Integumentary System Flashcards
Integumentary system
The skin and its accessory structures; hair, nails, cutaneous glands
Job of the Integumentary System
COVER AND PROTECT
Some absorptive and secretory functions
Keeps person hydrated
Vitamin D synthesis
Sensation
Non-verbal communication
Thermoregulation
2 types of skin
- Thin - majority of skin
- Thick - palms of hands and soles of feet; 1 additional layer in epidermis provides additional protection against friction and deeper papillae to improve grip in slippery conditions
2 layers of skin
Epidermis and dermis
Epidermis
Very top layer of the skin
4/5 layers- Come/ Let’s/ Get Sun Burnt
COME - Stratum Corneum
Most superficial layer; 8-10 layers of DEAD skin cells (bags of keratin); protective and expendable; can take wear and tear of daily life
LET’S - Stratum Lucidum
Only found in thick skin; has added component eleidin = reflects light, lighter on hands and feet
GET - Stratum Granulosum
3-5 layers of deep, grainy-looking cells; due to pockets (granules) of keratin
SUN - Stratum Spinosum
Largest layer of the epidermis; contains many cellular junctions which leads to a spiny appearance under the microscope
BURNT - Stratum Basale
“Base” layer; one cell layer thick, simple cuboidal; make more epidermal cells, mitosis happens here
Skin cell journey
Basale (base) -> spinosum -> granulosum (cells mature here) -> cells die -> corneum
Cell types of the epidermis
Keratinocytes
Langerhan’s cell
Merkel’s cell
Melanocytes
Stem cells
Keratinocytes
Make keratin; 90% of cells in epidermis
Langerhan’s (dendritic) cell
Looks like a star fish; macrophages (big eater); front line of immune system
Ameboid crawling around patrolling for something foreign; if found = engulfs the foreign body via starfish arms and wear as armor to alert the rest of the immune system (antigen presenting cell)
Merkel’s (tactile) cell
Stationary and is in association with a nerve ending; sensory mechanism
Melanocytes
Makes melanin (protein); brown/black in color and near the basale layer; protects the cell DNA from UV rays -> uses melanin like an umbrella to protect the cell nucleus
Stem cells
Integumentary stem cells; located in the basale layer; produce new cells to travel upward
Dermis - 3 tissue types
Dense irregular CT
Loose areolar CT
Adipose CT
Dermis - Papillary Layer
Contain finger-like projections (superficial); loose areolar CT and fibrocytes; makes up 20% of dermis
Dermis - Reticular Layer
Dense irregular CT found here; makes up 80% of the dermis; heavy on the collagen, thus it can withstand pulling
Features of the dermis
Pacinian corpuscles and meissners corpuscles (sensory cells that detect pressure and vibration sensations)
Thermal receptors
Free nerve endings
Sebaceous glands originate here (oil)
Erector pilli muscle
Adipose tissue
Highly vasuclarized
Erector pilli muscles
Erects the hair (pillus) when it is called for; goosebumps (cold and trying to stay warm by trapping pockets of air); fear (defensive function; cats)
Friction ridges
Found in thick skin only; source of fingerprints; created by papillary extensions on top of dermal ridges; pruning when wet provides a better grip
Hair
A strand of dead keratinized cells
Hair texture and color is determined by the shape of the hair shaft; genetically determined via incomplete dominance
Hair color determined by phaomelanin (reddish brown) and eumelanin (brown/black); lack of both = blonde
Sebaceous glands
produce an oily substance (sebum); secreted to keep the skin moisturized and protected; associated often with hair follicles
Suderiferous glands - 2 types
Both associated with watery substance - sweat
Merocrine: releases at pore directly to skin surface; found all over the body; helps with temp regulation
Apocrine: associated with hair follicles; in axillary and anogenital areas (scent glands); active at puberty and onward
Ceruminous glands
Glands of the ear canal that produce wax
Cholesterol
Stabilizes the permeability of the membrane; integral for vitamin D synthesis
UV in skin -> cholecalciferol (kidneys and liver) -> calciferol (active vit D)
