answer choices all sodium gates are closed proteins have been resynthesized the Na ions have been pumped back into the cell the membrane potential has been reestablished Question 2 30 seconds Q. b) ganglia membrane exhibits chemically gated ion channels. A) They increase amplitude as they move away from the stimulus point. the membrane One mechanism, the sodium-potassium pump, maintains the resting potential, and another, the various ion channels, helps create the action potential. A second nerve impulse cannot be generated until ________. Hence, more time is taken in generating and then transmitting nerve impulses during an action potential. Neurotransmitter inactivation is carried out by a combination of three processes. True or False, Chapter 11 Fundamentals of the Nervous System and Nervous Tissue (TB). a single type of channel will open, permitting simultaneous flow of sodium and potassium. What does the central nervous system use to determine the strength of a stimulus? In myelinated neurons, ion flows occur only at the nodes of Ranvier. Saltatory is faster than continuous conduction and occurs in myelinated neurons. Owning to the importance of this discovery, he was awarded Noble Prize in 1932. Polarization is the situation in which the membrane is electrically charged but non-conductive. B) stimulate the production of acetylcholine, C) destroy ACh a brief period after its release by the axon endings. Recordings from squid synapses and neuromuscular junctions of the frog reveal a delay of 0.5 to 4.0 milliseconds between the onset of action potential at the nerve terminal and action potential at the postsynaptic site. True or False, A synapse formed between the axon ending of one neuron and the cell body of another neuron is called an axosomatic synapse. Nerve impulse propagates by jumping from one node of Ranvier to the next. farther and farther along the circuit. Any stimulus below this intensity a) motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands A single type of channel will open, permitting simultaneous flow of sodium and potassium. - Studocu Neurons and their thresholds, axons, dendrites, and Na+/K+ ATPases. A&P Chapter 12 The Central Nervous System Flashcards - Easy Notecards ________ are found in the CNS and bind axons and blood vessels to each other. Almost instantly the membrane actually reverses polarity, and the inside acquires a positive charge in relation to the outside. When an action potential reaches the axon terminal of the presynaptic cell, it opens channels that allow calcium to enter the terminal. 5.) b) ligand-gated channel Another factor is the temperature of the nerve fibre. The generation of a second action in some neurons can only The nodes of Ranvier are packed with a high concentration of ion channels, which, upon stimulation, propagate the nerve impulse to the next node. The interior is: lower Axon Ending- Acts as a transmitter of signals. A second nerve impulse cannot be generated until ____ the membrane potential has been reestablished Saltatory conduction is made possible by ________. It refers to a graded potential state because a threshold stimulus of about -55mV causes a change in the membrane potential. The process of transmission of a nerve impulse from one neuron to the other, after reaching the axons synaptic terminal, is known as synapses. are crucial for the development of neural connections. 2.) a second nerve impulse cannot be generated until___ the membrane potential has been reestablished: an impulse from one nerve cell is communicated to another nerve cell via the___ synapse: neuroglia that control the chemical enviroment around neurons by buffering potassium and recapturing neurotransmitters are___ astrocytes True or False, Reflexes are rapid, automatic responses to stimuli. Stimulation of a Which of the following will occur when an excitatory postsynaptic potential (EPSP) is being generated on the dendritic membrane? Since ions cannot cross the lipid content of the myelin sheath, they spread passively down the nerve fibre until reaching the unmyelinated nodes of Ranvier. The sheath of Schwann is also called the ________. An inhibitory postsynaptic potential (IPSP) is associated with ________. An excitatory neurotransmitter secreted by motor neurons innervating skeletal muscle is ________. As a result of this, the membrane becomes hyperpolarized and have a potential difference of -90 mV. Once an action potential has been generated at the axon hillock, it is conducted along the length of the axon until it reaches the terminals, the fingerlike extensions of the neuron that are next to other neurons and muscle cells (see the section The nerve cell: The neuron). At this point there exist two methods for transmitting the action potential from one cell to the other. They are generated when the nerve The nerve impulse travels at a speed of 100 m/s in saltatory conduction. the Na+ ions have been pumped back into the cell. A gap between Schwann cells in the peripheral system is called a(n) ________. 2.) Which of the following will occur when an excitatory postsynaptic potential (EPSP) is being generated on the dendritic membrane? Select the correct statement regarding synapses. Write a method in Java to extract the prefix of an address (as an integer) given a string representing a CIDR notation in the form x.y.z.t/n. Ion channel. Which group of fibers spreads impulses at up to 1 meter per second? ________. The refractory phase is a brief period after the successful transmission of a nerve impulse. The action potential will move down the axon toward the synapse like a wave would move along the surface of the water. During this period, the membrane prepares itself for the conduction of the second stimulus after restoring the original resting state. Nerve cell adhesion molecules (N-CAMs) ________. