Anatomy and Physiology Chapter 5

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  1. Integumentary system functions:
    • Body temperature regulation
    • Blood reservoir
    • Protection
    • Sensation
    • Excretion and Absorption
    • Metabolic functions
  2. Skin Structure:
    • Epidermis: thin surface layer of stratified squamous epithelium
    • Dermis: deeper, thicker layer of dense irregular connective tissue
    • Hypodermis: technically not part of skin, but subcutaneous layer of adipose connective tissue which connects dermis to underlying fascia
  3. Keratinocyte
    • Most common cell type of epidermis
    • Produces keratin protein
    • 1 month cell life
    • Cell life cycle determined by how quickly cell is pushed towards skin surface through each of the epidermis layers
  4. Stratum Basale
    • Deepest layer of epidermis
    • Separated from dermis by basement membrane
    • Attached to basement membrane by hemidesmosomes
    • Cells are columnar or cuboidal
    • Mitosis occurs in stem cells (to replace cells lost)
    • Cells attached by desmosomes
  5. Stratum Spinosum
    • Superficial to basal layer
    • Several layers of keratinocytes
    • Langerhans cells present in this layer (involved in immune system)
  6. Stratum Granulosum
    • 3-5 rows of cells (cells look darker)
    • Superficial to Stratum Spinosum
    • Start undergoing apoptosis because too far from vascular supply for diffusion of nutrients
    • Cells characterized by keratohyalin granules crowding the cytoplasm
  7. Stratum Lucidum
    • Only present in thick skin
    • Clear band superficial to Spinum Granulosum
    • Appears as a homogenous layer because indistinct outer boundaries
  8. Stratum Corneum
    • Most superficial layer
    • Rows of fused, flattened, dead cells filled with keratin
    • Cells desquamate (dander) but are replaced
  9. Papillary Layer of Dermis
    • Thin, outer layer of dermis which fits closely against epidermis
    • Dermal papillae protrude into epidermal region (form epidermal ridges)
    • Contains capillary loops and receptors for temperature and pressure
  10. Reticular Layer of Dermis
    • Dense bundles of collagen fibers, elastic fibers, fibroblasts, and macrophages
    • Helps dermis to stretch when weight increases
  11. Hypodermis
    • Subcutaneous tissue/superficial fascia
    • Attaches skin to underlying structure
    • Serves as energy reserve
    • Insulates body
    • Adipose connective tissue
    • Lots of blood vessels
  12. Melanin
    • Pigment ranging from yellow -> dark brown
    • Synthesized by melanocytes in epidermis
    • Melanin transfers from melanocytes to keratinocytes
    • # of melanocytes is constant between all individuals
    • Sunlight stimulates increased melanocyte activity
  13. Carotene
    • Yellowish pigment
    • Precursor to vitamin A
  14. Hemoglobin
    • Blushing occurs with capillary expansion
    • Oxygenated hemoglobin = pink tint; non-oxygenated hemoglobin = blue skin (cyanosis)
  15. Hair Follicle Cycle
    • Active periods of mitosis alternating with inactivity (regression/resting)
    • Inactivity: hair detaches from matrix (hair loss)
    • Different cyclic activity in different parts of body
  16. Hair Types
    • Lanugo: fetal hair that falls out before birth or is converted to terminal hair
    • Vellus: peach fuzz
    • Terminal: coarse pigmented
  17. Hair Position
    • Normal position of hair follicle and hair is oblique angle to skin surface
    • Arrector pilli muscle: band of smooth muscle extending diagonally - contraction (autonomic control) leads to hair standing up
  18. Sebaceous Gland
    • At least one associated with each hair follicle
    • Sebum: oily substance secreted onto hair surface to prevent hair/skin from drying
    • Stimulated by testosterone
    • Most hairless regions lack sebaceous glands (but in lips sebaceous glands are independent of hair follicles)
    • All are holocrine glands
  19. Sweat Glands
    • Sudoriferous glands
    • Present in most areas of skin
    • 2 types: eccrine and apocrine
  20. Eccrine Sweat Glands
    • Most common
    • Empty on skin surface
    • Merocrine glands - most common secretion
    • Used for thermoregulation
    • Secretes a water solution with salt and urea
    • Stimuli for secretion: heat, muscular activity, stress
    • Diaphoresis: sweating with visible wetness (sign of heart attack)
  21. Apocrine Sweat Glands
    • Found in: axilla, anus, scrotum, labia majora
    • Larger of the two sweat gland types
    • Empty into hair follicle instead of on skin surface
    • Secretion contains lipids and proteins
    • Stimuli for secretion: same as for eccrine, but especially stress
    • Ceruminous Glands: produce ear wax, modified apocrine glands
  22. Deep Wound Healing
    • Four phases
    • Inflammatory: vasodilation, increased vascular permeability; increased white blood cells
    • Migratory phase: scab, epithelial and granulation tissue production?
    • Proliferative phase: scar tissue formed (fibrosis)
    • Maturation phase: resurfaced epithelium
  23. Burns
    • First Degree: only affects epidermis
    • Second Degree: affects epidermis and dermis, but not necessarily accessory structures
    • Third Degree: affects down to the hypodermis
  24. Basal Cell Carcinoma
    • Orginates in basal layer of epidermis
    • Least likely to metastasize
    • Most common form of skin cancer
  25. Squamous Cell Carcinoma
    • Orginates in stratum spinosum
    • Second most common form of skin cancer
    • Detect early and remove to prevent metastasis
  26. Malignant Melanoma
    • Least common form of skin cancer
    • Originates from a mole - increased melanin from melanocytes
    • Most likely to metastasize
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Anatomy and Physiology Chapter 5
2012-02-12 21:56:49
anatomy physiology integumentary system

Chapter five of anatomy and physiology I.
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