1 A) heart, cardiac muscle cell, cardiac muscle B) heart, cardiac muscle, blood C) heart, blood, blood vessels D) blood vessels, blood E) heart, lungs, blood vessels 2 A) very thin, to aid in the diffusion of substances B) thick with many cilia C) rich in specific transport channels D) thick and mucus-secreting 3 A) stem cells B) chondrocytes C) osteocytes D) fibroblasts E) amoebocytes 4 A) by varying the rate of nerve impulses B) by stimulating different numbers of muscle fibers C) by rapid firing of motor neurons D) by varying the amount of neurotransmitters released E) by antagonistic interactions between muscle cells 5 A) transmit nerve impulses. B) are only found in the central nervous system. C) are only found in the peripheral nervous system. D) are associated with axons and form an insulated covering. E) form ganglia. 6 A) endocrine, circulatory, urinary, respiratory B) immune, endocrine, sensory, circulatory C) digestive, circulatory, urinary, respiratory D) circulatory, urinary, respiratory, reproductive E) circulatory, endocrine, respiratory 7 A) errors in nerve impulses B) different effectors that have opposing actions C) different effectors that have reinforcing actions D) effectors that work in a sequence E) only occur in the musculoskeletal system
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