Concept explainers
To describe: Mechanism involved in the action of antidepressant medication (molecules).
Introduction: Antidepressant molecules are used to reduce stress and alleviate mood. The exact mechanism of action is not known, but their action at the chemical synapse is well known. Synapse helps in the conduction of electrical impulse by the presence of neurotransmitters.
To describe: Mechanism involved in action of antidepressant medication (molecules).
Introduction: Antidepressant molecules are used to reduce stress and alleviate mood. The exact mechanism of action is not known, but their action at the chemical synapse is well known. Synapse helps in the conduction of electrical impulse by the presence of neurotransmitters.
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Biology (MindTap Course List)
- Visit this site (http://openstaxcollege.org/l/neurolab) to see a virtual neurophysiology lab, and to observe electrophysiological processes in the nervous system, where scientists directly measure the electrical signals produced by neurons. Often, the action potentials occur so rapidly that watching a screen to see them occur is not helpful. A speaker is powered by the signals recorded from a neuron and it pops each time the neuron fires an action potential. These action potentials are firing so fast that it sounds like static on the radio. Electrophysiologists can recognize the patterns within that static to understand what is happening. Why is the leech model used for measuring the electrical activity of neurons instead of using humans?arrow_forwardWhich of the following statements best describes saltatory conduction? a. It inhibits direct neurotransmitter release. b. It transmits the action potential at the nodes of Ranvier andthus speeds up impulses on myelinated axons. c. It increases neurotransmitter release at the presynapticmembrane. d. It decreases neurotransmitter uptake at chemically gatedpostsynaptic channels. e. It removes neurotransmitters from the synaptic cleft.arrow_forwardWhich of the following does not contribute to propagation of action potentials? a. As the area outside the membrane becomes negative, itattracts ions from adjacent regions; as the inside of the membrane becomes positive, it attracts negative ions from nearby in the cytoplasm. These events depolarize nearby regions of the axon membrane. b. The refractory period allows the impulse to travel in only one direction. c. Each segment of the axon prevents the adjacent segments from firing. d. The magnitude of the action potential stays the same as it travels down the axon. e. Up to a limit, increasing the intensity of the stimulus increases the number of action potentials.arrow_forward
- Watch this video (http://openstaxcollege.org/l/summation) to learn about summation. The process of converting electrical signals to chemical signals and back requires subtle changes that can result in transient increases or decreases in membrane voltage. To cause a lasting change in the target cell, multiple signals are usually added together, or summated. Does spatial summation have to happen all at once, or can the separate signals arrive on the postsynaptic neuron at slightly different times? Explain your answer.arrow_forwardFigure 35.11 Potassium channel blockers, such as amiodarone and procainamide, which are used to treat abnormal electrical activity in the heart, called cardiac dysrhythmia, impede the movement of K+ through voltage-gated K+ channels. Which part of the action potential would you expect potassium channels to affect?arrow_forwardIn the propagation of a nerve impulse: a. the refractory period begins as the K+ channel opens, allowing K+ ions to flow outward along their concentrationgradient. b. Na+ ions flow out of the axon with their concentration gradient. c. positive charges lower the membrane potential to its lowestaction potential. d. gated K+ channels open at the same time as the activationgate of Na+ channels closes. e. the depolarizing stimulus lowers the membrane potential toopen the Na+ gates.arrow_forward
- View the University of Michigan Webscope (http://openstaxcollege.org/l/nervefiber) to see an electron micrograph of a cross-section of a myelinated nerve fiber. The axon contains microtubules and neurofilaments, bounded by a plasma membrane known as the axolemma. Outside the plasma membrane of the axon is the myelin sheath, which is composed of the tightly wrapped plasma membrane of a Schwann cell. What aspects of the cells in this image react with the stain that makes them the deep, dark, black color, such as the multiple layers that are the myelin sheath?arrow_forwardWatch this video (http://openstaxcollege.org/l/neurotrans) to learn about the release of a neurotransmitter. The action potential reaches the end of the axon, called the axon terminal, and a chemical signal is released to tell the target cell to do something, either initiate a new action potential, or to suppress that activity. In a very short space, the electrical signal of the action potential is changed into the chemical signal of a neurotransmitter, and then back to electrical changes in the target cell membrane. What is the importance of voltage-gated calcium channels in the release of neurotransmitters?arrow_forwardAn example of a synapse could be the site where: a. neurotransmitters released by an axon travel across a gap and are picked up by receptors on a muscle cell. b. an electrical impulse arrives at the end of a dendrite causingions to flow onto axons of presynaptic neurons. c. postsynaptic neurons transmit a signal across a cleft to apresynaptic neuron. d. oligodendrocytes contact the dendrites of an afferent neurondirectly. e. an onoff switch stimulates an electrical impulse in apresynaptic cell to stimulate other presynaptic cells.arrow_forward
- 1: Describe the changes in the neuron membrane that occur throughout the course of an action potential. 2: Mention: Resting state, threshold, depolarization, repolarization, and hyperpolarization. 3: mention how the action potential is related to neuron communication.arrow_forward20. Explain how a chemical synapse works when a nerve meets the muscle fiber. address the following concepts -the name of the specific new transmitter, how the neurotransmitter is released from the presynaptic cell into the synapse ,the action of the new transmitter on the receptor on the postsynaptic cell ,and how the levels of neurotransmitters are regulated. be specific and detailed in your responsearrow_forwardExplain the following; If a drug partly blocks a membrane’s potassium channels, how does it affect the action potential? Suppose the threshold of a neuron were the same as the neuron’s resting potential. What would happen? At what frequency would the cell produce action potentials?arrow_forward
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