Test 1 Prep Flashcards
Functions of integumentary system (6)
- regulates body temp
- stores blood
- protects from external environment
- detects cutaneous sensations
- excretes and absorbs substances
- synthesizes vit D
Thinnest and thickest skin?
thinnest is the eyelids- .5 mm to thickest on the heels .40
2 main parts of the skin?
superficial, thinner portion, composed of epithelial tissue is the epidermis, it is avascular
the thicker, deeper CT portion is the dermis
What are lamellated corpuscles? (also called pacinian corpuscles?
Located in subcutaneous layer, they are nerve endings that are sensitive to touch and pressure
What is the subcutaneous layer?
also called hypodermis, it is areolar/ adipose, loose CT that attaches the skin to the underlying tissues and organs
What are the cells in the epidermis?
Keratinocytes
Melanocytes
Langerhans Cell
Merkel Cells
What is the epidermis composed of?
stratified, keratinized, squamous epithelium
What do keratinocytes do?
90% of epidermal cells. They create keratin (protein)- tough fibrous protein that helps protect the skin and underlying tissues from abrasions, heat, microbes and chemicals. Keratinocytes also produces lamellar granules, which release a water repellant sealant that decreases water loss
What do melanocytes do?
8 % of epidermal cells. Develop from the ecoderm and produce melanin- contributes to skin colour. Melanin helps to absorb UV rays and protect the nucleus of Keratinocytes. Creates Vit D, blocks UV rays
What are Langerhans (or Intraepidermal macrophages)
Arise from RBM and migrate to the epidermis. They participate in immune responses mounted against microbes that invade the skin. Easily damaged by UVs. Help other cells recognize invading microbes
What are Merkel Cells (Tactile Epithelial Cells)`
Sensory Receptor
Located in deep layer of epidermis, they contact the flattened process of a sensory neuron (a merkel disc)
They detect touch
How many layers in thick skin?
5
How Many layers in thin skin?
4
Layers of the skin?
Stratum Basale or stratum germinativium- always on the bottom (deepest). Continuous cell division
Stratum Spinosum- keratinocytes arranged in 8-10 layers.
Stratum Granulosum- 3-5 layers of flattened keratinocytes. Has lamellar granules that act as water repellant. This layer is where keratinocytes undergo apoptosis (programmed death)
Stratum Lucidum- only on thick skin. 4-6 layers of clear, dead keratinocytes
Stratum Corneum- 25-30 layers, always outermost, consists of dead keratinocytes, thick cell remnants or “bags of turtle wax”
What is psoriarsis?
chronic skin disorder in which keratinocytes divide and more more quickly than normal off the stratum basale to the stratum corneum. They are shed prematurely. immature keratinocytes make an abnormal keratin, which forms flaky, slivery scales.
