There are five organs in the integumentary system. They are the hair, nails, skin, sebaceous glands, and sudoriferous glands.
The skin is the largest organ in the human body and accounts for about 15% of your total body weight. The skin is made of three main layers, the epidermis, the dermis, and subcutaneous tissue.
The epidermis is a thin outer layer and is made up of many small layers. One of them is called the basale stratum and is the only one that can complete a process called cell division. Cell division is when a already existing cell divides into two new cells. The skin is always shedding dead cells so it's important to always have new cells. The epidermis also contains a pigment called melanin, which gives skin its colour. African Americans contain more melanin in their skin than Caucasians. People with a disorder call Albinism contain very little to none melanin in their skin giving them almost pure white skin and very light blond hair. The epidermis is non-vascular meaning it doesn't contain any blood vessels. There are many different types of cells within the epidermis.
Squamous Cells- A squamous cell is one type of a epithelial cell that covers almost everywhere. They are flat and scaly and are on the surface of the skin.
Melanocytes- Produce melanin which is the pigment that gives skin its color.
Langerhans Cells- Are created in bone marrow and move into the epidermis and help protect the body against infection.
The dermis is the thicker inner layer of the skin. It contains blood vessels, connective tissue, nerves, receptors, sebaceous and sudoriferous glands, hair shafts and lymph vessels. There are two main layers of the dermis, the upper papillary layer and the lower reticular layer. The upper papillary layer consist of ridges that cause finger prints, and receptors that sense heat, pain, pressure, cold, and touch. These communicate with the central nervous system so that you can react to these feelings. Your fingertips and your lips are more sensitive than other parts of your body because there are more receptors in these parts. The reticular layer is made of connective tissue and contains, hair follicles, certain glands and nerves.
The subcutaneous tissue is the lowest layer and is made mostly of fat and stores nutrients.
The sebaceous gland is a very small gland that can only be seen under a microscope. You can find it anywhere on your skin, but mainly where it's hairy. It connects to the hair follicle on top of the skin and also helps protect the skin. It stops any foreign objects from entering through a hair follicle. The sebaceous gland also produces an oily secretion on hairs called sebum. Sebum lubricates the hair and allows it to stay healthy and shiny, but when large quantities of sebum are created, it protects the skin and hair from water by reducing the growth of microorganisms. Sebum prevents skin from cracking, turning dry, and brittle. The main function of the sebaceous gland is to protect the skin.
The sudoriferous gland is a scientific word for sweat gland. They have a small tubular structure in and under the skin. It's located in the subcutaneous tissue and under the dermis layer(skin). There are tiny openings in your skin that allow the sweat to come up. One of its functions is to produce sweat to regulate your body temperature. Sweat glands (sudoriferous glands) collect water and waste in your bloodstream and discharge or expel it through the epidermis pores. There are 2 types of sudoriferous glands, the eccrine and apocrine gland. The eccrine sudoriferous gland is spread across your entire body. The apocrine sudoriferous gland is found in the armpit and other areas.The glands produce mainly water and a variety of salts. Their main function is to regulate the temperature of your body. They also cause odour in sweat because of bacteria. Sweat produced from the glands, generally contain mostly fatty materials.
Nails are created when epidermal tissues hardens because of a protein called keratin.
Hair is an altered type of skin that grows everywhere on your body except on your lips, eyelids, palms of your hands, and the soles of your feet. Although, it grows faster in the summer and during the day, then at night in the winter. Hair grows from follicles that are hair shafts and roots of your hair. The base of your hair root is known as the hair bulb, which is where nutrients are received and new cells are formed. Follicles are found in the dermis. There are also tiny muscles that are attached to hair follicles and in certain occasions tighten together to form "goose pimples" or " goose bumps" and make the hair stand up straight. Hair contains 3 coverings: outer layer is overlapping keratin scales (cuticle), center layer is keratinized protein fiber (cortex) and generally a central core of round cells (medulla). Medulla is usually found in coarse hair, but not likely in natural blonde hair and fine hair.
Integumentary System >