The Integumentary System Flashcards
Integument
One of the largest and most extensive organs in the body. Composed of all four tissues, covers and protects.
Integumentary system
Includes the skin, horns, hooves, claws, glands, and hair
Keratin
A fibrous protein forming the main structural constituent of hair, feathers, hoofs, claws, horns, etc.
Keratinization
Cells expire and in doing so form the vital protective barrier that helps enable an animal’s survival
Vitamin D
A group of fat-soluble secosteroids that play a crucial role in increasing the absorption of calcium, magnesium, and phosphate
Epidermis
Composed of keratinized stratified squamous epithelium and forms an outer waterproof shield, avascular (first layer of skin)
Dermis
Majority of skin, tough leathery layer made of dense fibroelastic connective tissue, vascular (second layer of skin)
Dermal papillae
The downwards folds of the epidermis interdigitate with the upward projections of the dermis, help cement the epidermis and the dermis together
Hypodermis or subcutaneous layer
A third layer of skin found below the dermis and is composed primarily of adipose tissue
Skin covered with fur usually consists of only three epidermal layers
Stratum basale, stratum spinosum, and stratum corneum
The stratum granulosum and stratum lucidum
Found in mammals without fur and are generally missing in the skin of furred animals
The implantation angle
Clusters of hair emerge from beneath scales and are directed away from the opening at an angle, tends to be low in smooth-coated animals and typically higher in longer-haired animals
Tactile elevations
Interspersed throughout the surface of the epidermis are knoblike elevations
Tylotrich hairs
When slightly moved, or brushed lightly against objects, the tactile elevation perceives the discrete movement and alerts the animal to the presence of a close object
Vibrissae
whiskers
Principle cells found in the epidermis
Keratinocytes (majority), melanocytes, merkel cells, and langerhans cells
Keratinocytes
Produces a tough, fibrous, waterproof protein called keratin that gives skin its resiliency and strength
Melanocyte
Produces pigment found in skin, found in the deepest epidermal layers
Melanin
A dark pigment stored in membrane-bound granules called melanosomes
Melanosomes
Transported to the tips of the cellular projections, where they are released into the intracellular space and ultimately absorbed by keratinocytes
Langerhans cell
A macrophage specific to the epidermis, originates in bone marrow and subsequently migrates to the skin, where it phagocytizes microinvaders and plays an important role in helping stimulate other aspects of the immune system
Merkel cells
Can be found in small numbers at the epidermal-dermal junction, where their half-dome shape partners with a half-domed sensory nerve ending
Merkel disc
Thought to aid in the sensation of touch
Squamous cell carcinoma
Deadly form of skin cancer, spreads rapidly to local lymph nodes and is aggressively invasive locally