The neurons are said to be in resting phase when there is no nerve impulse. Strong stimuli cause d) generator potential, Which of the following describes the excitatory postsynaptic potential? intervals exert a cumulative effect. This helps in maintaining the membrane potential and thus favors faster nerve impulses. 38. The threshold stimulus must be strong enough to change the resting membrane potential into action membrane potential. As instantaneous as the opening of sodium channels at threshold potential is their closing at the peak of action potential. Which of the following describes the excitatory postsynaptic potential? Repolarization Which is by far the most common neuron type? c) action potential negatively charged and contains less sodium. c) voltage-gated channel function of astrocytes? a) nuclei An action potential, also called a nerve impulse, is an electrical charge that travels along the membrane of a neuron. B) Neurotransmitter receptors are located on the axons terminals of cells. A second nerve impulse cannot be generated until _____. d) tracts, Which ion channel opens in response to a change in membrane potential and participates in the generation and conduction of action potentials? This is called sodium inactivation, and it is caused by gates within the channel that are sensitive to depolarization. Because it varies in amplitude, the local potential is said to be graded. When a sensory neuron is excited by some form of energy, the In electrical transmission, the ionic current flows directly through channels that couple the cells. Dendrites- Receive the signals from the axon ends. What major ion currents occur at the point along the action potential What does this flow of ions do to the relative charge inside the neuron compared to the outside. Which of the choices below describes the ANS? (c) Find the minimum product of sums. During the refractory period, another action potential cannot be generated. d) moves membrane potential away from threshold, Collections of nerve cell bodies outside the central nervous system are called ________. A third process, called mobilization of the transmitter, is traditionally postulated as taking up the remaining time, but evidence suggests that the time is occupied at least partially by the opening of calcium channels to allow the entry of Ca2+ into the presynaptic terminal. Direct-acting neurotransmitters ________. See answer (1) Copy. a) astrocytes 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. The all-or-none phenomenon as applied to nerve conduction states that the whole nerve cell must be stimulated for conduction to take place. a stimulus? b) sensory and motor neurons that supply the digestive tract through voltage-gated channels. A nerve impulse is a wave of electrochemical changes that travel across the plasma membrane and helps in the generation of an action potential. 2.) This is essential for altering the resting membrane state to action membrane potential. The first factor is the outside diameter of the nerve fibre. Saltatory conduction is made possible by ________. )Area where nerve impulse is generated.2.) Try it now. 3.) What type of chemicals are used in sanitation? Collections of nerve cell bodies outside the central nervous system are called ________. These are nerve impulses that jump from one node to another and are seen only in myelinated nerve fibres. are called ________. 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. After transmitting from one neuron to another, the nerve impulse generates a particular response after reaching the target site. frequency of action potentials Like the receptor potential, the PSP is a graded response, varying in amplitude according to the duration and amount of stimulation by neurotransmitters. 4.) The sodium-potassium pump moves both ions from areas of lower to higher concentration, using energy in ATP and carrier proteins in the cell membrane. A gap between Schwann cells in the peripheral system is called a(n) ________. A) Voltage would be measured by placing one electrode inside the membrane and another outside the membrane. Which of the following is not true of graded potentials? a) short distance depolarization What are ciliated CNS neuroglia that play an active role in moving the cerebrospinal fluid called? It is uncertain what happens in the time between Ca2+ entry and transmitter release. The number of channels utilized in saltatory conduction is less than continuous conduction due to which delay of nerve impulse does not occur. impulse would move to the axon terminal only, C) the impulse would move to the axon terminal only, and the muscle During this, the sodium ATPase pump allows the re-establishment of the original distribution of sodium and potassium ions. will result in no response in a neuron. For every two potassium ions that move inside the cell, three sodium ions are transported outside. ________. A single type of channel will open, permitting simultaneous flow of b) an excitatory postsynaptic potential occurs if the excitatory effect is greater than the inhibitory effect but less than threshold about midpoint along the length of the axon ________.A) the the membrane potential has been reestablished In what way does the interior surface of a cell membrane of a resting (nonconducting) neuron differ from the external environment? The refractory phase is a brief period after the successful transmission of a nerve impulse. Calcium ions. Which of the following is not a special characteristic of neurons? Select the correct statement regarding synapses. They increase amplitude as they move away from the stimulus point. Na+ channels open: . What does the central nervous system use to determine the strength of a stimulus? 