The Integumentary
System
Skin
Jasmine Gallup, Tony Li,
Michael Ivanov, Ben Jones
The Basics
DermisInnermost layer, contains
blood vessels, nerves,
sweat glands, hair
follicles, and smooth
muscles
 EpidermisOutermost layer, rapid cell
division leads to a tough
waterproof outer layer
which is constantly
replaced, contains
melenin*
* a pigment that protects the
body from UV radiation

Functions1. Is a protective covering
for the body and a
sensory organ
2. Regulates body
temperature
3. Produces vitamin D
4. Protects the body from
UV radiation
Amphibia
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Many amphibians must keep their skin moist at
all times because it is their primary respiratory
organ. The skin is membranous and oxygen can
be absorbed directly into the bloodstream.
Mucous glands in the skin help keep
amphibians’ skin moist.
Amphibians’ skin is very thin and permeable
Agnatha, Chondrichthyes, and
Osteichthyes
Placoid cells, or denticles are tooth-like
scales that cover sharks, rays, and skates.
 These develop from the dermal layer of
the skin
 Many extinct agnatha (jawless fish) had
scales similar to that of sharks, but
nowadays the only covering is skin

Aves
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Birds have a very different type of
skin system than mammals,
mainly because they have
feathers. Feathers aid birds in
flight, waterproofing, and warmth.
They also provide coloration for
communication.
The different types of feathers all
grow from the epidermis layer of
skin. Specifically from regions of
skin known as pterylae. These
feathers are made of a protein
called Beta-keratin.
Plumage- the arrangement and
appearance of feathers on the
body
Sebaceous glands- the glands
that secrete feathers on the skin of
birds
Reptilia
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Reptiles have thick and protective
skin
Their scales are made of keratin,
like that of birds
Both birds and reptiles have few
specified glands. The ones they
do have usually secrete
pheromones.
In birds there is a gland that
secretes an oil which helps with
preening.
Mammalia
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Mammals skin is the most complex system
Underneath the layer of skin we have a layer of
insulation (fat) that conserves heat. This layer is called
the hypodermis.
Besides that, as we already know, there are two other
layers the epidermis and dermis.
This skin system is complex simply because of the many
specialized glands that mammals posses. Other animals
do not posses these glands.
Mammals also have hair, a defining characteristic of this
Phylum