Chapter 6: The Integumentary System Flashcards
What is the Integumentary System?
A fancy name for the SKIN; It consists of the skin and accessory organs such as hair, nails and cutaneous glands
Why is the skin the most vulnerable organ?
B/c it is exposed to radiation, trauma, infection and injurious chemicals
What are the Three Layers of Skin?
1) Epidermis
- stratified squamous epithelium
2) Dermis
- Deeper connective tissue layer
3) Hypodermis
- connective tissue layer below dermis (not part of skin, but associated with it
What is Thick Skin?
- Type of Skin that covers the front of hands, bottoms of feet
- Has sweat glands, but no hair follicles or sebaceous (oil) glands
- The epidermis is 0.5mm thick
- contains five strata
What is Thin Skin?
- Type of Skin that covers most of the body
- Has hair follicles, sebaceous (oil), and sweat glands
- The epidermis is about 0.1mm thick
- Contains four strata
What are some functions of the Skin?
- Resistance to trauma and infection, (Keratin, Dermacidin and defensins, Acid Mantle)
- It is the our first line of defense and barrier from water, UV radiation and harmful chemicals
- Helps with Vitamin D synthesis (first step)
- Sensation (receptors for temperature, touch, pain ect.)
- Thermorgulation (Perspiration)
- Nonverbal communication (Facial expression)
What are some characteristics of the Epidermis?
- It is keratinized stratified squamous epithelium
- dead cells at skin surface with though keratin protein
- Lacks blood vessels
- contains sparse nerve endings for touch and pain
What are the five Epidermal Cell Types?
1) Stem Cells
2) Keratinocytes cells
3) Melaocytes cells
4) Tactile cells
5) Dendritic cells
What are Stem Cells?
- Type of Epidermal cell
- Undifferentiated cells that give rise to keratinocytes
- It is in the deepes layer of the epidermis (stratum basale)
What are Keratinocytes
- Type of Epidermal Cell
- It is the majority of epidermal cells
- responsible for synthesizing keratin
What are Melanocyte cells?
- Type of Epidermal Cell
- It syntesizes pigment melanin (coloring of hair and eyes) that shields DNA from ultraviolet radiation
- Occurs only in stratum basale but have branched processes that spread among keratinocytes and distribute melanin
What are Tactile Cells?
- Type of Epidermal cell
- Has touch receptor cells associated with dermal nerve fibers
- Located in basal layer of epidermis
What are Dendritic Cells?
- Type of Epidermal cell
- Macrophages originating in bone marrow that guard against pathogens
- found in stratum spinosum and granulosum
How are Keratinocytes produced?
- They are produced by mitosis of stem cells in stratum basale or mitosis of keratinocytes in the deepest part of stratum sqinosum
What is the Stratum Basale?
- Deepest layer of the epidermis
- It is a single layer of stem cells and keratinocytes resting on the basement membrane
- stem cells divide and give rise to keratinocytes that migrate toward skin surface to replace lost cells
What is the stratum spinosum?
- Layer of the Epidermis
- It is several layers of keratinocytes joined together by desmosomes and tight junctions
- named for appearance of cells after histrological preparation
What is the Strarum Granulosum?
- layer of the epidermis
- Three to five layers of flat keratinocytes
- Cells contain dark- staining keratohyalin granules
What is the Stratum Lucidum?
- Layer of the Epidermis
- Thin, pale layer found only in Thick Skin
- Keratinocytes packed with clear protein eleidin
What is the Stratum Corneum (surface layer)
- Layer of the Epidermis
- Several layers (up to 30 layers) of dead, scaly, keratinized cells
- Resists abrasion, penetration, water loss
What are calluses/ corns?
- Thick accumulations of dead keratinocytes on hands or feet?
What are the four important events that occur in the Stratum Granulosum?
1) Keratohyalin granules release filaggrin (a protien that binds keratin into tough bundles)
2) Cells produce tough envelope proteins beneath their membranes
3) Membrane- coating vesicles release lipid mixture that spreads out and waterproofs it
4) Keratinocytes’ organelles degenerate and the cells die
What is the Epidermal Water Barrier?
- It is tught junctions between skin cells and waterproofing that occurs in the stratum granulosum
What are some functions of the Epidermal Water Barrier?
- water retention
- Helps prevent dehydration
- Does not prevent the absorption of water by stratus corneum
What are some characteristics of the Dermis?
- It is the connective tissue layer beneath epidermis
- Contains a lot of blood vessels, sweat glands, sebaceous glands and nerve endings
- Is the tissue of the facial skin to which skeletal muscles attach and cause facial expressions and emotions
- Houses hair follices and nail roots
What is the Dermal Papillae
- Type of wavy, dermal boundary that is upwards, finger-like extensions of the dermis
What is the Epidermal Ridges?
- downward waves of epidermis
