Ch. 5 Intergumentary System Flashcards
Skin has appendages of
Sweat (sudoriferous) glands
Sebaceous (oil) glands
Hairs and hair follicles
Nails
Skin functions
Protect Regulate body temperature Cutaneous sensation Metabolic function (synthesize V-D precursor) Blood reservoir Excretion
Skin function: Protection
It has 3 types of protective barriers
1 chemical
2 physical
3 biological
It protects deeper tissue from
Mechanical damage: falling, adipose padding
Chemical damage: secretions+ melanin keratin
Bacterial damage: acidic pH on skin stop bacteria
Thermal damage: receptors hot, cold to brain
Ultraviolet radiation: (carcinogen) melanin prevents DNA mutation from the top.
Desiccation: (drying out) prevents loss of fluid, may leak if burned.
Skin Function: Body temp regulation
Negative Feedback:
Too hot start to sweat, too cold erector pili muscle stands up to warm up
Skin Function: Cutaneous Sensation
Receptors for pain, pressure, vibrations, signaling the control center.
Skin function: Metabolic function
Synthesize vitamin precursor
But too much direct sunlight can cause cancer.
Skin Function: Blood reservoir
Holds up to 5% body’s total blood volume, then shunted in circulation used by working muscles and body organs
Skin function: Excretion
Excrete and eliminate sweat and nitrogen-containing wastes (ammonia;due to protein breakdown, urea, uric acid), NaCl, H2O, etc.
Skin structures 3
Epidermis
Dermis
Hypodermis
Skin structure: Epidermis 5
Stratum Corneum Stratum Lucidum Stratum Granulosum Stratum Spinosum Stratum Basale
Epidermis 5 strata
- Stratified squamous epithelium w/ keratin
- cells tightly connected by Desmosomes
- Keratinocytes form several layers
- layers of the epidermis ***
- Melanin
Layers of epidermis: Stratum Corneum
20-30 cell layers thick and accounts for 3/4 of epidermal thickness.
Located at exposed surface of skin
Protective barrier of dead, durable, and expendable cells. (Cells are plasma membrane filled with keratin that is protective.
Thickness will vary depending on use, (calluses can develop on palms of hands and soles of feet.
Glycolipids secreted between cells provides waterproofing and preserves some permeability characteristics of the skin.
Allows for transdermal medications like nicotine patches.
Layers of epidermis:
Stratum Corneum Stratum Lucidum (keratin soles) Stratum Granulosum Stratum Spinosum Stratum Basale
Layers of epidermis: Stratum Basale
Single row of cells that serve as origin of keratinocytes for all superficial strata.
High mitotic activity
Contains melanocytes )accounts for 10-25 of stratum basale cells.
Melanin
Pigment produced by melanocytes
Gets packaged in melanosomes
And then deposited into the keratinocytes in more superficial layers.
Melanin granules then position themselves on superficial or sunny side of keratinocytes nucleus to protect against UV radiation.
Amount produced depends on den ethics and exposure to sunlight.
Cell production of tyrosinase )acts on the amino acid tyrosine) is critical for melanin production.
Albinism; commonly failure to produce tyrosinase
Dermis
2 layers
Strong collagen, flexible (elastic)connective tissue,
Papillary layer: 20%, Thin superficial layer of areolar connective tissue, supports and nourishes overlying epidermis, projections called dermal papillae, pain receptors, capillary loops, rise SA and serves as basis for friction ridges and fingerprints.
Reticular layer: 80%, dense irregular connective tissue and mesh work of collagen and elastic fibers , blood vessels, glands, nerve receptors.
Hypodermis (subcutaneous)
- Not part of the skin
- Anchors skin to underlying organs
- Composed mostly of adipose tissue (half of body’s stored fat)
Appendages of the skin
Sebaceous glands
Sweat (sudoriferous) glands
Hair
Nails
Appendages of the skin: Sebaceous glands
Produce oil (sebum): Softens and lubricates the hair and skin.
Most with ducts that empty into hair follicles.
Distributed body wide except for palms of hands and soles of the feet.
Glands are activated at puberty (under hormonal control) Clinical: acne- accutane is teratogenic
Appendages of the skin: Sweat Glands
Widely distributed 3 million in the body.
Eccrine
Apocrine
Ceruminous Glands
Mammary glands
Eccrine Sweat Gland
Coiled, tubular portion in dermis with opening via duct to pore on the skin surface.
Distributed body wide (most numerous)
Helps dissipate excess heat through evaporative cooling.
Apocrine Sweat Gland
Ducts empty into hair follicles
Localized to axillary and pubic (anogenital) areas only 2000 in number
Activated by stress, pain, & sexual excitement; not temp.
Fatty acid and protein secretion. Bacteria breakdown produces body odor.