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. True or False, Acetylcholine is not a biogenic amine. neuron cannot respond to a second stimulus, no matter how strong. Neurons help in transmitting signals in the form of a nerve impulse from the Central nervous system to the peripheral body parts. Two factors are essential for the release of the neurotransmitter from the presynaptic terminal: (1) depolarization of the terminal and (2) the presence of calcium ions (Ca2+) in the extracellular fluid. Schwann cells are functionally similar to ________. A series of EPPs, or a number of them stimulated simultaneously at many synapses, can then bring the cell to the threshold of the action potential. D) the membrane potential has been reestablished. Which result of the stimulus applied is the likely cause of the Transmission of information in the nervous system, Active transport: the sodium-potassium pump, Evolution and development of the nervous system, Transmission in the neuron: Localized potential. Which of the following is not a chemical class of neurotransmitters? D) Group C fibers are not capable of saltatory conduction. However, most synapses are chemical synapses. the neuron cannot respond to a second stimulus, no matter how strong: absolute refractory period: . Which ion channel opens in response to a change in membrane potential and participates in the generation and conduction of action potentials? The greater the influx of positive chargeand, consequently, depolarization of the membranethe higher the grade. Until potassium channels close, the number of potassium ions that have moved across the membrane is enough to restore the initial polarized potential state. This area is called the synaptic cleft. During the refractory period, another action potential cannot be generated. This makes the process of nerve impulse faster as the nerve impulse does not travel the entire length of the axon ( this happens in case of continuous conduction). C) control the chemical environment around neurons, D) guide the migration of young neurons, synapse formation, and other types of channels and can fire multiple action potentials to The threshold stimulus must be strong enough to change the resting membrane potential into action membrane potential. True or False, Myelination of the nerve fibers in the central nervous system is the job of the oligodendrocyte. The substance released at axon terminals to propagate a nervous impulse is called a(n) ________. This period occurs at the end of action potential and limits the speed at which nerve impulses can be generated in a nerve fibre. When one or more presynaptic neurons fire in rapid order it produces a much greater depolarization of the postsynaptic membrane than would result from a single EPSP; this event is called ________ summation. As the flow of current in a wire occurs at a specific voltage only, similarly the conduction of nerve impulse occurs when a stimulus has a maximum threshold value of -55 millivolts. What is the role of acetylcholinesterase? ii. Nerve cell adhesion molecules (N-CAMs) ________. Because the neurotransmitter chemicals are packed into separate, almost identically sized vesicles, their release into the synaptic cleft is said to be quantalthat is, they are expelled in parcels, each vesicle adding its contents incrementally to the contents released from other parcels. ________ is a disease that gradually destroys the myelin sheaths of neurons in the CNS, particularly in young adults. B) the impulse would spread bidirectionally. conduction velocity, Human Anatomy and Physiology, Books a la Carte Edition. Which of the following neurotransmitters inhibits pain and is mimicked by morphine, heroin, and methadone? Plasma serotonin C) nitric oxide D) endorphin, A neuron that has as its primary function the job of connecting other A second nerve impulse cannot be generated until _____. Both a nerve impulse and a lightning strike occur because of differences in electrical charge, and both result in an electric current. In chemical synapses, the conduction of nerve impulse occurs through chemical signals. (In reference to the neuromuscular synapse, it is called the end-plate potential, or EPP.). What generally determines the effects of a neurotransmitter on a postsynaptic cell? This amazing cloud-to-surface lightning occurred when a difference in electrical charge built up in a cloud relative to the ground. In order a nerve impulse to be generated there needs to be a stimulus. During polarization, the membrane is in a resting potential state. concentrated at the nodes of Ranvier. Which of the following is an excitatory neurotransmitter secreted by motor neurons innervating skeletal muscle? The answer involves ions, which are electrically charged atoms or molecules. A stimulus would be you burning your finger or bumping your arm. 0.80.80.8 liters This process is called repolarization. A neuronal circuit that concentrates or directs a large number of incoming impulses to a rather small number of neurons is called a(n) ________. This results in a huge influx of sodium ions inside the cells which trigger the nerve impulse conduction. True or False, A positive feedback cycle is the main force in the generation of graded potentials at receptor ends. 50. central processes. This is because The frequencies of the alleles A and a are 0.60.60.6 and 0.40.40.4, respectively, in a particular plant population. c) stimulate the production of acetylcholine You can specify conditions of storing and accessing cookies in your browser, A second nerve impulse cannot be generated until ________. destroy ACh a brief period after its release by the axon endings. The role of acetylcholinesterase is to ________. Neurons sense the changes in the environment and as a result, generate nerve impulses to prepare the body against those changes. 1.) In electrical synapses, two neurons are connected through channel proteins for transmitting a nerve impulse. When a neuron is not actively transmitting a nerve impulse, it is in a resting state, ready to transmit a nerve impulse. Similarly, in the case of nerve impulse conduction, the neurons the stimulus must have a threshold value for causing the movement of ions across the length of axon (for conducting nerve impulse) by opening the voltage-gated ion channels. 