Chapter 5 - Integumentary System Flashcards
What does the skin include?
Epidermis & Dermis
What 2 structures does the integumentary system include?
- Skin/Cutaneous Membrane
2. Accessory Structures
What are the 5 Accessory Structures?
- Hair
- Oil glands
- Sweat glands
- Nails
- Sensory receptors
The skin is a large organ composed of 4 tissue types. What are these 4 tissue types?
- Nerve
- Epithelial
- Connective
- Muscular
How thick is the skin on most of the body?
1-2mm thick
What are the 6 functions of the skin?
- Regulates/maintains body temperature
- Stores blood
- Protection from external environment
- Detects cutaneous sensations/provides sensory information about the surrounding environment
- Excretes & absorbs substances
- Synthesizes Vit. D
What’s the difference between the Epidermis & the Dermis?
EPIDERMIS:
- superficial, thinner
- contains epithelial tissue
- avascular
DERMIS:
- deep, thicker
- contains connective tissue
- vascular
What is deep to the dermis & NOT part of the skin?
Subcutaneous layer/Hypodermis
What does the subcutaneous layer/hypodermis consist of?
Areolar & Adipose tissue
What is the function of the subcutaneous layer/hypodermis?
- fat storage
- area for blood vessel passage
- area of pressure-sensing nerve endings
What is the epidermis primarily composed of?
Stratified squamous epithelium
What are the 4 Principle Cells of the Epidermis?
- Keratinocytes
- Melanocytes
- Langerhans cells (small fraction of epidermal cells)
- Merkel cells (least numerous of epidermal cells)
What are the 2 functions of Keratinocytes?
- produce KERATIN (w/c protects skin & underlying tissue from heat, microbes & chemicals)
- produce LAMELLAR GRANULES (w/c act as a waterproof sealant)
What is the function of Melanocytes?
-produce the pigment MELANIN (skin colour & absorbs UV light)
Where do Langerhan Cells derive from & what is the function?
- derived from RBM
- participate in immune response
What are the 2 functions of Merkel Cells?
- Contact a tactile Merkel disc (sensory structure)
2. Detect touch sensations
What are the 5 layers of the Epidermis (deep to superficial)?
- Stratum Basale/Germinativum
- Stratum Spinosum
- Stratum Granulosum
- Stratum Lucidum
- Stratum Corneum
What is the Stratum Basale/Germinativum?
- deepest layer
- single row of Cuboidal/Columnar Keratinocytes
- contains Merkel cells, Melanocytes, Keratinocytes & continuously dividing Stem cells (produce keratinocytes)
In the Statum Basale/Germinativum, Keratinocytes have a cytoskeleton called what? What does it form?
- Tonafilaments/Keratin Intermediate Filaments
- form the protein Keratin in most superficial layers
How do cells attach in the Stratum Basale/Germinativum?
-attach to each other & basement membrane via Desmosomes & Hemidesmosomes
When the germinal portion of the epidermis is destroyed, new skin can’t regenerate. What is required for healing?
Skin graft
What is the Stratum Spinosum? How do cells attach?
8-10 cell layers held together
-via Desmosomes (provides skin strength & flexibility)
What happens to the cells & what is the appearance of Stratum Spinosum during slide preparation?
cells SHRINK & appear SPINY
In the Stratum Spinosum, what is taken in by keratinocytes via phagocytosis?
Melanin
What are present in the Stratum Spinosum?
- Langerhans cells
- Projection of Melanocytes
What is the Stratum Granulosum? What does it undergo?
3-5 layers of flat dying cells
- transition between deeper, metabolically active strata & dead cells of more superficial strata
- undergo “apoptosis” (show nuclear degeneration)
In the Stratum Granulosum, what do keratinocytes contain?
- Dark-staining granules of the protein Keratohyalin (w/c converts tonofilaments into keratin)
- Lamellar granules (release lipid w/c repels water)
What is the Stratum Lucidum?
4-6 layers of clear, flat, dead cells
The Stratum Lucidum is present only where?
- Fingertips
- Palms of hands
- Soles of feet
What is the function of the Stratum Lucidum?
Provide additional level of “toughness” to thick skin
What is the Stratum Corneum? What is it surrounded by?
25-30 layers of flat dead cells filled with Keratin
-surrounded by Lipids
What does lamellar granules in the Stratum Corneum do?
Make the layer water-repellant
The Stratum Corneum acts as a barrier to what 5 things?
- light
- heat
- water
- chemicals
- bacteria
Constant exposure of the Stratum Corneum to friction causes what?
Increase in depth with the formation of Callus (abormal thickening of skin)
Stem cells divide to produce what?
Keratinocytes
As keratinocytes are pushed up towards the surface, they will fill with what?
Keratin
What is Keratinization? When does it occur?
- Replacement of cell contents with the protein Keratin
- Occurs as cell move to the skin surface over 4-6 weeks
What play roles in epidermal growth?
- Epidermal Growth Factor (EGF)
- other hormone-like proteins
What is the Dermis?
- Connective tissue layer composed of Dense Irregular CT
- Thicker than the epidermis; thickness varies, thickest in soles/palms
The dermis contains what 6 components?
- Fibres
- Cells
- Hair follicles
- Glands
- Nerves
- Blood vessels
What 2 fibres are in the dermis?
- Collagen fibres
2. Elastic fibres
What are collagen fibres?
Parallel bunches that allow for strength/resist pull, but allow flexibility
What are elastic fibres?
Fibres that are strong, but can stretch 150%
What 3 cells are in the dermis?
- Fibroblasts
- Macrophages
- Fat cells
What does fibroblasts do?