Ceruminous Modified Sweat glands
Found in lining of external ear canal
Secretion mixes with sebum to produce cerumen or earwax.
Mammary Modified sweat glands
Not discussed
Appendages of the skin: Hair
- Distributed body wide except palms, soles, lips, nipple, external genitalia
- Strand of dead , hard keratinized epithelial cells projecting from an invaginated tunnel in the epidermal and dermal layers called the hair follicle
- Hair follicle:
A. Tubular invaginations of the epidermis
B. Formed by mitotically active stratum Basale cells
C. Melanocytes provide pigment for hair color
D. Dermal capillaries provide blood supply
Four parts:
Shaft-visible part of hair; projects from surface
Root- part of the hair enclosed in hair follicle
Bulb- growth zone at inferior end of hair follicle
- Arrector pili muscle (smooth muscle)
- Clinical:minoxidal (rogaine)
Appendages of the skin: Nails structure
Nail fold (lateral and proximal skin coverings)
Eponychium (cuticle)
Nail body: sheet of hard keratin attached to nail bed. Lanula -crescent shaped vascular area at proximal end of the nail bed and visible through the nail. Used for visual check of oxygen status in patients.
Clinical: eponychiitis, ingrown toenail
Injection sites
Intradermal (ID): Tb test
Subcutaneous (“subcue” or SQ): Hypodrms adipose.
Intramuscular (IM): in muscle below hypodermis
Intravenous (IV): in vein.
Blisters
Fluid filled pocket between epidermis and dermis. Tissue damage by friction.
Lines of Cleavage
5.4b
Formed by uniform alignment of collagen and elastic fibers
Stretch Marks
Collagen stretched beyond their capability
Decubitus ulcers “Bed Sores”
Blood supply is restricted -> ischemia (O2 reduced) -> necrosis (tissue death)
Bacterial infections result, difficult to heal, secondary intention.
Areas of highest risk are least padded (elbow, heels, backbone) little fat over them
Patients of high risk: elderly in care homes, less fat
Importance of rotating patient positions, artificial padding and clean bedding.
Burns
Tissue damage inflicted by heat, electricity, UV radiation, or chemicals that denature proteins and cause cell death in affected areas.
Dangers associated are loss of fluids lead to: Dehydration
Electrolyte imbalance (muscle contractions)
Renal failure
Circulatory Shock*
Burns: circulatory shock
Loose interstitial fluid, plasma, blood plasma, is going into tissue, gets thick hard to pump.
Burns: Infection
Sepsis (widespread bacterial infection) is leading cause of death in burn victims.
Burns: Rule of Nines
Way to approximate the extent of burns
Special tables are used when greater accuracy is desired
Head
4.5%
4.5%. 4.5%
18%
1%
9%. 9%
9,9,9,36, 18, 18
Severity of Burns
1st degree burn
Only epidermis is damaged
Redness, pain, swelling (inflammation) heat
Heals 2-3 days.
Severity of Burns
2nd degree burns
Damage to Epidermis and Dermis
Redness, pain, swelling (inflammation), heat + Blistering (fluid)
Heals 3-4 weeks
Severity of Burns
3rd degree burns
Total tissue destruction of epidermis, dermis, hypodermis.
Tissue becomes dis colored, but no edema, or pain, no nerves,
Usually requires skin graft.
Skin Cancer
Most common types
Basal cell carcinoma
Squamous cell carcinoma
Malignant melanoma
Clinal Applications
Injection sites Blisters Lines of cleavage Stretch marks Decubitus ulcers "bed sores" Burns Skin cancer
Skin Cancer: Basal cell carcinoma
Bubble growth
Least malignant bit most common type
80% of all skin cancers
Arises from stratum Basale cells that then go and invade the underlying dermis and hypodermis.
Results in a shiny, dome shaped nodule most commonly found in Sun-exposed regions of the face
Slow growing and therefore metastasizes seldom
Full cure by surgical excision in 99% of cases
Skin Cancer: Squamous cell carcinoma
Arises from stratum Spinosum
Results in a scaly reddened papule most commonly on the head (scalp, ears, and lower lip and hands)
Tends to grow rapidly and will metastasize if not removed
Chance of complete cure is good if caught early and removed by surgery or radiation.
Skin Cancer: Malignant Melanoma
Most deadly, but Rare
Accounts for only 5% of all skin cancers but 90% of skin cancer deaths due to metastasis and resistance to chemotherapy
Cancer of melanocytes
Metastasizes rapidly to lymph and blood vessels
Can occur body wide
Most appear spontaneously, but about 1/3 from pre existing moles (wherever there is pigment)
Skin cancer: ABCDE early mole detection
A : asymmetry
B : irregular border
C : color
D : diameter larger than 6mm pencil eraser
E : elevation above skin surface
evolution Changes over time
