BIOLOGY:THE ESSENTIALS (LL) W/CONNECT
3rd Edition
ISBN: 9781260670929
Author: Hoefnagels
Publisher: MCG CUSTOM
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Chapter 24, Problem 2MCQ
Summary Introduction
Introduction:
An action potential is a brief change in the membrane potential that spreads like a wave along the membrane of an axon. The action potential occurs once the threshold potential of the cell is reached.
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What membrane protein of the neuron is responsible for briefly increasing the Na+ permeability of the membrane during the rising phase of the nerve impulse?
a. the sodium-potassium pump
b. the voltage gated potassium channel
c. the voltage gated sodium channel
d. the stimulus gated sodium channel
e. the ligand gated ion channel
The nerve impulses always travel in one direction from dendrites to axon terminals. What prevents an action potential from travelling backward?
a. Hyperpolarization of the neuron makes the membrane more positive and prevents another action potential.
b. After repolarization, the refractory period occurs, where the sodium ions are found outside the cell.
c. After repolarization, the reversal of ions prevents another action potential as there would not be enough sodium ions outside the cell to rush in.
d. The refractory period prevents another action potential by lowering the threshold potential.
Both potassium and sodium channels located along the nerve membrane are voltage-gated. This means that they respond to the changes in the voltage by opening and closing the gates to allow the ions to flow in or out of the membrane.
When the threshold level is reached and depolarization occurs, how come only the sodium ions begin to rush in?
a. The threshold levels for both sodium and potassium channels are equal, but sodium channels are slower to open.
b. The threshold levels for both sodium and potassium channels are equal, but potassium channels take longer to open.
c. The threshold level for the potassium channels is lower than the sodium channels.
d. The threshold level for the potassium channels is higher than the sodium channels.
Chapter 24 Solutions
BIOLOGY:THE ESSENTIALS (LL) W/CONNECT
Ch. 24.1 - Prob. 1MCCh. 24.1 - Prob. 2MCCh. 24.1 - Distinguish between the central and peripheral...Ch. 24.2 - Describe the parts of a typical neuron.Ch. 24.2 - Prob. 2MCCh. 24.2 - Prob. 3MCCh. 24.3 - Prob. 1MCCh. 24.3 - How does an axon generate and transmit a neural...Ch. 24.3 - Prob. 3MCCh. 24.4 - Describe the structure of a synapse.
Ch. 24.4 - Prob. 2MCCh. 24.4 - Prob. 3MCCh. 24.5 - Prob. 1MCCh. 24.5 - How do the sensory and motor pathways of the...Ch. 24.5 - Prob. 3MCCh. 24.5 - Prob. 4MCCh. 24.6 - Prob. 1MCCh. 24.6 - What are the major structures in the hindbrain,...Ch. 24.6 - Prob. 3MCCh. 24.6 - Prob. 4MCCh. 24.6 - Prob. 5MCCh. 24.7 - Prob. 1MCCh. 24.7 - Prob. 2MCCh. 24.7 - What are the major types of sensory receptors?Ch. 24.7 - Prob. 4MCCh. 24.7 - What is sensory adaptation, and how is it...Ch. 24.8 - Prob. 1MCCh. 24.8 - Prob. 2MCCh. 24.9 - Prob. 1MCCh. 24.9 - Prob. 2MCCh. 24.9 - Prob. 3MCCh. 24.10 - Prob. 1MCCh. 24.10 - Prob. 2MCCh. 24.10 - Prob. 3MCCh. 24.11 - What is the role of mechanoreceptors in the sense...Ch. 24.11 - Prob. 2MCCh. 24 - Prob. 1MCQCh. 24 - Prob. 2MCQCh. 24 - Prob. 3MCQCh. 24 - Prob. 4MCQCh. 24 - Prob. 5MCQCh. 24 - In what way are the senses of smell and taste...Ch. 24 - Prob. 1WIOCh. 24 - Prob. 2WIOCh. 24 - Prob. 3WIOCh. 24 - Prob. 4WIOCh. 24 - How does myelin alter the conduction of a neural...Ch. 24 - Prob. 6WIOCh. 24 - Prob. 7WIOCh. 24 - Prob. 8WIOCh. 24 - Prob. 9WIOCh. 24 - Prob. 10WIOCh. 24 - Prob. 1SLCh. 24 - Prob. 1PITCh. 24 - Prob. 2PITCh. 24 - Prob. 3PIT
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- A channel opens on a postsynaptic membrane that causes a negative ion to leave the cell. What type of graded potential is this? a. depolarizing b. repolarizing c. hyperpolarizing d. non-polarizingarrow_forwardDuring the rising portion of the action potential, which ions are moving across the membrane and in which direction? A. Sodium ions move out. B. Sodium ions move in. C. Both sodium and potassium ions move in. D. Potassium ions move in.arrow_forwardAfter the action potential reaches its peak, the potential across the membrane falls toward its resting level. What accounts for this recovery? a. The sodium–potassium pump removes the extra sodium. b. Potassium ions move out because their channels are open and the electrical gradient pushes them out. c. Potassium ions move out because their channels are open and the concentration gradient pushes them out. d. Potassium ions move in.arrow_forward
