MICRO 20 Lecture Notes - Lecture 3: Merocrine, Sebaceous Gland, Pheromone
Document Summary
Epidermis superficial layer of the skin with cornfield stratified squamous epithelia. Five layers of epidermis found on palms and soles of feet. 4 layer of epidermis found everywhere except palms and soles soles. Skin stem cells that divide to produce new basal cells and new keratinocytes. Contain extensions that extend into spinosum and produces melanin deposited over nuclei in stratum basale and stratum spinosum. Macrophage immune cells that use phagocytosis (cell- eating) to remove debri and foreign, old and dead cells. Produces new cells and pushes older cells to stratum corneum. Divides at a rate that produces new skin layer ever two weeks that slows with age and chemotherapy. Keratinocytes make up the stratified squamous of epidermis. All keratinocytes in this layer start to die because they are from from blood vessels in dermis. They dehydrate an flatten out with only keratinocytes being left inside.
