Integumentary System Flashcards
What is the integumentary system?
the skin and the accessory structures
What does the integumentary system do?
protects, regulates temperature, senses things, begins the synthesis of Vitamin D
What are the three layers of skin?
epidermis, dermis, hypodermis (subcutaneous layer)
What are general traits of the epidermis?
made of stratified squamous epithelium; completely avascular (no blood vessels); thin areas can be 0.1 mm thick, thickest skin can be 1.5 mm; contains very few nerve endings;broken into five layers; 95% of the cells are keratinocytes
Five layers of epidermis
stratum corneum; stratum lucidum; stratum granulosum; stratum spinosum, stratum basale
What is stratum corneum?
dead, flat keratinocytes completely wrapped in keratin
What is stratum lucidum?
dead and flattened keratinocytes that give an extra layer
What is stratum granulosum?
keratinocytes expel liquids to form a barrier
What is stratum spinosum?
keratinocytes connect to one another with desmosomes; cells start to differentiate, and they cannot divide anymore
What is stratum basale?
keratinocyte-making stem cells and other cells are here; this is where the keratinocytes from the other layers were “born”, and they gradually pushed outwards; only found in thickest parts of skin
What are desmosomes?
specialized structures that use multiple different adhesion proteins to hold cells together and minimize the space between cells
What three cell types does stratum basale have?
Melanocytes, Merkel Cells, Langerhans cells
What are melanocytes?
produce black pigment called melanin. they produce more melanin in response to sunlight exposure. package small amounts of pigment in organelles called melanosomes. melanin absorbs UV rays from sunlight
What is skin color a factor of, and what is it NOT determined by?
it’s a factor of the number of melanosomes in the skin, and it’s not determined by the number of melanocytes
What does melanocytes generally have in their structure?
dendrites; the long projections reach into more superficial layers
What are Merkel cells?
a type of mechanoreceptor, and they sense any outside movement, and convey the message to the nerves; only mechanoreceptor in the epidermis. they are the best at detecting light pressure, as well as texture and edges of shapes; most densely found in fingertips
What do Merkel cells sit on top of?
sensory neurons; pass info to these neurons, and they’re carries to be processed
What are Langerhans cells?
a type of dendritic cell unique to the skin. dendritic cells are a type of antigen-presenting phagocyte, which are a type of white blood cell. Langerhans cells are considered the first line of defense for the immune system. Should an invader enter the immune system, the Langerhans cells will basically destroy it
What is the dermis?
the dermis is under the epidermis, and it is also thicker than the epidermis. it has vasculature. the dermis and epidermis just kind of “cross” into each other, and the dermis protrudes into the epidermis to give nutrients. the protrusions are called dermal papillae, and they are responsible for unique fingerprints
What are the 2 types of glands in the dermis?
Sebaceous glands and sweat glands
What are sebaceous glands?
glands that are responsible for producing and secreting an oil called sebum. typically found attached to hair follicles
What are the two types of sweat glands?
eccrine and apocrine
What are eccrine glands?
sweat glands that simply release water to cool down the body’s temperature. usually release their liquid directly onto the skin
What are apocrine glands?
a special sweat gland located in the armpits and groin area. they release extra oil into their secreted fluid. responsible for smelly compounds, or natural musk. usually release their secretions into a hair follicle
