lecture 20, 2009

lecture 20, 2009 - Lecture 20, 10-21-09 Finishing up...

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Lecture 20, 10-21-09 Finishing up Chapter 49, and then on to Chapter 50, section 50.5
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"Saltatory conduction" means that the membrane potential changes _____. A. only where there is diffusion of sodium and potassium ions B. only at the nodes of Ranvier C. along the entire length of the axon D. in an all-or-none fashion E. from polarized to depolarized and back to polarized
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Glia in the CNS Glia have numerous functions Astrocytes provide structural support for neurons, regulate extracellular ions and neurotransmitters, and induce the formation of a blood-brain barrier that regulates the chemical environment of the CNS Radial glia play a role in the embryonic development of the nervous system Ependymal cells line the ventricles and promote circulation of cerebrospinal fluid Microglia protect the nervous system from microorganisms Oligodendrocytes (CNS) and Schwann cells (PNS) form the myelin sheaths around axons See Figure 49.6, next slide
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Illustration of Glial cells in the CNS
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B. The Peripheral Nervous System The PNS transmits information to and from the CNS and regulates movement and the internal environment In the PNS, afferent neurons transmit information to the CNS and efferent neurons transmit information away from the CNS Cranial nerves (12) originate in the brain and mostly terminate in organs of the head and upper body Spinal nerves (31) originate in the spinal cord and extend to parts of the body below the head
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The efferent portion of the PNS has two functional components: the motor system responds to outside stimuli and the autonomic nervous system (maintains homeostasis The motor system carries signals to skeletal muscles and is voluntary The autonomic nervous system regulates the internal environment in an involuntary manner
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The autonomic nervous system has sympathetic, parasympathetic, and enteric divisions The sympathetic division correlates with the “fight-or-flight” response The parasympathetic division promotes a return to “rest and self- maintenance” The enteric division controls activity of the digestive tract, pancreas, and gallbladder The sympathetic and parasympathetic divisions have antagonistic effects on target organs
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Fig. 49-8 Stimulates glucose release from liver; inhibits gallbladder Dilates pupil of eye Parasympathetic division Sympathetic division Action on target organs: Inhibits salivary gland secretion Accelerates heart Relaxes bronchi in lungs Inhibits activity of stomach and intestines Inhibits activity of pancreas Stimulates adrenal medulla Inhibits emptying of bladder Promotes ejaculation and
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This note was uploaded on 05/04/2011 for the course BIO 119 taught by Professor O'donnellandspear during the Spring '07 term at SUNY Geneseo.

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lecture 20, 2009 - Lecture 20, 10-21-09 Finishing up...

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