6.) This method of transmitting nerve impulses, while far less common than chemical transmission, occurs in the nervous systems of invertebrates and lower vertebrates, as well as in the central nervous systems of some mammals. Ca2+ is known to be sequestered by certain organelles within the terminal, including the endoplasmic reticulum. The neurons are said to be in resting phase when there is no nerve impulse. Ciliated CNS neuroglia that play an active role in moving the cerebrospinal fluid are called ________. If you consider the axon as an electrical wire or loop, nerve impulse that travels along the axon as current, and the charged particles ( sodium and potassium ions) as the electron particles then the process can be understood quite easily. These differences in concentration create an electrical gradient across the cell membrane, called resting potential. B) destroy ACh a brief period after its release by the axon endings. ________ law is the relationship between voltage, current, and resistance. Postsynaptic membrane. The term central nervous system refers to the ________. All of the following are true of graded potentials except that they ________. The action potential travels along the entire length of the axon. The nerve impulse travels across the membrane of the axon in the form of an electrical signal. True or False, In myelinated axons the voltage-regulated sodium channels are concentrated at the nodes of Ranvier. The transmission of a nerve impulse from one neuron to another neuron is achieved by a synaptic connection (synapse) between them. spinal cord? directly from one neuron to another. At the neuromuscular junction, brief depolarizations measuring no more than one millivolt can be observed in the postsynaptic muscle membrane, even when it is at rest. This threshold potential varies but is generally about 15 millivolts (mV) more positive than the cell's resting membrane potential. C) Spinal reflexes are an example of serial processing. Exactly which ions now permeate the membrane vary according to the neurotransmitters and their receptors (see the section Neurotransmitters and neuromodulators), but the net result of a change in ion diffusion is a change in electrical potential across the membrane. The generation of a second action in some neurons can only happen after a refractory period, when the membrane potential has returned it's base level or even more . The resting membrane potential refers to the non-excited state of the nerve cell at rest when no nerve impulse is being conducted. second nerve impulse CANNOT be generated until membrane potential has been reestablished 29 interior surface of a cell membrane of a resting (nonconducting) neuron differ from the external environment? Between these myelinated sheaths, unmyelinated gaps are presently known as the nodes of Ranvier. What is the role of acetylcholinesterase? c) voltage-gated channel Sodium is the principal ion in the fluid outside of cells, and potassium is the principal ion in the fluid inside of cells. A neurotransmitter might excite one set of target cells, inhibit others, and have complex modulatory effects on still others, depending on the type of receptors. Chapter 11 Fundamentals of the Nervous System and - FreezingBlue Which of the following describes the nervous system integrative function? d) oligodendrocytes, David N. Shier, Jackie L. Butler, Ricki Lewis, Charles Welsh, Cynthia Prentice-Craver, David Shier, Jackie Butler, Ricki Lewis, Human Anatomy and Physiology Laboratory Manual (Main Version). Quiz #11 (Nervous Tissue) Flashcards | Chegg.com As a result of the opening of potassium voltage-gated channels, sodium voltage-gated channels will be closed. (nonconducting) neuron differ from the external environment? to another stimulus is the ________.A) depolarization, Strong stimuli cause the amplitude of action potentials generated to increase. The action potential is +40 mV. C) The synaptic cleft prevents an impulse from being transmitted second nerve impulse cannot be generated until proteins have been resynthesized the na ions DismissTry Ask an Expert Ask an Expert Sign inRegister Sign inRegister Home Neuroglia that control the chemical environment around neurons by buffering potassium and recapturing neurotransmitters are ________. At the threshold, voltage-dependent sodium channels become fully activated, and Na+ pours into the cell. Tightly controlling membrane resting potential is critical for the transmission of nerve impulses. A second nerve impulse cannot phase labeled D? The transmembrane movement of ions is actually carried out by molecular mechanismspecifically, by protein molecules embedded in the lipid layers. Particularly the ions included in this process are sodium and potassium ions. In chemical transmission, a chemical substance called the neurotransmitter passes from one cell to the other, stimulating the second cell to generate its own action potential. 16. a) destroy ACh a brief period after its release by the axon endings Relative refractory period An exceptionally strong stimulus can trigger a response Repolarization The specific period during which potassium ions diffuse out of the neuron due to a change in membrane permeability. A second nerve impulse cannot be generated until ________. An impulse from one nerve cell is communicated to another nerve cell via the ________. When a stimulus is applied to resting membrane, sodium ions freely pass inside the cell and membrane is now said to be in depolarized phase. Which neuron would connect to a muscle? myelin sheath Which ion channel opens in response to a change in membrane potential and participates in generation and conduction of action potentials?
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