Question

. How do graded changes in membrane potential give rise to all-or-none changes that generate action potentials?
a) The membrane recognizes only action potentials generated by positive ions, causing a voltage threshold to be reached.
b) The membrane recognizes only action potentials generated by negative ions, causing a voltage threshold to be reached.
c) Many graded potentials at different points along the membrane are summed, causing the voltage threshold to be reached.
d) Many graded potentials reaching the same point on the membrane are summed, causing the voltage threshold to be reached. e) The membrane allows only voltage-gated channels to open and close, enabling an electrical charge gradient to be created.

Answer 1

The generation of action potential depends upon whether a particular stimulus is able to bring depolarisation to the threshold. So in response to weak depolarisation the action potential is not able to reach its threshold therefore no action potential generates whereas when strong depolarisation is able to reached to the threshold the action potential is able to generate. As in graded potential which give rise to change in the potential that varies in the magnitudes. Thus, many excitatory graded potentials have to happen at once to depolarize the cell body enough to trigger the action potential.