Skin Basics & Prevention Flashcards
What comes from the ectoderm?
- Epidermis
- Hair
- Glands
What comes from the mesoderm?
- Dermis
What comes from the endoderm?
- Epithelial linings
- Linings of the glands
What is the baby coated with at birth?
- Vernix caseosa: a whitish paste formed by secretions from sebaceous glands and degenerated epidermal cells and hairs in order to protect the skin against the amniotic fluid
What are dermatoglyphs?
The skin ridges that fingerprints are based on that develop from 3-6 months of gestation from genetic factors and remain the same for life
What is the stratum corneum?
- Layer closest to the surface that is dead skin cells
- Looser appearance
What is the stratum lucidum?
- Several layers of flattened dead cells and is only found in thick skin
What is the stratum spinosum?
- Spine-like cytoplasmic extensions of the cells interconnect this layer giving it a “spiny” appearance
What is the stratum basale?
- Deepest layer of the epidermis
How long does renewal of the human epidermis take?
3-4 weeks
What is the most common type of skin cells?
Keratinocytes (90%)
What are melanocytes?
- migratory neural crest cells that invade the epidermis and produce melanin to protect against UV light
What are Keratinocytes?
Most common skin cell that makes keratin to provide strength to the skin, hair & nails
What is the ratio of keratinocytes to melanocytes in the stratum basale?
1 melanocytes for 5-6 keratinocytes
What are Langerhans Cells and where do you find them?
- Cells in the deeper layers of the epidermis that play a role in the immune reactions of the epidermis helping to initiate an immune response
What are merkel cells?
- Cells that provide information on light touch sensation and may be associated with sensory nerve endings as “Merkel nerve endings”
When do we begin to develop hair?
12 weeks of gestation
T or F: In a hairy area, your skin takes longer to heal
False - when there is a lot of hair, the epithelial cells migrate to the surface and help to close the wound
What are sebaceous glands?
- Make sebum: an oil lubricant, and buds from the side of a developing hair follicle
What is an apocrine gland?
A highly coiled sweat gland that pinches off and is released into the lumen and plays a role in sexual and social communication
What is eccrine sweat gland?
A solid, unbranched epithelial downgrowth that coils at the tip to form secretory portion & is attached to the epidermis
What are the layers of the dermis?
Papillary (loose) and Reticular (Dense irregular - 80%)
What are the contents of the dermis?
- collagen
- elastin
- ground substances
- fibroblasts
- macrophages
- mast cells
- leukocytes
- lymphatic glands
- blood vessels
- nerve fibers
Where are the epidermis and dermis:
a. thickest
b. thinnest
A. Epidermis thickest at palms/soles (1.5 mm) and dermis at the back (3.0 mm)
B. Epidermis thinnest at eyelids (0.05 mm) and dermis at eyelids (0.3 mm)
What are the contents of the hypodermis/subcutaneous tissue
- Adipose tissue
- Fascia
- Large nerves, blood vessels, and fibroblasts
What are the functions of the hypodermis?
- Regulate skin and body temperature
- absorb shock
- connect skin to underlying tissue
What are the functions of the skin?
- Sensation
- Prevention of fluid loss
- Immunity
- Thermoregulation
- Protection from UV Rays
- Synthesis & Storage of Vitamin D
- Aesthetic and Communication
What is the most prevalent diagnosis impacting skin sensation?
- Diabetic polyneuropathy –> leads to trauma that can be unnoticed causing wounds that are difficult to heal
What are free nerve endings?
- unencapsulated nn endings in the stratum basale that play a role in thermoregulation, nociception, and cutaneous mechanoreception
What are tactile/Merkel’sDisks
Slow-adapting, un-encapsulated nerve endings that respond to light touch
What are Meissner’s corpuscles?
Rapidly-adapting, encapsulated neurons that respond to low-frequency vibrations and touch
What is a Krause bulb?
An encapsulated nerve fiber in the middle dermal layer that detects light pressure, soft low vibrations, and cold temperatures
What are Ruffini endings?
A slow adapting, encapsulated receptor that responds to skin stretch and plays a role in warm temperatures
What is a root hair plexus?
A network of sensory fibers around the root of the hair follicles in the deep dermis that detect and transmit any hair movement
What are pacinian corpuscles?
Rapidly-adapting, deep receptors that respond to deep pressure and high frequency vibration
What is hygroscopy?
The natural moisturizing factors that attract and hold water in the stratum corneum
What are the 3 properties that contribute to the skins role in the body’s immune system?
- Langerhans cells
- Acidic pH
- Antimicrobial peptides and lipids
What happens when you get cold?
