Biology Study Guide Final Exam Chapter 48

Biology Study Guide Final Exam Chapter 48 - Study Guide:...

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Study Guide: Final Exam Chapter 48: Nervous System 1. The two coordinating systems in animals are the central nervous system and the peripheral nervous system. The central nervous system consists of a small brain and longitudinal nerve cords, which simple organisms posses. In more complex invertebrates, such as annelids and arthropods, behavior is regulated by more complicated brains and ventral nerve cords containing segmentally arranged clusters of neurons called ganglia. Nerves that connect the CNS with the rest of the animal’s body make up the peripheral nervous system (PNS). 2. The three major functions of a nervous system are sensory input, integration, and motor output. Sensory neurons transmit information from sensors that detect external stimuli. Sensory input is conveyed to the CNS, where interneurons integrate the sensory input. Motor output leaves the CNS via motor neurons, which communicate with effector cells (muscle or endocrine cells). Effector cells carry out the body’s response to a stimulus. The stages of sensory input, integration, and motor output are easy to study in the simple nerve circuits that produce reflexes, the body’s automatic responses to stimuli. 3. The neuron is the structural and functional unit of the nervous system. The neuron’s nucleus is located in the cell body. Dendrites are highly branched extensions that receive signals from other neurons. An axon is a longer extension that transmits signals to neurons or effector cells. Many axons are enclosed in a myelin sheath. Near its end, axons divide into several branches, each of which ends in a synaptic terminal. The site of communication between a synaptic terminal and another cell is called a synapse. At most synapses, information is passed from the transmitting neuron (the presynaptic cell ) to the receiving cell (the postsynaptic cell ) by means of chemical messengers called neurotransmitters. 4. Neurons can be classified as functions because of Glia , which are supporting cells that are essential for the structural integrity of the nervous system and for the normal functioning of neurons. 5. Astrocytes provide structural support for neurons and regulate the extracellular concentrations of ions and neurotransmitters.They also respond to activity in neighboring neurons by facilitating information transfer at those neuron’s synapses. By inducing the formation of tight junctions between capillary cells, astrocytes help form the blood-brain barrier, which restricts the passage of substances into the CNS. Radial glia form tracks along which newly formed neurons migrate from the neural tube. Oligodendrocytes (in the CNS) and Schwann cells (in the PNS) are glia that form myelin sheaths around the axons of vertebrate neurons. These sheaths provide electrical insulation of the axon. 6.
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This note was uploaded on 11/04/2010 for the course BIO 107 taught by Professor Abott during the Fall '09 term at UConn.

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Biology Study Guide Final Exam Chapter 48 - Study Guide:...

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