Anatomy & Physiology
1st Edition
ISBN: 9781938168130
Author: Kelly A. Young, James A. Wise, Peter DeSaix, Dean H. Kruse, Brandon Poe, Eddie Johnson, Jody E. Johnson, Oksana Korol, J. Gordon Betts, Mark Womble
Publisher: OpenStax College
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Chapter 12, Problem 7ILQ
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.
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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.
The following table summarizes the characteristics of four different neurons. Based on these characteristics, which of these neurons would most likely have the slowest
conduction velocity?
Neuron
#3
#4
O #1
O #2
#3
O #4
Diameter
(μM)
P
Myelination
no
Explain what happens when an action potential reaches the axon terminus (terminal) by activating the receptors on the postsynaptic membrane.
Explanation addressing the question above
When an action potential, or nerve impulse, arrives at the axon terminal, it activates voltage-gated calcium channels in the cell membrane. Which is present at a much higher concentration outside the neuron than inside, rushes into the cell. The Ca2+ allows synaptic vesicles to fuse with the axon terminal membrane, releasing neurotransmitters into the synaptic cleft. The molecules of neurotransmitters diffuse across the synaptic cleft and bind to receptor proteins on the postsynaptic cell. Activation of postsynaptic receptors leads to the opening or closing of ion channels in the cell membrane. This may be depolarizing, making the inside of the cell more positive, or hyperpolarizing making the inside more negative depending on the ions involved. The excitatory and inhibitory postsynaptic potentials…
Chapter 12 Solutions
Anatomy & Physiology
Ch. 12 - In 2003, the Nobel Prize in Physiology or Medicine...Ch. 12 - Visit this site...Ch. 12 - Visit this site...Ch. 12 - View the University of Michigan Webscope...Ch. 12 - What happens across the membrane of an...Ch. 12 - Visit this site...Ch. 12 - Watch this video...Ch. 12 - Watch this video...Ch. 12 - Which of the following cavities contains a...Ch. 12 - Which structure predominates in the white matter...
Ch. 12 - Which part of a neuron transmits an electrical...Ch. 12 - Which term describes a bundle of axons in the...Ch. 12 - Which functional division of the nervous system...Ch. 12 - What type of glial cell provides myelin for the...Ch. 12 - Which part of a neuron contains the nucleus?...Ch. 12 - Which of the following substances is least able to...Ch. 12 - What type of glial cell is the resident macrophage...Ch. 12 - What two types of macromolecules are the main...Ch. 12 - If a thermoreceptor is sensitive to temperature...Ch. 12 - Which of these locations is where the greatest...Ch. 12 - How long does all the signaling through the...Ch. 12 - What is the target of an upper motor neuron?...Ch. 12 - What ion enters a neuron causing depolarization of...Ch. 12 - Voltage-gated Na+ channels open upon leaching what...Ch. 12 - What does a ligand-gated channel require in order...Ch. 12 - What does a mechanically gated channel respond to?...Ch. 12 - Which of the following voltages would most likely...Ch. 12 - Which of the following is probably going to...Ch. 12 - How much of a change in the membrane potential is...Ch. 12 - A channel opens on a postsynaptic membrane that...Ch. 12 - What neurotransmitter is released at the...Ch. 12 - What type of receptor requires an effector protein...Ch. 12 - Which of the following neurotransmitters is...Ch. 12 - What responses are generated by the nervous system...Ch. 12 - When eating food, what anatomical and functional...Ch. 12 - Multiple sclerosis is a demyelinating disease...Ch. 12 - Which type of neuron, based on its shape, is best...Ch. 12 - Sensory fibers, or pathways, are referred to as...Ch. 12 - If a person has a motor disorder and cannot move...Ch. 12 - What does it mean for an action potential to be an...Ch. 12 - The conscious perception of pain is often delayed...Ch. 12 - If a postsynaptic cell has synapses from five...Ch. 12 - Why is the receptor the important element...
