Question

Graded potentials may

A) initiate an action potential.
B) depolarize the membrane to the threshold voltage.
C) hyperpolarize the membrane.
D) be called EPSPs or IPSPs.
E) All of the above are true.

Answer 1

Graded potentials can depolarize or hyperpolarize a neuron's membrane and if they bring the membrane to the threshold voltage, they can initiate an action potential. They occur as a result of different stimuli and ion channel activities, and when occurring at synapses, are known as EPSPs or IPSPs.

Step-by-step explanation:

Graded potentials are temporary changes in the membrane potential that can have variable effects, depending on the type of stimulus and ion channels involved. These potentials can either depolarize or hyperpolarize the membrane. Depolarizing graded potentials may result from Na+ or Ca2+ entering the cell, making the inside less negative, while hyperpolarizing graded potentials can occur due to K+ leaving the cell or Cl- entering, making the inside more negative. If these changes are sufficient to depolarize the membrane to the threshold voltage, an action potential can be initiated.

Graded potentials can summate and may reach a threshold that results in an action potential if the combined graded potentials are positive, such as a change from -70 mV to -55 mV. They are often associated with the dendrites of neurons and can also be synaptic, being classified as excitatory postsynaptic potentials (EPSPs) or inhibitory postsynaptic potentials (IPSPs) when they occur at synapses.