Secrete fibres & ground substance of extra cellular matrix
What does macrophages do?
Engulf bacteria & cellular debris via phagocytosis
What does fat cells do?
Store triglycerides
In what other type of tissues in the body might you find collagen fibres?
- bone
- cartilage
- ligaments
- tendons
In what other type of tissues in the body might you find elastic fibres?
- blood vessels
- lung tissue
What is Elasticity?
The ability to return back to original shape
What is Extensibility?
The ability to stretch
What is Tensile strength?
Resists pulling/stretching forces
What are the 2 major regions of the dermis?
- Papillary region
2. Reticular region
What is the papillary region?
- thin collagen & elastic fibres
- surface area is increased by finger-like projections called Dermal Papillae
What are the 3 functions of Dermal Papillae (ie. epidermal ridges) ?
- Anchors epidermis to dermis
- Contain capillaries that feed epidermis
- Contains Meissner’s corpuscles & Free nerve endings
What sensation is associated with Meissner’s corpuscles?
Touch
What 5 sensations is associated with free nerve endings?
- Heat
- Cold
- Pain
- Tickle
- Itch
What are the percentages for the 2 major regions of the dermis?
Papillary region: Top 20%
Reticular region: Bottom 80%
The reticular region is attached to what?
Subcutaneous layer
What are the 10 components of the reticular region?
- Thick collagen fibres
- Fibroblasts
- Wandering cells (ie. Macrophages)
- Some adipose cells in deepest regions
- Blood vessels
- Nerves
- Sebaceous glands
- Suderiferous glands
- Ducts
- Hair follicles
What 6 components in the reticular region occupy spaces between fibers?
- Blood vessels
- Nerves
- Sebaceous glands
- Suderiferous glands
- Ducts
- Hair follicles
What does the combination of collagen & elastic fibers in the reticular region do?
Give the skin strength, extensibility & elasticity
What does epidermal ridges create?
A strong bond between epidermis & dermis in regions of high mechanical stress
What does the increased surface area in epidermal ridges do?
- increase friction for better grip
- increase number of Meissner’s corpuscles w/c increase tactile sensitivity
- create fingerprints
What are the 3 pigments in the dermis?
- Melanin
- Carotene
- Hemoglobin
Where is Melanin produced?
Epidermis
What produces Melanin?
Melanocytes
Melanocytes convert what to melanin?
Tyrosine
What increases melanin production?
UV in sunlight
Carotene is found where?
- Stratum Corneum
- Dermis
What colour is Carotene?
Yellow-orange
What is Hemoglobin?
Red, oxygen-carrying pigment in blood cells
UV exposure increases what?
Melanin production
What’s does Melanin do?
- gives tanned appearance
- protects body from UV damage
- absorbs UV radiation (protects damage to epidermal cell DNA)
How is does a skin tan fade?
When dead keratinocytes shed from Stratum Corneum
What is a Callus?
Abormal thickening of Stratum Corneum
A callus is the result of what?
Constant exposure of skin to friction that stimulates cell & keratin production
What is dandruff?
Excessive keratinized cells that shed skin from scalp
What is psoriasis?
- Chronic skin disorder characterized by more rapid division & movement of keratinocytes through epidermal strata.
- Immature keratinocytes produce abnormal keratin that forms flaky silvery scales
Psoriasis is most common in what 3 areas?
- Knees
- Elbow
- Scalp
What is indicated if new skin can’t regenerate (Stratum Basale & its stem cells are destroyed)?
Skin graft
What are the 2 types of skin graft?
- Autograft (self)
2. Isograft (twin)
What are Striae/Stretch marks?
Ruptured small dermal blood vessels when skin is overstretched & lateral bonds between collagen fibres break
What are tension lines/lines of cleavage?
- Collagen fibres in reticular region orient in one direction
- Indicate predominant direction of underlying collagen fibres
What are freckles?
- genetic predisposition
- melanin accumulates in patches, reddish brown
What are age spots/liver spots?
- flat blemishes, light brown to black (darker than freckles)
- accumulations of melanin over time d/t sunlight
- M/C over 40
What is a mole/nevus?
- round, flat/raised benign overgrowth of melanocytes
- develops in childhood/adolescence
What is albinism?
- Inherited inability to produce melanin d/t melanocytes inability to produce tyrosinase
- Melanin not present in hair, eyes, skin
- Affects vision & sunburn easily
What is vitiligo?
- Complete/partial loss of melanocytes from patches of skin (white skin)
- May be d/t an autoimmune response in w/c antibodies attack melanocytes
What is jaundice?
- yellowish colour to skin & whites of eyes
- buildup of yellow bilirubin in blood from liver disease
What is cyanosis?
- bluish colour to nail beds & skin
- hemoglobin depleted of oxygen (purple-blue)
What is pallor?
Paleness maybe d/t shock/anemia
What is erythema?
- redness of skin d/t enlargement of capillaries in dermis
- during inflammation, infection, allergy or burns
If one is dark skinned, where do you look for circulation issues?
- nail beds
- gums
What is transdermal drug administration?
Method of drug passage across epidermis & into blood vessels of dermis
Where is drug absorption most rapid?
Areas where skin is thin (scrotum, face & scalp)
What are pressure ulcers/decubitus ulcers/bedsores?
Constant deficiency of blood to tissues overlying a bony projection that’s subjected to prolonged pressure
What is eczema?
- inflammation of skin characterized by red, blistering, dry, extremely itchy skin
- cause is idiopathic; linked to genetics & allergies
Where does eczema mostly occur?
In skin creases of wrist, backs of knees & fronts of elbows
