Chapter 13 - Integumentary System Flashcards
What is the integumentary system?
In addition to the skin, the integumentary system includes the hair and nails, which are organs that grow out of the skin.
What are the 2 layers of the skin?
The epidermis and the dermis.
What is da epidermis?
The outer layer of skin is the epidermis. This layer is thinner than the inner layer, the dermis. The epidermis consists mainly of epithelial cells, called keratinocytes, which produce the tough, fibrous protein keratin.
What happens to the epidermis?
Cells lower on the cell divide and move up to the surface. They die before they get there and protect the cells underneath.
What is da dermis?
The dermis is the inner and thicker layer of skin. It consists mainly of tough connective tissue and is attached to the epidermis by collagen fibers. The dermis contains many structures, as shown in the figure above, including blood vessels, sweat glands, and hair follicles, which are structures where hairs originate. In addition, the dermis contains many sensory receptors, nerves, and oil glands.
What is hair? (COMPLEX)
Hair is a fiber that is found only in mammals. It consists mainly of keratin-producing keratinocytes. Each hair grows out of a follicle in the dermis. By the time the hair reaches the surface, it consists mainly of dead cells filled with keratin. Hair serves several homeostatic functions. Head hair is important in preventing heat loss from the head and protecting its skin from UV radiation. Hairs in the nose trap dust particles and microorganisms in the air and prevent them from reaching the lungs. Hair all over the body provides sensory input when objects brush against it or it sways in moving air. Eyelashes and eyebrows protect the eyes from water, dirt, and other irritants.
What are fingernails?
Fingernails and toenails consist of dead keratinocytes that are filled with keratin. The keratin makes them hard but flexible, which is important for the functions they serve. Nails prevent injury by forming protective plates over the ends of the fingers and toes. They also enhance sensation by acting as a counterforce to the sensitive fingertips when objects are handled. In addition, the fingernails can be used as tools.
What is a tan?
A sign of skin damage that appears healthy.
What are the different cells of the Epidermis?
90% keratinocytes (epithelial cells that make keratin)
8% melanocytes (produce melanin)
1% Langerhans cells (immune cells that find and fight pathogens)
<1% Merkel cells (respond to light touch and connect to nerve endings in the dermis).
What are the 5 layers of the Epidermis?
Stratum Basale
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum
Stratum Corneum
What is the stratum basale?
The deepest layer of the dermis. It contains basal cells (stem cells which make keratinocytes), Melanocytes, and Merkel cells.
What is the stratum spinosum
The layer of skin that is above the Stratum basale (going away from the body). This is the thickest of the epidermal layer.
Contained in this cell are keratinocytes, spiny cellular projections, and Langerhans cells.
Stratum Granulosum
The next layer above the stratum spinosum.
The keratinocytes in this layer become filled with keratin, and their cytosplasm takes on a granular appearance.
Those keratinocytes release lipids which make a lipid barrier in the epidermis.
Cells in this zone begin to die because they are too far from blood vessels. They eventually eat themselves and their organelles, leaving behind a keratin husk.
What is the stratum lucidum?
The net layer above the stratum lucidum. It is only found on the soles of feet or palms of hands.
This layer is mae of stacks of clear dead keratinocytes that protects the underlying layers.
What is the Stratum Corneum?
The uppermost layer of the epidermis that covers the whole body. This is a waterproof protective layer that is made of dead keratinocytes, and is shed contiually.
How long does it take for newly formed keratinocytes to make their way from the stratum basale to the top of the stratum corneum?
48 days
What are the crucial functions of the epidermis?
Protection
Water Retention
Vitamin D synthesis
What does the epidermis protect the body from?
Physical damage - Corneum blocks lots of damage.
Pathogens - Generally, pathogens can’t come through the epidermis unless it is breached. SOme factors that contribute to this is high acidity, low water, antimicrobial cells and Langerhans cells that PHAGOCYTIZE bacteria and pathogens.
UV light - Melanocytes in the stratum basale have organelles called melanosomes. As they become full of melanin, they move upwards in the skin and absorb UV radiation.
How does the Epidermis retain water?
There is a lipid barier that is organized in the stratum corneum that prevents water loss.
The skin is selectively permeable and allows for some fat-soluble substances to pass through the epidermis. This is a blessing and a curse because good and bad things can ass through the epidermis.
