Integumentary System Flashcards
Functions of the Skin
1) Protection
2) Thermoregulation
3) Touch
4) Vitamin D and Melanin Production
5) Stores blood
6) Absorbs and excretes
Layers of the Skin
1) Epidermis
2) Dermis
3) Hypodermis/Subcutaneous
Name Types of Epidermal Cells
1) Keratinocytes 2) Melanocytes 3) Langerhan cells 4) Merkel cells
Keratinocytes
- 90% of your skin cells
- produce the protein keratin: tough and protects
- Produce lamellar granules: make the skin waterproof
Melanocytes
- cuboidal cells with projections linking them to keratinocytes
- creates melanin (Found in skin and mucous membranes)
- 1) Pheomelanin - yellow-red
- 2) Eumelanin - brown-black
- contains melanin caps for nuclei = protects DNA from UV rays
Langerhan cells
- cells with projections among keratinocytes
- born in the bone marrow and then migrate to the epidermis when they mature
- immunity
Merkel cells
- deep cells in epidermis
- in contact with sensory neurons
- Merkel + tactile disk + neuron = sense touch
Layers of the epidermis (Top to Bottom)
1) Stratum Corneum 2) Stratum Lucidum 3) Stratum Granulosum 4) Stratum Spinosum 5) Stratum Basale
Stratum Basale
- epidermal basement (cellular division occurs)
- Cuboidal cells make new keratinocytes
- Melanocytes and Merkel cells and neurons
- Stratum germinativum (means the layer that germinates/grows) = mitosis occurs
Stratum Spinosum
- Looser and rounder cells anchored by proteins (but not a strong anchor)
- Langerhans cells - immunity
Stratum Granulosum
- Apoptosis = programmed cell death happening so the above layer can be created (they lose the nucleus when they die and become sacs of keratin)
- Flattened
- Lamellar granuoles work here(make skin waterproof)
- Form layer up above
Stratum Lucidum
- Fingertips and Palms and soles of the feet
- Dead Keratinocytes
- Contain lots of keratin
Stratum Corneum
- most prevalent in thick skin
- Scales or squames
- Contain more keratin than stratum lucidum
- Are shed constantly
FUN FACTS ABOUT THE SKIN THAT MAY OR MAY NOT BE IMPORTANT
*If you rub off too much of the stratum corneum rubs off you get a callus*
*If you rub down into the live skin cells, the stratum spinosum cells pop and release interstitial fluid and form a blister*
*Every four weeks you have a new set of skin*
The dermis contains two regions….
1) Papillary region
2) Reticular region
Papillary region
- Dermal papillae - vary in size depending on skin thickness
- Thin = fewer papillae/irregular
- Thick = numerous/regular
- Capillary loops: blood and nutrients!
- Meissner corpuscles: touch receptors = nerve endings
Reticular region
- -thick bundles of collagen in rectangular net with irregular connective tissue with fibroblast (coarse elastic fibers)