- Lidocaine is an anesthetic that is used to prevent the propagation of action potentials. Which compartment would lidocaine MOST likely target? A. axon B. dendrite C. soma D. synaptic cleftarrow_forwardIn an experiment you place a neuron and its synaptic contacts into a medium containing no calcium ions. You stimulate the neuron causing an action potential to propagate down the axon into the axon terminal of the neuron. 3.) What is the most likely result of this experimental manipulation? A. Prolong the refractory period of the action potential B. Decrease the time required to move sodium ions out of the axon terminal C. Prevent neurotransmitter from binding to receptors on postsynaptic cells D. Enhance the voltage changes associated with the action potential E. Prevent release of neurotransmitter into the synapsearrow_forwardDuring an action potential, the inside of the cell membrane becomes more positive than the outside. Why does this happen? a. During depolarization, the sodium ions rush in and the potassium ions have not begun rushing out, making the inside more positive. b. During depolarization, the sodium ions rush in and the potassium ions have not begun rushing out, making the outside more positive. c. During depolarization, the potassium ions rush in and the sodium ions have begun rushing out, making the inside more positive. d. During depolarization, the sodium ions rush in and the potassium ions have begun rushing out, making the outside more positive.arrow_forward
- Voltage-gated Na+ channels open upon reaching what state? a. resting potential b. threshold c. repolarization d. overshootarrow_forwardDepolarization and repolarization changes that occur during the action potential are produced by a. Negative feedback loops b. Channel mediated transport c. Simple diffusion of ions down their concentration gradient d. Active transport pumps along the neuron membranearrow_forwardThe figure below may help in answering some of the questions. 1. What ions are flowing (and in which direction) both during the rising phase and the falling phase of the action potential? 2. What are the values of both the 'y' (vertical) axis and the 'x' (horizontal) axis. 3. If extracellular levels of K+ rose (a condition called hyperkalemia), how would that affect the resting membrane potential? 3arrow_forward
- Use this illustration to place these events in the order they occur during synaptic communication: Column A Column B a. Voltage gated sodium channels carry the action potential to the synapse by allowing the influx of sodium ions. 1. 1 2 b. An increase in calcium levels triggers vesicle release. 3. 3 c. Sodium enters the post-synaptic cell, causing it to depolarize. 4. 4 d. Sodium influx at the synapse activates voltage gated 5. calcium channels which allow calcium ions to enter the presynaptic neuron. 6. 6. e. Neurotransmitters are released into the synaptic cleft. f. Ligand-gated ion channels are opened by the neurotransmitters. 2.arrow_forwardExamine the graph below, and answer the questions that follow. a. Indicate the specific events that are occurring at 1, 2, 3, and 4. b. At which area of the graph are sodium ions rapidly entering the neuron? c. At which area of the graph are potassium ions rapidly leaving the neuron? At which area of the graph is the sodium ion concentration higher outside than inside the neuron? d. Membrane potential, V (mV) +50- -50- -70- -90- 0 1 1 2 3 Time (ms) 4 5 V₁ Vrest thresholdarrow_forwardA neuron must reach threshold to fire an action potential. In this context, threshold refers to which event? a. voltage at which damage occurs to the membrane because of the electrical charge b. the voltage at which potassium ions begin to flow in and out of the cell c. the voltage at which voltage-gated sodium channels open d. the voltage at which the neuron can no longer produce an action potential According to studies in developing rodents, testosterone treatment causes detectable changes in: a. the sex region Y gene b. the thalamus c. the hypothalamus d. alpha-fetoproteinarrow_forward
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