Quiz 5 Flashcards
Integumentary system
Skin
Functions of Integumentary system
- Protection
- Body temperature regulation
- Cutaneous sensations
- Metabolic functions
- Blood reservoir
- Excretion
3 types of protection barriers of skin
- Chemical (low pH secretions and anti-bacterial activity)
- Physical/mechanical barriers
- Biological barriers (dendritic cells and macrophages)
Physical/mechanical barriers of skin
- Keratin and glycolipids block most water and water-soluble substances
- Limited penetration of skin by lipid-soluble substances, plant oleoresins (e.g. poison ivy, organic solvents, etc.0
Macrophages
Eat debris formed by dead cells
Body temperature regulation of skin
- Insensible perspiration (can’t tell you’re sweating)
- Sensible perspiration
- Bloodflow restriction (cold weather= constrict bloodlfow to fingers and toes)
Cutaneous sensations of the skin
Temperature, touch, and pain
Metabolic functions of the skin
Synthesis of Vitamin D precursor and collagenase (break down collagen)
Blood reservoir of skin
Up to 5% of body’s blood volume
Excretion
Nitrogenous wastes and salt in sweat (part of excretory system)
Two major regions of skin
- Epidermis
2. Dermis
Epidermis
- top layer
- keratinized stratified squamous epithelium
Cells of epidermis
- Keratinocytes
- Melanocytes
- Epidermal dendritic (Langerhans cell)
- Tactile (Merkel) cells
Keratinocytes
majority of epidermis, produce keratin
Melanocytes
produce melanin, in stratum basale
-melanin picked up by keratinocytes
Epidermal dendritic (Langerhans cells)
resident tissue phagocytizer to activate immune system
Tactile (Merkel) cells
at dermis-epidermis junction, touch receptor
2 types of skin
- Thick skin (on palms and bottom of feet, NO HAIR)
2. Thin skin (found everywhere, has hair)
Thin skin layers
- Stratum corneum
- Stratum granulosum
- Stratum spinosum
- Stratum basale
Stratum corneum
- most superficial layer
- 20-30 layers of dead cells filled with keratin
- glycolipids in extracellular space
Stratum granulosum
- three to five layers of flattened cells
- organelles deteriorating
- cytoplasm filled of lamellated granules (release lipids) and keratohyaline granules
Stratum spinosum
- keratinocytes unified by desmosomes (spines)
- bundles of intermediate filaments-> pre-keratin
Stratum basale
- deepest epidermal layer
- one row of actively mitotic stem cells
- see occasional melanocytes and epidermal dendritic cells (makes all cells above it)
Thick skin layers
- Stratum corneum
- Stratum lucidum
- Stratum granulosum
- Stratum spinosum
- Stratum basale
Stratum lucidum
- thin, transparent band superficial to stratum granulosum
- a few rows of flat, dead keratinocytes
Dermis
- strong, flexible connective tissue
- cells include fibroblasts, macrophages, and occasionally mast cells (release histamine) and white blood cells
Two layers of dermis
- Papillary (20%)
2. Reticular (80%)
Papillary layer of dermis
- Areolar connective tissue
- Dermal papillae (hills) contain:
- Capillary loops
- Meissner’s corpuscles
- Free nerve endings
Reticular layer of dermis
- dense irregular connective tissue
- collagen fibers provide strength and resiliency
- elastin fibers provide stretch-recoil properties