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49.1 The bodies of vertebrates are organized into functional systems.
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• The vertebrate body is organized into cells, tissues, organs, and organ systems, which are specialized for different functions.
• The four primary tissues of the vertebrate adult body-epithelial, connective, muscle, and nerve-are derived from three embryonic germ layers.
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1. What is a tissue? What is an organ? What is an organ system?
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49.2 Epithelial tissue forms membranes and glands.
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• Epithelial membranes cover all body surfaces.
• Stratified membranes, particularly the keratinized epithelium of the epidermis, provides protection, whereas simple membranes are more adapted for secretion and transport.
• Exocrine glands secrete into ducts that conduct the
secretion to the surface of an epithelial membrane; endocrine glands secrete
hormones into the blood.
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2. What are the different types of epithelial membranes, and how do they differ in structure and function?
3. What are the two types of glands, and how do they differ in structure and function?
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49.3 Connective tissues contain abundant extracellular material.
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• Connective tissues are characterized by abundant extracellular matrix, which is composed of fibrous proteins and a gel-like ground substance in connective tissue proper.
• Loose connective tissues contain many cell types such as adipose cells and mast cells; dense regular connective tissues form tendons and ligaments.
• Special connective tissues include cartilage, bone,
and blood. Nutrients can diffuse through the cartilage matrix but not
through the calcified matrix of bone, which contains canaliculi for that
purpose.
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4. What feature do all connective tissues share? What are the different categories of connective tissue? Give an example of each.
5. What is the structure of a ligament? How do cartilage and bone differ? Why is blood considered to be a connective tissue?
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49.4 Muscle tissue provides for movement, and nerve tissue provides for control.
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• Smooth muscles are composed of spindle-shaped cells and are found in the organs of the internal environment and in the walls of blood vessels.
• Skeletal and cardiac muscles are striated; skeletal muscles, however, are under voluntary control whereas cardiac muscle is involuntary.
• Neurons consist of a cell body with one or more dendrites and one axon. Neuron cell bodies form ganglia, and their axons form nerves in the peripheral nervous system.
• Neuroglia are supporting cells with various functions
including insulating axons to accelerate an electrical impulse.
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6. From what embryonic tissue is muscle derived? What two contractile proteins are abundant in muscle? What are the three categories of muscle tissue? Which two are striated?
7. Why are skeletal muscle fibers multinucleated? What is the functional significance of intercalated discs in heart muscle?
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