1. Integumentary System A comparison of this system in various organisms By Marci Detwiller

2. What is the integumentary system? The integumentary system is the organ system that protects an organism from damage, including the skin, hair, nails, scales, feathers, etc. It functions to protect other organ systems and to provide the sense of touch. It has receptors for pain, pressure, and temperature, which it regulates.

3. Sponge’s Integument The sponge is a unique animal in that its organ systems can be limited to the integument only. Their “skin”, or body wall, consists of two layers of cells. The outer layer is known as the pinacoderm or the epiderm. This layer is made of flat, thin, and tightly packed cells called pinacocytes and other cells that have openings for water to get through called porocytes. The second layer, underneath the first, is called the choanoderm or the gastroderm, and is made up of choanocytes. These are cells found only in sponges. They constantly pump water out from the sponges interior. They also catch nutrients and food particles and assist in reproduction.

4. Earthworm’s Integument The earthworm’s integument is in control of many life processes. First, it is responsible for letting oxygen into the blood. This is done by absorbing oxygen from its surroundings and allowing it diffuse into the blood that passes through the skin layer. The earthworm’s outer layer is always moist because of a special mucous which come from glands in its skin. This mucous is important because it enables microbes to permeate the skin, as well as lining the tunnels it creates and keeping them more solid, which allows for better aeration of the soil. The skin is also sensitive to light, touch, and chemicals and allows the worm to better understand its surroundings. The integumentary system of the earthworm is also essential in allowing it to move, because of a sac in its skin called the setigerous sac which controls the setae. These are bristles which stick out of the worm and allow it to anchor part of its body while it contracts or stretches the other, giving it the ability to move.

5. Frog’s Integument Frogs have a stretchy skin that is water permeable which allows them to drink through their skin. Their skin is often colourful, to warn predators of toxic poisons, or else can be camouflage to keep predators away. Some frogs can change the colour of their skin and, in doing so, change the amount of heat they absorb, thus controlling their body temperature. Underneath the top layer of epidermis is the dermis, which contains the poison and mucous glands. The mucous glands serve to keep the skin moist and permeable for the exchange of gases and water. The poison is for protection from predators. These glands are unique to integumentary systems in amphibians.

6. Human’s Integument The human’s integument is very similar to that of most mammals. The skin in human contains sweat glands, sebaceous glands (oil), hair follicles, and nails. Sebaceous glands are found all over the body, but mostly on the scalp and face. Sweat glands are situated in small pits under the surface of the skin. A human layer of skin consists of the epidermis and underneath that, the corium, or vascular connective tissue. On the outer layer of the epidermis, keratin can be found. It is a hard and non-vascular substance that is found in largest amounts on the feet. The main purpose of the epidermis is to protect from injury what is underneath, like the nerves and vessels. New cells are always being created and destroyed on this layer. The corium, or “true skin”, as it is sometimes called, is tough and flexible. It contains the nerves and blood cells. There are two layers to the corium – the papillary and the reticular layer. The papillary contains many conical ridges, which can be seen on hands and fingers as finger prints. Underneath this is the reticular layer, made up of fibres that hold the blood vessels.

7. The End Sources http://www.britannica.com/EBchecked/topic/289723/integument/33038/Spon ges#ref=ref248939 http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookINTEGUSYS.html http://www.suite101.com/article.cfm/our_beautiful_bodies/87228 http://www.backyardnature.net/earthwrm.htm http://www.suite101.com/article.cfm/our_beautiful_bodies/84982 http://www.uoguelph.ca/zoology/devobio/210labs/ecto5.html http://www.theodora.com/anatomy/the_common_integument.html