Chapter 6 - The Integumentary System Flashcards
True or false: Inspection of the skin, hair, and nails is significant part of a physical exam
True
True or false: Skin is NOT the most vulnerable organ
False; skin is the most vulnerable organ. It’s exposed to radiation, trauma, infection, and injurious chemicals
True or false: the skin receives more medical treatment than any other organ system
True
Define dermatology
The scientific study and medical treatment of the integumentary system
What are the six main functions of the skin?
1) Resistance to trauma and infection: Keratin; dermacidin & defensins; acid mantle 2) Other barrier functions: Water (protects against dehydration) UV radiation; melanin Harmful chemicals 3) Vitamin D synthesis: Skin carries out first step; Liver & kidneys complete process 4) Sensation receptors Touch, temperature, pressure, vibration, tickle, itch, and pain sensations 5) Regulation of body temperature Thermoreceptors Vasoconstriction/vasodilation If you are too warm, do cutaneous blood vessels vasodilate or vasoconstrict? Perspiration 6) Nonverbal communication
What are the two layers of the skin (cutaneous membrane)?
Dermis and epidermis
What are the two main parts of the skin?
The cutaneous membrane (the skin) and the subcutaneous layer
What type of cells is the epidermis made of?
Keratinized stratified squamous epithelium
Describe the characteristics of the epidermis
Includes dead cells at skin surface packed with tough keratin protein
5 distinct strata (layers) in thick skin; 4 strata in thin skin
Lacks blood vessels
Depends on the diffusion of nutrients from underlying connective tissue
Contains sparse nerve endings for touch and pain
List the five epidermal cell types
Stem cells, keratinocytes, melanocytes, tactile (merkel) cells, and dendritic cells
Describe stem cells in the epidermis
Undifferentiated cells that give rise to keratinocytes
In deepest layer of epidermis (stratum basale)
Describe keratinocytes
The majority of epidermal cells; Synthesize keratin
Describe melanocytes
Synthesize pigment melanin (shields DNA from UV radiation)
Occur only in stratum basale but have branched processes that distribute melanin to keratinocytes
Describe tactile (merkel) cells
Touch receptor cells in basal layer
Describe dendritic cells
Macrophages (WBCs) that are part of the immune system
Found mainly in stratum spinosum and granulosum
Describe thick skin and where it’s found
Lacks hair follicles and sebaceous (oil) glands
Has stratum lucidum
Generally has more sweat and sensory receptors
Epidermis 0.5 mm thick
Found on palms of hands and soles of feet
Describe thin skin
Possesses hair follicles, sebaceous glands, and sweat glands
Epidermis about 0.1 mm thick
Name the layers of the epidermis from deepest to shallowest
Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
Describe the stratum basale
Single layer of stem cells and keratinocytes
Stem cells divide and give rise to keratinocytes that migrate toward skin surface to replace lost cells
Also contains a few melanocytes and tactile cells
Deepest epidermal layer
Describe the stratum spinosum
Several layers of keratinocytes joined together by desmosomes and tight junctions
Named for appearance of cells after histological preparation (spiny)
Also contains some dendritic cells
Describe the stratum granulosum
Three to five layers of flat keratinocytes
Cells contain dark-staining kerotohyalin granules
Describe the stratum lucidum
Thin, pale layer found only in thick skin
Describe the stratum corneum
20-30 layers of dead, scaly, keratinized cells
Resists abrasion, water loss, penetration of bacteria and chemicals
Describe the life history of a keratinocyte
Stem cells divide producing keratinocytes.
New keratinocytes push older ones toward the surface
Over time, keratinocytes flatten, produce more keratin and membrane-coating vesicles that release lipids that waterproofs the cell.