete sweat. Found only in the axilla, groin,
and around the nipples, apocrine glands do not
become active until puberty. They usually have a
small amount of melanin associated with them, thus
areas containing these glands are slightly darker in
Regulation of Body Temperature
Normal body temperature ranges from
96.5-99.5 degrees F. Average body
temperature is 98.6 degrees F. or 37
Heat in the human body is a product of
metabolic reactions and muscle
Heat is lost from the body in a number of
1) Radiation – loss of heat in the form of
infared energy from a warm surface to
2) Conduction – loss of heat from the body into
an object that is in direct contact with the
3) Convection – The loss of heat from the body due to
the movement of cooler air over the body.
4) Evaporation – the loss of heat from the body by way
of moisture as it leaves the surface of the body as a
The body may retain or release heat thru the action
of the blood vessels. By constricting the diameter of
the superficial vessels the warmth of the blood is
conserved in the body’s core areas such as the
torso and head. Pallor and perhaps cyanosis can
result in this situation. On the other hand, if the
blood vessels are dilated, then more blood reaches
the skin and is loss by means of radiation and
flushing will probably result.
Hypothermia is a condition where the core body
temperature falls below a manageable level. A
gradual re-warming of the body is called for in order to
Hyperthermia is a condition where the core body
temperature rises above a manageable level. Two
types are noted:
1) Heat Exhaustion – a condition that may be easily
managed by cooling of the body as well as the
replacement of body fluids and needed electrolytes.
2) Heat Stroke – a condition that is considered a medical
emergency as it poses a threat to life. The tx. is the
same as above, but will likely need to be done in a
medical setting as the fluids are often administered via
Skin color is due to a variety of factors. Included
are genetics (heritage), environmental factors
(sun exposure or lack of), and physiological
factors (such as flushing and cyanosis).
The three pigments playing into skin color are
melanin, carotene (found in certain foods), and
hemoglobin (found in red blood cells).
Albinism is a condition where a person’s body
does not make any of the melanin pigment.
Inflammation is a response of tissue to
injury. The five signs of inflammation
5) Loss of Function
Burns may be classified into catagories by the depth to
which they penetrate the body:
1) First degree burns are also called superficial partial
thickness burns. They are characterized by a slight
reddening of the skin. The damage does not pass
beyond the epidermis and usually heals within a few
2) Second degree burns are also called a deep partial
thickness burn. These are characterized by blisters.
Second degree burns penetrate thru the epidermis into
the dermis but no farther. Blistering is due to damaged
capillary vessels. These burns are usually quiet painful.
Healing time will usually be at least two weeks, but may
take longer depending on how extensive the damage to
3) Third degree burns are also called full
thickness burns. These burns penetrate
thru the epidermis, thru the dermis, into the
hypodermis and possibly much deeper.
Charring of the tissues is evident in a third
degree burn, but the are of the third degree
burn is without pain as the nerve endings in
the area are destroyed. Healing time can be
quite extensive and surgical grafts are
frequently used to assis in the process.
Burn patients are assessed using the rule
of nines. This is a system by which the
body is assigned an amount of surface are
based on size. See chart p.187.