1. Homeostasis
    • Homeostasis: process by which an organism maintains its internal environment within a narrow range of conditions for optimal cell function in the face of a changing external environment
    • Although the word homeostasis implies a static, unchanging state, the internal environment is actually in a state of dynamic constancy

  2. Endoderm
    generate most of their heat through metabolic reactions
  3. Ectoderm
    derive body heat from the enviorment, and maintain this heat by occupying a constant enviorment or by behavioral activities such as basking in the sun
  4. 4 major categories of animal tissues
    • epithelial
    • connective
    • muscle
    • nerve
  5. Epithelial
    • Glands: classified into two categories
    • Exocrine glands: secrete substances into a body cavity or onto the body surface, usually through a duct (sweat, salivary)

    • Endocrine glands: lack ducts, and typically release hormones into the extracellular fluid, which then diffuses into nearby capillaries (hormones)
  6. Connectie tissue
    Loose CT: most abundant (attaches skin to basement)

    Dense CT: collagen fibers (tendons, ligaments)

    • Specialized CT: cartilage, bone, fat, blood, lymph
  7. Muscle Tissue
    • Skeletal muscle: stimulated by nervous system; voluntary control

    Cardiac muscle: involuntary (gap junctions)

    • Smooth muscle: walls of digestive, respiratory tracts etc; typically involuntary
  8. Nerve Tissue
    • Neurons are specialized to generate electrical signals and to conduct these signals to other neurons, muscles, or glands (dendrites, cell body, axons)

    • Glial cells surround, support, insulate, and protect neurons

  9. Organ Systems
    • Organs include two or more interacting tissue types
    • Organs are formed from at least two types of tissues that function together; most organs consist of all four tissue types
    • Most organs function as part of an organ system
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