Health Science Science Nursing MEDICAL NEUROSCIENCE Early Brain Development 1.For the developing central nervous system, what is the most significant achievement of neurulation ?

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Question MEDICAL NEUROSCIENCE Early Brain Development 1.For the developing central nervous system, what is the most significant achievement of neurulation? a. formation of the neural... tube b. neurogenesis of the vast majority of the neurons that are now resident in your brain c. formation of the notochord d. apoptosis of neurons that fail to acquire target-derived trophic support e. migration of neural crest cells 2.Sonic hedgehog (Shh) is a powerful inductive signal secreted by the notochord and the floorplate. Which of the following statements about Shh is most accurate? a. High levels of Shh compete with neurotrophins for activation of the Trk family of cell surface receptors. b. Low levels of Shh induces the activation of caspase-3 and apoptotic cascades. c. Shh influences the subsequent expression of early transcription factors that mutually suppress the expression of one another in ventral regions of the neural tube. d. High levels of Shh induces the differentiation of the neural crest. e. High levels of Shh promote the growth and survival of neurons and their processes. 3.Which of the following phrases best characterizes the sequence of development for the cortical plate (cerebral cortex)? a. sunnyside-up b. first-come, first-served c. inside-out d. outside-in e. upside-down f. rightside-up 4.Which of the following statements is most accurate concerning neural stem cells? a. Neural stem cells are undergoing mitosis at the greatest rate during the first year of postnatal life. b. Embryonic neural stem cells migrate to the developing cortical plate where they undergo mitosis. c. Embryonic neural stem cells undergo asymmetrical cell division, with each cycle of mitosis giving rise to one presumptive glial cell and one presumptive neuron. d. Neural stem cells persist into adulthood in the outermost layers of the cerebral cortex throughout the cortical mantle. e. The timing of the final cell division of neural stem cells is important for specifying the identity and final location of presumptive excitatory neurons in different layers of the cerebral cortex. 5.Which of the following characterizations of growth cones in the developing nervous system is most accurate? a. Growth cones are quiescent, metabolically speaking, and therefore lack mitochondria. b. Growth cones are highly dynamic structures that contain an abundance of G-actin, actin filaments, microtubule subunits, and tubulin-binding proteins. c. Growth cones are insensitive to the local chemical environment of the developing nervous system. d. Growth cones are restricted to the specialized endings of developing dendrites. e. Growth cones are static structures that serve to anchor mature axons to the extracellular matrix. 6.Which of the following statements concerning tropic molecules is most accurate? a. Tropic molecules are especially critical for the establishment of the one-to-one ratio of preganglionic parasympathetic neuron input to ganglionic neurons that lack dendrites. b. Tropic molecules are especially critical for the establishment of the one-to-one ratio of motor neuron input to muscle fiber in developing skeletal muscle. c. Tropic molecules may attract or repel growing axons, depending on the molecule in question and the receptors with which it interacts. d. Tropic molecules are the object of activity-dependent competition in critical periods during development. e. Tropic molecules are especially critical for the nourishment and survival of rapidly growing axons. f. Tropic molecules differ from trophic molecules because tropic molecules are cell-associated while trophic molecules are freely diffusible in the extracellular space. 7.Which of the following statements concerning trophic molecules is most accurate? a. Trophic molecules, when present in excess in an unprocessed form, induce excitotoxicity. b. Trophic molecules help to match the numbers of efferent and afferent neurons with the amount of target tissue that is present in the periphery. c. Trophic molecules, when present in excess in a processed form following proteolytic cleavage, trigger apoptotic cascades within immature neurons. d. Trophic molecules guide the growth of axons from the nasal retina across the optic chiasm. e. Trophic molecules guide the growth of second-order, anterolateral system axons toward and across the ventral midline of the developing spinal cord, and then enforce a 90-degree, rostral bend in their trajectory of growth. 8.Which of the following functions is attributable to the activity of neurotrophins? a. attract the growth of elongating axons to a certain region of the developing CNS or PNS b. repel the growth of elongating axons to a certain region of the developing CNS or PNS c. establish the appropriate degree of convergence/divergence between neurons and their targets d. promote the collapse of growth cones that enter a loca [Show More]

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