Integument
Topics Covered
Introduction to the skin
Epidermis
Dermis
Introduction
The integument, or skin is an organ system of the body made of tissues that work together as a single structure to perform unique and critical functions, such as protection from the external environment and body temperature regulation. The skin is composed of many layers of cells. It is made of two to three layers- the epidermis, and the dermis, which are made up of both epithelial tissue and different types of connective tissue. These layers are held to underlying structures by connective tissue. (Link to figure 5.2- Layers of the Skin)
The dermal layer of skin, which sits below the top layer- the epidermis- is well vascularized (has numerous blood vessels). It also has numerous sensory, and autonomic and sympathetic nerve fibers ensuring communication to and from the brain.
The hypodermis, which sits below the dermal layer, is not always considered a layer of the skin. It acts as a reserve for adipose tissue.
Epidermis
The outer layer of skin and is composed primarily of epithelial cells. It serves to primarily protect the body. The epidermis has 5 layers:
1. Stratum Corneum
2. Stratum Lucidum
3. Stratum Granulosum
4. Stratum Spinosum
5. Stratum Basale
(Linked to figure 5.5- Layers of the Epidermis)
What type of epithelium characterizes each layer? What are the characteristics that make each layer different? What are the other cell types found in the epidermis?
Dermis
The dermis is made of connective tissue that is attached to epidermis by a basement membrane. It serves to support the epidermis and connects epidermis to underlying hypodermis. The dermis contains the blood and nerve supply and the other accessory structures of the skin, like arrector pili and glands.
The dermis has 2 layers:
1. Papillary layer: adhesion to epidermis (dermal papillae)
2. Reticular layer: larger section of dermis. Primary sensory functions of skin. Nerve and blood vessels present throughout