Chapter 5 - The Integumentary System Flashcards
Epidermis
Superficial surface coat. Avascular. Made up of layers of epithelial cells and made to protect the body.
Dermis
Stong, flexible connective tissue. It has nerve fibers, macrophages, WBCs, and blood vessels. It has cutaneous receptors, glands, and hair follicles.
Hypodermis
Deepest region. It anchors the skin to organs. It has insulation, mostly adipose tissue. Acts as a shock absorber and contains nerves.
Keratinocytes
Produce keratin, a protein that waterproofs and hardens the skin. The most numerous cell type
Melanocytes
In the lower epidermis. Produce the pigment melanin
Merkel’s cells
Sensory cells, they have cell receptors. Are associated with nerve endings. Found deep in the epidermis.
Langerhan’s cells
Dendritic cell. Macrophage that helps activate the immune system
5 layers of the epidermis
Stratum Basale Stratum Spinosum Stratum Granulosum Stratum Lucidum Stratum Corneum
Stratum Basale
Deepest layer. attached to the dermis, it rests on the basement membrane. Usually a single layer of stem cells. There is rapid division of cells there and melanocytes synthesize melanin there which protects the cells from UV radiation.
Stratum Spinosum
About 8- 10 rows of cells. Has prekeratin filaments, flat spine-like projections bound together by desmosomes. Contains melanin and Langerhan’s cells, that protect against bacteria and cancer cells.
Stratum Granulosum
Granular, thinner layer 3-5 rows. Where keratinization begins. Cells make keratin and keratohyalin.
Stratum Lucidum
Clear layer, very thin, only appears in thick epidermis (soles of feet, palms of hands). Made up of a few rows of flat, dead keratinocytes.
Stratum Corneum
Outermost layer of dead flat cells. Accounts for about 3/4 of the thickness of the epidermis. 20-30 rows of cells, constantly being shed. There to waterproof and act as a barrier against physical, chemical, and biological factors.
2 dermal layers
Papillary
Reticular
Papillary
Consists of areolar connective tissue with collagen and elastic fibers. It has blood vessels, and nerve endings and Meissner’s corpuscles. Dermal papillae are the superior surface protruding into the epidermis forming patterns called fingerprints.
Reticular
About 80% of the thickness of the dermis. Made of dense connective tissue. The less dense regions form lines, lines of cleavage, which surgeons try to follow.
Melanin
It runs yellow, to brown, to black. Produced by melanocytes, the more melanin, the darker the color. Tyrosine, an amino acid, is very prominent in melanin.
Carotene
Runs from yellow to orange. Found mainly in the stratum corneum, and the adipose tissue of the hypodermis. Most obvious in the palms of hands and soles of feet.
Hemoglobin
Pinkish hue, due to the oxygenation of the blood.
Hair Functions
Alerts body to the presence of insects. Guards scalp against physical trauma, heat loss, and sunlight.
Hair Shaft
Protrudes above the skin.
Hair Root
Has three layers:
1) The central core, the medulla
2) The cortex, outer layer made of hard keratin
3) Cuticle, has the most hard keratin.
Hair Color
Determined by the amount and kind of melanin.
Hair Folicle
Extends into the dermis, sometimes the hypodermis. The outer part is connective tissue, and the inner part is epithilial root sheath. Has nerve endings, sebaceous glands, and smooth muscle structures. Has matrix cells that form the hair.
