Exam 4: Principles of Neural and Hormonal Communication

Local current flows locally between active and adjacent inactive areas of the cell membrane, thereby decreasing the potential in the inactive area to threshold.

Complete each of the following statments. One presynaptic neuron can only produce ____________________ summation on a postsynaptic neuron.

Complete each of the following statments. ____________________-soluble hormones must use ____________________ systems to exert their effects on target cells.

A stimulus that is too weak to depolarize the membrane to threshold produces an action potential that is weaker than normal.

A change in a membrane potential from +30 mV to -70 mV is an example of

With presynaptic inhibition:

Classical neurotransmitters and neuropeptides are sometimes co-secreted from the same axon terminal.

Action potentials may result from hyperpolarization or depolarization.

Complete each of the following statments. Opening a chemically-gated ____________________ channel or ____________________ channel will increase the membrane potential of a plasma membrane.

Complete each of the following statments. ____________________ are chemical messengers that do not cause the formation of EPSPs or IPSPs but rather bring about long-term changes that depress or enhance the action of the synapse.

For the following questions, assume a hypothetical postsynaptic neuron has three presynaptic inputs: neurons X, Y, and Z. Also, assume neuron Z is excitatory. If neurotransmitter from Y causes the membrane potential of the postsynaptic cell to decrease slightly, then the

Complete each of the following statments. At the end of repolarization, the newly opened channels for ____________________ ions close.

After an action potential has occurred, there is more Na⁺ inside the cell than outside the cell (before any Na⁺-K⁺ pump activity has taken place).

Complete each of the following statments. The neuronal relationship where many presynaptic cells terminate on a single postsynaptic cell is called ____________________.

Select the first step for synaptic signaling when the action potential arrives at the axon terminal of a presynaptic neuron.

At the peak of an action potential:

Action potentials can be summed.

Complete each of the following statments. ____________________ is a second messenger formed when a membrane enzyme called a cyclase becomes activated by a G protein.

The period following an action potential during which a membrane cannot experience another action potential

Temporal summation on a postsynaptic neuron takes place when