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- Assume presynaptic excitatory neuron A terminates on a postsynaptic cell near the axon hillock and presynaptic excitatory neuron B terminates on the same postsynaptic cell on a dendrite located on the side of the cell body opposite the axon hillock. Explain why rapid firing of presynaptic neuron A could bring the postsynaptic neuron to threshold through temporal summation, thus initiating an action potential, whereas firing of presynaptic neuron B at the same frequency and the same magnitude of EPSPs may not bring the postsynaptic neuron to threshold.arrow_forwardRegardless of type, all neurons transfer signals between each other or to effectors (muscles or glands) at a synapse. The neuromuscular junction that we talked about with the muscular system is one example of a synapse. The diagram below shows the general features of a synapse Match each term or description with the appropriate letter in the diagram. You may use terms more than once. 1. Synaptic knob in axon terminal of pre-synaptic cell: 2. Synaptic cleft: 3. Neurotransmitter: 4. Dendrite of post-synaptic cell: 5. Cell body of post-synaptic cell: 6. Receptor in plasma membrane of post-synaptic cell: 7. Chemical released by neurons that stimulates or inhibits other neurons, muscles, or glands: 8. Cell that sends the signal: 9. Dendrite of cell that receives the signal: 10. Space between cells that must be crossed by neurotransmitters: 11. Structure that opens, like a "protein door", when neurotransmitters attach to it:arrow_forwardIf a neuron is stimulated simultaneously by 2 stimuli at its dendrites (one generates a very large hyperpolarizing potential and the other generates a very small depolarizing potential). What would happen to this neuron? Group of answer choices The summation of these two graded potentials will generate an action potential and this action potential will travel down the axon. Summation of these two graded potentials will cause the membrane potential at the axon hillock to be more negative. These graded potentials will bring the resting membrane potential to 0 mV. These graded potentials with opposite polarity would therefore generate two action potentials and they will travel along this neuron in opposite direction.arrow_forward
- The image attached below depicts a histological slice of human cerebral cortex tissue.Using knowledge of the central nervous system and various cell-cell interactions, identify thekey type(s) of cell junctions present in this image (for example, tight junctions, gap junctions, and adherens junctions/desmosomes). Briefly describe the function of these celljunctions. How would the function of the central nervous system be impaired if your above identified celljunctions were disrupted?arrow_forwardYou are investigating the effects of a newly discovered cell type. You have an intact synapse (including pre- and post-synaptic neurons) in a dish and observe what happens upon electrical stimulation. Following electrical stimulation of the pre-synaptic neuron, you record an action potential in the pre-synaptic neuron and an EPSP in the post-synaptic neuron. The synapse most likely utilizes which of the following neurotransmitters? Sodium (Na++) GABA Calcium (Ca++) Glutamatearrow_forwardRepolarization occurs because Multiple Choice more sodium ions diffuse into the cell than potassium ions diffuse out of it. potassium ions continue to diffuse out of the cell after the inactivation gates of the voltage-gated sodium ion channels begin to close. the increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level. the extra efflux of potassium ions causes the membrane potential to become slightly more positive than the resting value. the inactivation gates of the voltage-gated sodium ion channels begin to open and the diffusion of sodium ions decreases.arrow_forward
- What events in a neuron membrane occur slowly when threshold potential is reached? Opening of K+ channel activation gate Closing of Na+ channel inactivation gate Opening of the Na+ voltage-gated channel activation gate Closing of Cl- voltage gated channels Closing of K+ inactivation gate (More than one answer may be correct, please help in answering)arrow_forwardWhich of the following are the likely explanations for the failure of a postsynaptic neuron to trigger an action potential? Select all that apply. The EPSPs are neutralized by the neurotransmitter The summation of IPSPs and EPSPs is insufficient to depolarize the cell to threshold The synapses generating the EPSPs are too close to the axon hillock The synapses generating the EPSPs are too far from the axon hillockarrow_forwardWhich of the following statements is not true about neurons? When there is no active nerve impulse, the concentration of Na+ ions outside of the cell is greater than inside the cell After a nerve impulse passes a region of the axon, that region will not be able to carry another impulse again for a brief period of time When a nerve impulse occurs, sodium channels in the axon open first, followed by potassium channels The inside of an axon is typically negatively charged compared to the outside of an axon The cell uses energy to actively pump Na+ ions into the axon and K+ ions out of the axon.arrow_forward
- What happens across the membrane of an electrically active cell is a dynamic process that is hard to visualize with static images or through text descriptions. View this animation (http://openstaxcollege.org/l/dynamic1) to learn more about this process. What is the difference between the driving force for Na+ and K+? And what is similar about the movement of these two ions?arrow_forwardA postsynaptic neuron has three presynaptic inputs from neurons X, Y, and Z. When X and Y are stimulated simultaneously and repeatedly, the postsynaptic neuron reaches threshold and undergoes an action potential. When X and Z are stimulated simultaneously, however, there is no change in the membrane potential of the postsynaptic neuron. Which of the following is correct? Select one: A. The simultaneous stimulation of X and Z is an example of temporal summation. O B. The simultaneous stimulation of X and Y is an example of temporal summation. O C. The repeated rapid stimulation of X is an example of spatial summation. O D. The stimulation of Y causes an IPSP in the postsynaptic neuron. O E. The stimulation of Z causes a hyperpolarization in the postsynaptic neuron.arrow_forwardAn action potential is regarded as an example of positive feedback. Which of the following examples below best illustrates the positive feedback aspect of an action potential? Voltage gated potassium ion channels open slowly and remain open long enough to cause hyperpolarization The sodium potassium pump consistently moves ions as long as ATP is available, and regardless of membrane potential changes. A threshold stimulus will cause the opening of voltage gated sodium ion channels that will cause further depolarization by opening still more voltage gated sodium ion channels along the axon.arrow_forward
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