The integumentary system is comprised of skin, hair, scales, feathers and nails. The integumentary system protects the body from physical damage and it is the largest organ system, mostly due to the volume of skin. Skin is composed of several layers. In skin, the top layer of skin is called the epidermis, the middle layer is called the dermis and the bottom layer is called the subcutaneous layer.
The integumentary system is a system that a lot of people aren't even aware is there? But it's right there in front of you whenever you look at somebody you're actually seeing their integumentary system. You can't see their digestive system or the nervous system but this is my integument it's the skin. Now a lot of times we think oh what does the skin do? Well its actually involved in a lot of different things. It's involved in protection obviously if I get a fungus on my skin and I just sit there and brush it off how didn't why didn't it detect my muscles? Because my skin is protecting everything underneath, it produces oils that help protect me from water loss and things like that.
It's involved in thermoregulation it can cause the hairs to erect now in humans getting a little goose bumps not so effective if you kitty cat erecting your hair, helps create a greater layer of the thermoregu- thermo protection insulation. I can blush or send a lot of blood vessels open them up in my skin and that's allow me to dump heat out or when I'm getting cold you may notice that somebody gets pale and that because they're constructing the bloods part of their skin to reduce the loss of heat to their skin. We excrete waste I mean that's a lot of what sweat is, there's all sorts of chemicals in there. It's involved in various senses; pain, heat, pressure, touch all these senses are involved in the skin.
Now there's two main layers to the skin. There's the epidermis which is the outer layer and then the dermis is underneath it there's another layer called the subdermis but that's not really part of the integumentary system.
The epidermis is the outer layer of the skin and this is the layer that everybody sits there when you do this you're scratching off epidermal cells but that's okay they're constantly undergoing cell division to replace them so the epidermis is involved in a lot of protection of the more delicate tissues that are underneath like the blood vessels and such. The epidermis doesn't actually have it's own blood vessels.
Unlike the dermis, the dermis does contain the blood vessels that has nerve endings has the sweat glands and everything else that we often think of as the important structures of the skin.
Now that subdermis that I mentioned before is again not technically part of the integumentary System but it is important layer of what we think of as the skin because this is the connective tissue that helps anchor the skin to the lower structures like your muscles and such and it's also often a layer of has layers of fat that help in thermo insulation it also helps in cushioning which specially on our rear ends helps when we sit from damaging our delicate bodies and that's the integumentary system.