BIO 357 Lecture Notes - Lecture 5: Integumentary System, Nappy Roots, Neural Crest
Document Summary
The integumentary system contains the skin and other accessory structures associated with it. Participates in respiration (in some species more than others) Allows for glandular secretions to the outside of the body. The beginning of the modern skin can be found in the amphioxus, but it is more differentiated in vertebrates. There are two main layers to the skin. Example: fish scales are in the dermis and are covered by the epidermis. There are glands in the epidermis that give fish their slimy coating. Fish that don"t have bony scales have similar layers still. Keratin is made as underlying cells multiply and push out. Once at the top, the cytoplasm has been entirely replaced by keratin and the cells are dead. Bottom is the stratum germinativum (think germinate . The dead top layer is used for protection. The dermis contains mucus glands that secretes mucus to the surface, preventing water loss and providing extra protection to the skin.
