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.
Want to see the full answer?
Check out a sample textbook solutionChapter 8 Solutions
HUMAN PHYSIOLOGY: AN INTEG ACCESS C
- 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_forwardThe normal concentrations for intracellular and extracellular potassium in a neuron are [K+]in = 150 mM and [K+]out = 5 mM, respectively. Due to an electrolyte imbalance, a patient has the following intracellular and extracellular concentrations of potassium: [K+]in = 140 mM and [K+]out =2 mM. Using the Nernst equation (Chapter 4), calculate the equilibrium potential for potassium in the cells with normal K+ distributions and of the diseased patient. Refer back to Question #1. Will it be easier or more difficult to generate an action potential in the diseased neuron as compared to the normal neuron? Why?arrow_forwardIf: membrane potential=-70mV, ENa=+60mV, and Ex=-90mV, consider which directions Na+ and K+ will leak across the membrane. If both ions are crossing the membrane, what is the most important factor in determining whether membrane potential will become more positive or more negative?arrow_forward
- Intracellular potentials are on the order of -100mV, whereas extracellular potentials are OmV. Assuming these values, answer the following questions. (a) What is the electric potential energy of a chloride ion (CI-) inside a cell? (b) What about outside the cell? (c) What is the probability of finding a Cl- inside the cell relative to finding it outside the cell? Assume that T=310K. P(inside) P(outside) (d) If the concentration of Cl- outside the cell is 100mM, what is the expected concentration inside the cell?arrow_forwardwhich of the following would be true (more than one can be true)? a) summation of A and X would reach threshold b) summation of C and A would be a graded potential c) stimulation by A would depolarize cell d) stimulation by B would be a subthreshold depolarization e) summation of B and C would be a graded potential with the net value of 12 mV depolarizationarrow_forwardHyperkalemia is a condition by which ECF potassium levels become too high (usually due to kidney failure). Consider the following questions about the consequence of hyperkalemia on membrane potential. How would hyperkalemia affect EK? Considering your answer to the previous question, how would hyperkalemia affect membrane potential?arrow_forward
- What is the equilibrium membrane potential due to Na+ ions if the extracellular concentration of Na+ ions is 154 mM and the intracellular concentration of Na+ ions is 23 mM at 20 ∘C ?arrow_forwardAssume that in a neuron, the plasma membrane permeability values for potassium (K+), sodium (Na+), and Cl− are the following: PK = 1, PNa = 12, and PCl = 0.5. Based on physiological concentrations of K+, Na+, and Cl− (refer to the table), determine the membrane potential in this neuron.arrow_forwardMatch each type of membrane potential (resting, threshold, graded, or action) to its definition: a) The membrane potential at which voltage gated sodium channels open. b) The membrane potential that triggers the action potential. c) Change in membrane potential that may or may not reach threshold and that may be depolarizing or hyperpolarizing. d) Rapid, strong depolarization followed by immediate repolarization. This potential is self-renewing if the right ion channels are nearby.arrow_forward
- a)The distribution of sodium ions across the cell membrane of a neuron is 20 mmol/L inside the cell and 200 mmol/L outside the cell. When the system reaches equilibrium, the concentration of sodium ions will be identical on both sides of the cell membrane. What is the standard Gibbs energy difference in the system? Assume the system is at body temperature (37 °C). b)What is the Gibbs energy difference across the membrane in the initial state (prior to reaching equilibrium)?arrow_forwardWhat is the equilibrium membrane potential due to Na+ ions if the extracellular concentration of Na+ ions is 154 mM and the intracellular concentration of Na+ ions is 23 mM at 20 ∘C ?arrow_forwardThe extracellular sodium [Na+]0 is reduced in the saline bath. Following another current injection in a neuron, the membrane potential changes were recorded. a) Why has the membrane potential changed following the Na+ reduction? b) Why has the current injection produced no action potentials? c) How might you experimentally rescue action potential generation?arrow_forward
- Human Physiology: From Cells to Systems (MindTap ...BiologyISBN:9781285866932Author:Lauralee SherwoodPublisher:Cengage Learning