Blood flow constricts and reduces flow of blood to the skin + goosebumps
What happens when you get hot?
Blood dilates so more blood flow to the skin
What is normal skin blood flow at rest/inactive?
30-40 mL/min/100g
Where is vitamin D3 made?
In the stratum basale and stratum spinosum
What are age related epidermal changes?
- flattening of dermal-epidermal junction
- changes in basal cells
- dec. in langerhans cells
- dec. in melanocytes
- thinning
What are age-related dermal changes?
- dec. dermal thickness
- degeneration of elastin fibers
- dec. vascularization
What are age-related subcutaneous changes?
- It thins leading to a decreased ability to maintain body temperature
What are the appendage changes of aging skin?
- Dec sweat glands, specialized nerve endings, hair bulb melanocytes, hair follicles
- Sebaceous glands produce less oil
Define erosin?
Loss of superficial epidermis only
Presentation of erosin
- Lack of bleeding, increased redness of skin
- Ex: Abrasion, superficial burns
How do erosions heal?
- local inflammatory response & epidermal replacement from migrating keratinocytes
Define partial thickness skin wound?
Loss of the epidermis and part of the dermis
Presentation of partial thickness skin wound?
Bleeding
- Ex. Stage II Pressure ulcers, second degree burns, skin tears, deep abrasions
How do partial thickness wounds heal?
Re-epithelialization as a result of epithelial cell migration from wound edges, hair follicles, & sebaceous glands (7-10 days)
Define full thickness wound
Loss of epidermis and dermis, extending into the subcutaneous tissue and in some cases involving bone, tendon, or muscle
What are examples of a full thickness wound?
- Full thickness/Third degree burns
- Stage 3&4 pressure ulcers
- Sx incisions
- Traumatic wounds
- Wounds that require debridement
How do full thickness wounds heal?
Secondary intention
What are the mechanisms of cell injury?
- Ischemia
- Infections
- Immune rxns
- genetic
- nutritoinal
- physical
- mechanical
- chemical
- pyschological
What are the types of cell injury?
- Reversible: Non-lethal
- Irreversible: Apoptosis & Necrosis
What is coagulative necrosis?
Necrosis from ischemia/infarction that is firm & denser than surrounding tissue
What is caseous gangrene?
From TB or fungal infections where all cellular outline is lost and tissue appears crumbly and cheese like
What is liquefactive gangrene?
From a bacteria (Ex. Staph auerus) where the tissue becomes softened and liquefied
What is fatty necrosis?
From acute pancreatitis/abdominal trauma where the fat is broken down in the subcutaneous tissue
What is fibrinoid necrosis?
From trauma in a blood vessel wall that causes breakdown products of fibrin and collagen
What is gangrenous necrosis?
Discolored or black tissue and associated sloughing of natural tissue that can be dry or wet
What are 4 healing response mechanisms?
- Continuous cell cycling
- Cell proliferation
- Cell regeneration
- Fibroproliferative resonse/healing
What is healing by primary intention (Category 1)?
- A clean surgical incision w/no contamination and minimal tissue loss where the edges can be approximated and secured w/sutures, staples or surgical glue
What is healing by delayed primary intention (Category 2)?
Wound edges are not approximated & body has release of multiple proinflammatory cytokines, chemokines & growth factors w/foreign debris walled off by macrophages
What is healing by secondary intention (Category 3)?
An inflammatory response w/granulation tissue formation and re-epithelialization w/wound contraction by myofibroblasts
What is healing for partial thickness wounding (Category 4)?
Healing from epithelial cell mitosis and migration w/epithelial islands forming
List the stages of acute wound healing
- Hemostasis
- Inflammation
- Proliferation
- Remodeling
What is hemostasis?
- Vasoconstriction of injured vessel (to stop bleeding)
- Vasodilation of adjoining vasculature once a stable
- Stable clot formed
What happens during the inflammation stage?
- Immune response initiated
- Slough is formed (from autolytic process)
- Wound debridement (of eschar by from macrophages)
- Neo-angiogenesis: tissue formation supported
What occurs during the proliferation phase?
- Angiogenesis (new blood vessels to give nutrients and take away waste)
- Fibroplasia (Fibroblasts migrate and begin to lay down collagen I and III)
- Matrix deposition (Fills in the gaps)
- Epithelialization (Keratinocytes migrate to resurface the wound)
What occurs during remodeling?
- dermal regeneration
- wound contraction (Dec. size)
- Programmed shrinkage of granulation tissue
What two nutritional components are important for tissue healing?
Protein and Vitamin C
What is a macule?
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