Concept explainers
(a)
To determine: Whether the neuron will hyperpolarize or depolarize from resting membrane potential of -70 mV if sodium ion enters the cell.
Introduction: Neuron is the structural and functional unit of the nervous system. It can be hyperpolarized or depolarized based on the movement of different ions inside and outside of the cell.
(b)
To determine: Whether the neuron will hyperpolarize or depolarize from resting membrane potential of -70 mV if potassium ion leaves the cell.
Introduction: Neurons help in the generation of action potential and graded potential to transmit the information inside the body; the electrical conductivity of the neuron changes by the inward and outward movement of ions.
(c)
To determine:Whether the neuron will hyperpolarize or depolarize from resting membrane potential of -70 mV if chloride ions enter the cell.
Introduction: Neurons transmit the information from one neuronal cell to the other. The human brain contains millions of neurons.
(d)
To determine: Whether the neuron will hyperpolarize or depolarize from resting membrane potential of -70 mV if calcium ions enter the cell.
Introduction: Neurons can receive or send a message from one part of the body to the other. The electrical conductivity of neurons occurs due to unequal distribution of ions in and out of the cell.
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Human Physiology: An Integrated Approach (8th Edition)
- Conformational changes in channel proteins brought about by voltage changes are responsible for opening and closing Na+ and K+ gates during the generation of an action potential. (True or false?)arrow_forwardAssume 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_forwardIf the postsynaptic cell's plasma membrane were to become substantially more permeable to Na+, you would expect the membrane potential to [depolarize, hyperpolarize] __________________. You would expect the membrane potential to depolarize if the extracellular K+ concentration were to [increase, decrease] ______________. a.) hyperpolarize, decrease b.) depolarize, decrease c.) depolarize, decrease d.) hyperpolarize, increasearrow_forward
- At the peak of an action potential, would the relative permeability of Na be higher than K? Which ion would be the least permeable to the membrane during falling phase?arrow_forwardWhy is the resting membrane potential a negative value? And how do you determine resting membrane potential?arrow_forwardDescribe the contribution of each of the following to the establishment and maintenance of membrane potential: Part A Na+K+ Pump Passive movement of K+ across the membrane Passive movement of Na+ across the membrane Part B Resting membrane potential is approximately -70mV. Explain what resting membrane potential is and what -70mV refers to.arrow_forward
- In an experiment, the extracellular [Na+] surrounding a nerve cell was reduced from 145 to 45 mM. Which of the following is the most likely effect of this on action potentials? No action potentials would occur because the concentration of extracellular Na+ is too low. The membrane potential would become more negative so the threshold for action potential generation could not be reached. The nerve cell would still produce an action potential but its amplitude would be reduced and the depolarisation phase would be slower. The nerve cell would still produce an action potential but its amplitude would be reduced and the depolarization phase would be more rapid.arrow_forwardIf a postsynaptic cell has synapses from five different cells, and three cause EPSPs and two of them cause IPSPs, give an example of a series of depolarizations and hyperpolarizations that would result in the neuron reaching threshold.arrow_forwardList three ways in which action potentials can be initiated in neurons?arrow_forward
- Human Physiology: From Cells to Systems (MindTap ...BiologyISBN:9781285866932Author:Lauralee SherwoodPublisher:Cengage Learning