biol_119_lecture_19_9-23-09

biol_119_lecture_19_9-23-09 - Edge of the Range:...

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Unformatted text preview: Edge of the Range: Conservation of Blandings turtles in northern New York Dr. Glenn Johnson SUNY Potsdam Department of Biology Biology Department Seminar Newton 203 Friday, October 23 2 pm Lecture 19, 10-19-09 Finishing up Chapter 48, and then on to Chapter 49 Review today at 3:30 in Newton 201 There is a premed advisory meeting on Wednesday, October 21, 2009 at 4 PM in Newton 201. We will go over medical school requirements, Dr Beatty from Upstate will present information on Upstate Medical University and their opportunities related to rural health and the ARMY will provide information about their scholarship opportunities for the health- related professions. Refreshments will be available courtesy of the Army. A. Pumps sodium from the cell A. Pumps sodium into the cell B. Pumps potasium from the cell A. Pumps potasium into the cell A. Both A and D B. Both B and C B. Generation of Action Potentials: A Closer Look C. Conduction of Action Potentials At the site where the action potential is generated, usually the axon hillock, an electrical current depolarizes the neighboring region of the axon membrane The speed of an action potential increases with the diameter of an axon In vertebrates, axons are myelinated which also causes the speed of an action potential to increase Conduction Speed Action potentials are normally carried in one direction from the axon hillock to the axon terminals. By using an electronic probe, you experimentally depolarize the middle of the axon to threshold. What do you expect? A. No action potential will be initiated. B. An action potential will be initiated and proceed in the normal direction toward the axon terminal. C. An action potential will be initiated and proceed back toward the axon hillock. A. Two action potentials will be initiated, one going toward the axon terminal and one going back toward the hillock. A. An action potential will be initiated, but it will die out before it reaches the axon terminal. Action potentials are normally carried in one direction from the axon hillock to the axon terminals. By using an electronic probe, you experimentally depolarize the middle of the axon to threshold. What do you expect? A. No action potential will be initiated. B. An action potential will be initiated and proceed in the normal direction toward the axon terminal. C. An action potential will be initiated and proceed back toward the axon hillock. D. Two action potentials will be initiated, one going toward the axon terminal and one going back toward the hillock. E. An action potential will be initiated, but it will die out before it reaches the axon terminal. Concept 48.4: Neurons communicate with other cells at synapses In an electrical synapse electrical current flows directly from one cell to another via a gap junction The vast majority of synapses are chemical synapses In a chemical synapse , a presynaptic neuron releases chemical neurotransmitters , which are stored in the synaptic terminal Figure 48.14 Postsynaptic neuron Synaptic terminal of presynaptic neurons 5 m...
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biol_119_lecture_19_9-23-09 - Edge of the Range:...

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