Unit 3 Integumentary System

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Unit 3 Integumentary System
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  1. Review: Functions
    • Protection 
    • –abrasion, ultraviolet light, pathogens 

    • Sensation
    • –sensory receptors to detect touch, pressure, pain, temperature 

    • Temperature regulation
    • –changes in blood flow through cutaneous blood vessels (vasodilation and vasoconstriction)
    • °blood reservoir (8-10% of total body flow)
    • •Vitamin D synthesis
    • •Excretion of wastes (in sweat; minor role)
  2. Review: Cutaneous Membrane (Skin) 

    *Figure 5.1 p.150
    • Consists of
    • Epidermis: outer epithelial layer, and 
    • Dermis: underlying connective tissue (CT) layer 

    • ***Hypodermis =subcutaneous tissue or superficial fascia 
    • is not part of skin, but it shares some of skin’s protective functions
    • •consists of areolar and adipose CT
    • •Pacinian corpuscles
    • used to estimate total body fat
  3. Review: Epidermis
    •keratinized stratified squamous epithelium 

    • protects against:
    • abrasion (keratin=fibrous protein)
    • diseases by providing intact barrier against entry of pathogens
    • water loss (glycolipid)

    • cells:
    • keratinocytes
    • –melanocytes
    • –Merkel cells
    • –Langerhans’ cells
  4. Review: Epidermis

    *Table 5.1 p. 151
    *Figure 5.2 p. 152
    *Figure 5.3 p. 153
    • Four or five major layers (from bottom up) 
    • •stratum basale
    • •stratum spinosum
    • •stratum granulosum
    • stratum lucidum - only in thick skin
    • stratum corneum

    Thickness
    of epidermis determines skin types:

    • Thick skin
    • –stratum basale
    • –stratum spinosum
    • –stratum granulosum
    • –stratum lucidum
    • –stratum corneum

    • Thin skin
    • –stratum basale
    • –stratum spinosum
    • –stratum granulosum
    • –stratum corneum
  5. Review: 
    Stratum basale (S. germinitivum)

    *Figure 5.4 p. 153
    • •single layer of cuboidal or columnar cells at basement membrane 
    • •mitotically active cells

    What does it mean?

    • –keratinocytes
    • –melanocytes
    • –Merkel cells 

    Name the function of each cell type.
  6. Review: Stratum spinosum

    *Figure 5.3 p. 153
    • •8-10 cell layers thick 
    • •cells appear spiny 
    • –keratinocytes
    •       °keratin 
    • –Langerhans’ cells
  7. Review: Stratum granulosum

    *Figure 5.3 p. 153
    • •2-5 cell layers thick 
    • •cells continue to flatten due to accumulation of keratin (waterproofing) 
    • •nuclei and organelles begin to degenerate
  8. Review: Stratum lucidum

    *Figure 5.3 p. 153
    • Stratum lucidum 
    • •present only in thick skin 
    • –palms, soles, fingertips
    • •consists of 3-4 layers of translucent dead cells
  9. Review: Stratum corneum

    *Figure 5.3 p. 153
    • Stratum corneum 
    • •consists of 25+ layers of dead (cornified) cells
    •     –filled with keratin
    • •cells are continually shed
  10. Review: Dermis

    *Figure 5.1 p. 150  

    *Table 5.1 p. 151
    • Papillary region:
    • –consists of areolar CT 
    • –structures: 
    •       °Meissner’s corpuscles 
    •       °dermal papillae 

    • Reticular region: 
    • –consists of dense irregular and adipose CT 
    • –structures: 
    •      °Pacinian corpuscles 
    •      °hair follicles 
    •      °sebaceous (oil) glands 
    •      °sudoriferous (sweat) glands
  11. Unique facts: Dermis

    *Figure 5.5 p. 156
    • •Cleavage (tension) lines– elastin & collagen fibers in dermis are oriented in same direction 
    • –important when incisions are made 
    •      
    • °parallel to cleavage line – faster healing, less scar 
    • °across cleavage line – slower healing, more scar tissue 

    • •Stretch marks – overstretched skin --> dermis ruptures --> scar tissue visible through epidermis
    • •Uses of dermis
    • –site of some skin tests 
    • –to make leather
  12. Practice Questions
    1. The design of a person’s epidermal ridges is determined by the manner in which the papillae rest upon the dermal ridges to produce the specific pattern known as handprints, footprints, and fingerprints.  Which of the following statements is true regarding these prints or ridges? 

    • A.every human being has the same pattern of ridges
    • B.they are genetically determined; therefore, unique to each person
    • C.because we are constantly shedding epithelial cells, these ridges are changing daily
    • D.identical twins do not have the same pattern of ridges
  13. Skin Color
    • •Color is due to pigments 
    • melanin – yellow to black 
    • carotene – yellow 
    • hemoglobin – reddish 
    • °cyanosis – bluish color due to lack of oxygen 

    • •Defects
    • albinism – no melanin (photoprotective pigment)
    • vitiligo – little or no melanin in certain areas of the body
  14. Evolution of Skin Color
    There is strong correlation between skin color & strength of sunlight across the globe. 

