1. The Infamous Integumentary System
An insight to your skin, hair, nail, and glands.

2. Fast Facts & Functions Largest organ in body
Most visible organ of the body
Skin
Hair
Nails
Glands
Protection
Maintain body temperature
Stores nutrients (fat)
Senses (touch, pain…)
Excretion (of salts and water)
Secretion (oil, waste, milk)
Glands: sweat and sebaceous
Protection of tissues and organs underneath; from impact, chemicals, and infections

3. The layers and parts Epidermis Dermis Subcutaneous layers
Accessory structures
Epidermis: stems cells attached to basement membrane; projections from underlying CT feed the epidermis; melanocytes are located in the bottom part of epidermis (brown-yellow, brown, and black pigment); these cells respond to sunlight; color “bubbles up; another pigment, carotene, also determines skin color, as well as dermal circulation (dilation of blood vessels)
Dermis: papillary layer is made of LCT and has capillaries; Reticular layer is made of dence, irregular CT
Subcutaneous layer: made of LCT and fat cells; some fibers from here attach to dermis
Accessory structure: hair, sebaceous glands, sweat glands, and nails

4. The outer, epidermis, layer
Stratified squamous epithelia
This epithelia is divided into 5 layers:
Stratum germinativum
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
Normally takes 2-4 weeks for cells to move from the bottom to the top
SG: deepest layer attached to bm; stem cells and melanocytes lie here
SS: very thick layers of cells, connected by desomozone, cells dividing
SGr: cells stop dividing; cytoplasm from the dying cells start to make proteins and enyzmes
SL: cells are flattened and packed well; enzymes create the protein, Keratin; cells shed or are washed away
SC: superficial layer of dead epithelia cells and lots of keratin
Psoriasis: cells divided very fast so epidermal layer sis replaces every week instead of every 2-4 weeks

5. The middle and inner The middle: Dermis Papillary layer
Reticular layer
The inner: Subcutaneous Layer
Connective tissue fibers
Loose connective tissues and fat cells
Papillary: made of LCT, contains capillaries and nerves, nourished epidermi
Reticular: mesh of DCT that supports and provides some flexibility
Subcutaneous: children have a layer of body fat all over; this diminishes with growth and changes depending on sex (men: back, neck, upper arms, women: buttocks , hip, breasts); both can get “potbellies”

6. The Accessory Organs Hair Sebaceous glands Sweat glands Nails
Originate in dermis and subcutaneous layer
Keratinization occurs
Arrector pili: goose bumps
Sebaceous glands
Oil, waxy substance, fats = sebum
Sweat glands
Discharge sticky substance; it smells when bacteria breaks it down
Release sweat to cool body
Nails
Made of many dead keratin cells
Hair: shaft from skin in dead, keratinized cells; color determined by melanocytes (turns grey as these cells make less melanin)
Sebaceous glands: arrector pili muscles contract, squeezing waxy stuff onto skin surface; acne can occur with large sebaceous glands that become blocked, allowing bacteria to infect
Sweat glands: bacteria break down, making smell; different type of sweat glands (over 3 mill) use their secretions to cool the body
Nails: underlying blood vessels give nail pink color

7. The Epidermis

8. The sebaceous gland

9. Thick skin melanin