Integumentary System Flashcards
Functions of the skin
- thermoregulation
- blood reservoir
- protection
- cutaneous sensations
- excretion and absorption
- synthesis of vitamin D
Types of barriers
chemical
- skin secretions’ low pH retards bacteria
- sebum and defensis kill bacteria
- melanin defends against UV damage
physical
- flat, dead cells of stratum corneum w/ lipid
- keratin and glycolipids = water proof
- drugs, drug agents, heavy metal salts, organic solvents, plant oleoresins, and lipid solubles have limited access
biological
- dendritic cells bring stuff to WBCs
- macrophages bring stuff to WBCs
- DNA electrons absorb UV radiation and convert it to heat
How much water does a person loose in a day? What is this kind of sweat called
- 500 ml
- insensible perspiration
How does the body respond to high or low temperatures?
High: dermal vessels dilate and sweat gland activity increases
Low: Dermal vessels constrict and skin temp drops to slow passive heat loss
Explain cutaneous sensations
- cutaneous sensory receptors
- detect temp, touch, pain, etc…
- deepness of receptor determines deepness of sensation
- deep ones sense pressure
Metabolic functions
- Synthesis of Vit D precursor and collagenase
- chem. conversion of carcinogens and activation of some hormones
Blood reservoir
- up to 5% of body’s blood in skin
- used to raise blood pressure when needed
- that’s why you go pale before fainting
Excretion
nitrogenous waste and salt
Dimensions of skin
area = 2 m^2 = 22 ft^2 weight = 4.5-5.5 kg = 10-11 lbs thickness = 0.5-4 mm
2 types of skin
thin/ hairy skin
- covers almost all of body
- contains hair follicles
thick/hairless skin
-palms and soles of hands, feet, and digits
3 layers of skin
Epidermis
-keratinized, stratified, squamous epithelium
Dermis
-areolar and dense irregular connective tissue
Subcutaneous/hypodermis layer
- attaches skin to underlying connective tissue
- not part of cutaneous membrane
4 types of cells in epidermis
- Keratinocytes
- 90% of epidermal cells
- produce keratin = tough fibrous protein that provides protection - Melanocytes
- produce melanin for UV protection - Langerhans cells (dendritic)
- involved in immune response
- arise from bone marrow - Merkel cells
- function in the sensation of touch along with adjacent tactile discs
Stratum Basale
- firmly attached to dermis
- single row of mitotically dividing, stem cells
- takes 25-45 days for cell to reach top
- Layer is aka as stratum germinativum
- 10-25% of layer is melanocytes
Stratum Spinosum
- “prickly layer”
- several cell layers thick
- cells have web-like system of intermediate prekeratin filaments attached to desmosomes
- keratinocytes look spikey
- lots of melanosomes and dendritic cells
Stratum Granulosum
- 4-6 cells thick (cells are flat though)
- organelles disintigrate
- keratination begins (cells accumulate keratohyaline granules which help form the fibers)
- cells accumulate lamellar granules = water resistant glycolipid
- Cells above this layer die
Stratum lucidum
- only in thick skin
- thin, clear band of 2-3 rows of flat, dead keratinocytes
Stratum Corneum
- 20-30 rows of flat, anucleated, keratinized, dead cells
- 3/4 epidermal thickness
- cells protects deeper cells, prevent water loss, and act as barrier
Outer dermal layer
- areolar ct
- dermal papillae
- cappilary loops
- corpuscles of touch
- free nerve endings
Deeper dermal layer
- dense irregular ct
- adipose cells
- heir follicles
- nerves
- sebaceous glands
- sudiferous glands
3 sensory structures in the deep dermal layer
- lamellated (pucinian) corpuscles
- deep pressure, high frequency vibrations - bulbous (ruffini) corpuscles
- deep pressure and skin distortion - Root hair plexus
- light touch
Striae
- stretch marks
- appear if skin is stretched too much and the dermis breaks