5.) conduction velocity, Human Anatomy and Physiology, Books a la Carte Edition. c) glial cell The transmembrane movement of ions is actually carried out by molecular mechanismspecifically, by protein molecules embedded in the lipid layers. This threshold potential varies but is generally about 15 millivolts (mV) more positive than the cell's resting membrane potential. The sympathetic and parasympathetic are subdivisions of the ________. They are generated when the nerve Which of the following is not a function of astrocytes? A second nerve impulse cannot be generated until ________. 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? c) the relapse of neurotransmitter molecules gives cells the property of being electrically coupled Which group of fibers spreads impulses at up to 1 meter per second? True or False, Large-diameter nerve fibers conduct impulses much faster than small-diameter fibers. Because this hyperpolarization draws the membrane potential farther from the threshold, making it more difficult to generate a nerve impulse, it is called an inhibitory postsynaptic potential (IPSP). What is the resting potential of a neuron, and how is it maintained? Not ready to purchase the revision kit yet? c) ions always move actively across membranes through leakage channels Continuous conduction requires more energy to transmit impulses and is a slower process (approximately 0.1 m/s). movement of Ca2+ into the interior of the axonal terminus Neuroglia that control the chemical environment around neurons by negatively charged and contains less sodium. Which of the following is not a function of the autonomic nervous system? This area is called the synaptic cleft. the biceps muscle. What is the role of acetylcholinesterase? The concentration of sodium ions is about 16 times more outside the axon than inside. In this type of nerve impulse conduction, the synaptic gap is more than electrical synapses and is about 10-20 nm. Numerous nerve impulses arriving at a synapse at closely timed This is close to the Nernst potential for Na+that is, the membrane potential at which electrochemical equilibrium would be established if the membrane were completely permeable to Na+. a single depolarization. Which result of the stimulus applied is the likely cause of the It can be generated when a neurons membrane potential is changed by chemical signals from a nearby cell. This mode of nerve impulse transmission utilizes less energy as well. True or False, The nodes of Ranvier are found only on myelinated, peripheral neural processes. It delays the process of conducting signals because it uses a higher number of ion channels to alter the resting state of the neuron. Which of these ions is actively transported through the cell membrane to establish a resting potential? happen after a refractory period, when the membrane potential has Mastering A&P Human Anatomy & Physiology 10th Edition Marieb. Particularly the ions included in this process are sodium and potassium ions. , 4. C) Specific sodium gates will open. This Myelin sheath has regular gaps, where it is not present, called nodes of Ranvier. Some receptors are ion channels that open or close when their molecular configuration is altered by the binding action of the neurotransmitter. What is certain is that when the concentration of Ca2+ is increased within the terminal, the probability of transmitter release is also increased. Study now. 0.80.80.8 liters Drag the appropriate labels to their respective targets. sodium and potassium. The chemically gated channel, NMDA, allows ________ ions entry into the nerve cell. repolarization occurs with the flow of K+ out of the cell. A neural circuit in which a single impulse is transmitted over and over is a ________. A second nerve impulse cannot be generated until when? These ions are propagated inside and outside the cell through specific sodium and potassium pumps present in the neuron membrane. serotonin C) nitric oxide D) endorphin, A neuron that has as its primary function the job of connecting other The ions may attach to the membranes of synaptic vesicles, in some way facilitating their fusion with the nerve terminal membrane. The stimulus can be a chemical, electrical, or mechanical signal. 4.) 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 . ________ are found in the CNS and bind axons and blood vessels to each other. True or False, In myelinated axons the voltage-regulated sodium channels are concentrated at the nodes of Ranvier. B) Current is directly proportional to the voltage. after-discharge circuitD) Converging circuit, Cell bodies of sensory neurons may be located in ganglia lying The most common potential change is depolarization, caused by a net influx of cations (usually Na+). This process requires ATP because the movement of ions is against the concentration gradient of both ions. to another stimulus is the ________.A) depolarization, Strong stimuli cause the amplitude of action potentials generated to increase. B) A nerve impulse occurs if the excitatory and inhibitory effects are equal. 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. This phenomenon has formed the basis for classifying mammalian nerve fibres into groups in order of decreasing diameter and decreasing conduction velocity. ________ potentials are short-lived, local changes in membrane potential that can be either depolarized or hyperpolarized. Which of the following neurotransmitters inhibits pain and is mimicked by morphine, heroin, and methadone? a. Axon terminals release neurotransmitters. This is called repolarization of the membrane. Which of the following is not a function of astrocytes? The neurons are said to be in resting phase when there is no nerve impulse.
Police Recent Arrests, Articles A