    •people who live in the north evolved fair skin --> absorb more UV light for adequate production of  vitamin D

    • •people in the tropics evolved dark skin to block out sun and protect their folate reserves
    • °UV light cuts folate levels in skin (folate is crucial for CNS development)
  15. Skin Tanning
    •caused by exposure to UV radiation that increases production of melanin by melanocytes and spreading of melanin to keratinocytes 

    --melanin evolved to absorb or disperse UV light
  16. Disorders - Skin Cancer: 

    *Figure 5A p. 154
    • Basal cell carcinoma 
    • •cells of stratum basale 
    •       – invade dermis and hypodermis 
    • •slow growing, least malignant, most common; face; 

    • Squamous cell carcinoma
    • •stratum spinosum (keratinocytes) 
    • •grows rapidly and metastasizes 
    • •scalp, ears, lower lip, and hands 
  17. Disorders - Skin Cancer: Melanoma

    *Figure 5a p. 154
    • •cancer of melanocytes 
    • •most dangerous
    • •metastasizes rapidly to lymph and blood vessel
  18. Accessory Skin Structures
    • •Hair 
    • •Glands
    • •Nails
  19. Hair

    *Figure 5.6 p. 158
    • •keratinized cells originating in follicle 
    •     –bulb
    •     –root hair plexus
    • •shaft 
    • •root 
    • •arrector pili muscle
  20. Hair: Types and Growth
    • •Types 
    • –vellus - pale, fine body hair
    • –terminal - longer, darker hair of eyebrows, scalp, axillary and pubic area

    • •Hair growth
    • –growth stage: eyelashes – 30 days
    •                       scalp hair – 3 years
    • –resting stage: eyelashes –105 days
    •                       scalp hair – 1-2 years

    • •Stimulation of growth
    • –terminal hairs stimulated by presence of androgens
  21. Hair Color
    • Primarily due to melanin: 
    • •black-brown melanin --> black hair 
    • •red melanin -->= red hair 
    • •less of black-brown & red melanin --> blonde hair 
    • •gray/white hair 
    •    –lack of pigment (melanin) 
    •    –presence of air bubbles in the medulla (core) of hair shaft
  22. Disorders of Hair Growth
    • Hirsutism - excessive hairiness 
    • Alopecia - hair thinning with some degree of baldness 
    • Male pattern baldness - genetically determined 
    •   –Minoxidil (antihypertensive )
  23. Sebaceous (Oil) Glands

    *Figure 5.7 p. 162
    • •secrete sebum (holocrine glands) 
    •     –lubricate &protect hair 
    •     –kills bacteria (bactericidal) 
    • •found everywhere EXCEPT palms and soles 
    • •location:
    •   -most glands are connected to hair follicle 
    •   –some open directly onto skin surface (lips, eyelids, genitalia) 

    • whiteheads - accumulated sebum in blocked duct
    • blackheads - oxidized & dry sebum
    • acne - inflammation of oil glands
  24. Sudoriferous (Sweat) Glands

    *Figure 5.7 p. 162
    • •found in all regions EXCEPT nipples &parts of external genitalia 
    • eccrine (merocrine) glands 
    •   –secrete mostly water with some salts, ammonia, urea, uric acid & lactic acid 
    •    -palms, soles, forehead 

    • apocrine glands 
    •    –secretions contain organic substances (body odors) 
    •   –axillary, anogenital areas
  25. Other Glands
    • ceruminous glands 
    •   –modified merocrine sweat glands 
    •   –secrete cerumen=earwax of external ear canal 
    •      --protect tympanic membrane (eardrum) 

    • mammary glands
    •   -modified apocrine sweat glands 
    •   –produce milk
  26. Nails

    *Figure 5.8 p. 162
    • •Stratum corneum that contain keratin 
    • Functions
    •   –protect dorsal surfaces of digits 
    •   –aid in manipulation and grasping small objects 
    • •nail root extends from nail matrix
  27. As you age…

    *Figure 5.10, p. 165
    • 1.Skin becomes translucent… 
    • 2.Susceptible to sunburn, skin cancer, and lighter hair color…
    • 3.Slow healing and wrinkles…
    • 4.Susceptible to hemorrhages and ulcers…
    • 5.Dry, coarse and itchy skin…
    • 6.Decreased ability to regulate body temperature & intolerance to cold…
    • 7.AGE SPOTS form?

    Why???
  28. As you age...answers
    • 1.Skin becomes translucent… thinning of epidermis 
    • 2.Susceptible to sunburn, skin cancer, and lighter hair color… melanocyte activity decreases
    • 3.Slow healing and wrinkles… dermis becomes thinner, less collagen & elastic fibers
    • 4.Susceptible to hemorrhages and ulcers… fewer blood vessels and slower rate of repair
    • 5.Dry, coarse and itchy skin… activity of sebaceous glands
    • 6.Decreased ability to regulate body temperature & intolerance to cold… sweat gland activity decreases
    • 7.The number of functioning melanocytes generally decreases; however…..
    • –in some areas, hands and face, melanocytes increase in number resulting in… AGE SPOTS (not to be confused with freckles caused by increase in melanin production)
  29. Review: Skin Burns

    *Figure 5B, p. 160 

    *Figure 5C, p. 161
    injury to tissue caused by heat, cold, friction, electricity, radiation, or chemicals, all of which denature cell proteins and cause cell death 

    • •severity depends on
    •   –extent (Rule of Nines)
    •   –degree (depends on which layer(s) of skin are involved)
  30. Skin Burns: Complications
    • •result from: 
    •   –dehydration (#1)
    •   –electrolyte & protein imbalance 
    •   –infections 
    •   –renal shut down 

    How dehydration contributes to the other complications?
  31. Practice Questions
    The glands that serve an important function in thermoregulation: 

    • a. keratinocytes
    • b. sudoriferous
    • c. sebaceous
    • d. mammary
  32. Let’s apply
    •The temperature yesterday was an uncomfortable 98 F.  You unwisely chose to play tennis at noon, counting on your body’s internal defenses to protect you against heat exhaustion. 

     How did your body respond to this distress?
  33. Let’s apply: Answer
    •The thermoreceptors in the skin relayed a message to the brain; the hypothalamus responded by sending impulses to sweat glands, which released their watery products --> evaporated and cooled the body. 

    Blood vessels in the dermis responded to neural stimulation by dilating and releasing heat to the exterior.

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