Integumentary System Flashcards
Integumentary system
Interface between the body and its external environment
Skin proper and its derivatives
Skin proper
2 main layers of the skin
Epidermis and dermis
Skin derivatives or appendages
Hair and nails
Sweat, sebaceous, and mammary glands
Epidermis
Upper layer of skin
Visible
Renewable population of keratinized stratified squamous cells
Made up of layers
Dermis
Lower layer of the skin
Dense regular and irregular fibrous CT containing sensory and motor nerve fibers
Consists of a papillary layer and a reticular layer
Hypodermis
Layer of white adipose and CT fibers underneath the dermis
Separates the skin proper from underlying muscle
NOT part of the skin
What are the layers of the epidermis?
- Stratum basale/germinativum
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum
Stratum basale/germinativum
Basal layer of epidermis
Gives rise to new cells at a constant rate
Some cells contain melanin
New cells move up as they differentiate
Stratum spinosum
Layer of epidermis above stratum basale
Cells have “spines” that come in contact with spines of other cells to form desmosomes called node of Bizzozero
Cells are keratinocytes
Cells and nuclei flatten as they move up from below
Stratum granulosum
Thin layer of epidermis above stratum spinosum
Cells are further differentiated
Cells have large granules called keratohyaline granules
Stratum lucidum
Thin layer of epidermis above stratum granulosum
Only found in thick skin
Cells are filled with aggregated keratin (clear appearance of cells)
Nuclei and organelles are broken down
Slowly dying cells due to lack of blood supply from the dermis
Stratum corneum
Uppermost layer of epidermis
Sloughs away
Renewed by cells coming up from the bottom layer
Keratohyaline granules
Large granules filled with the protein flaggrin that induces clumping of keratin
Increases waterproofing
Allowed evolution of aquatic to terrestrial animals
Found in keratinocytes of stratum granulosum
Melanocytes
Melanin-producing cells found in the epidermis
Derived from neural crest cells that broke off the neural tube and migrated to the skin
Melanin
Antioxidant with protective function
Protects against extreme temperature and chemical exposure; UV light radiation in the skin
2 types: eumelanin and pheomelanin
Eumelanin
Form of melanin
Brown
Most common form
Pheomelanin
Form of melanin
Red
Produced by some red-haired people
Not as common
Melanosome
Membrane-bound vesicle containing melanin
Found in melanocytes
How is melanin transferred to keratinocytes?
Keratinocytes phagocytize part of the melanocyte containing melanosomes, called cytokrine secretion
Melanocyte does not die
Langerhans cell
Stellate, APC found in the epidermis
Very active when skin is infected/exposed to infectious agents
Immunologically involved
Merkel’s cells
Cells found in the epidermis
Function is debated; may have something to do with mechanoreception
Dermatoglyphics
Genetically controlled pattern of the skin consisting of epidermal and dermal papillae
Unique to each person
Fingerprints
Papillary layer of the dermis
Upper layer, underneath the stratum basal of epidermis
Contains Meissners corpuscles
Reticular layer of the dermis
Lower layer of dermis, above the hypodermis
Contains Pacinian corpuscles
