Assume a Hypothetical Postsynaptic Neuron Has Three Presynaptic Inputs, X

question 155

Multiple Choice

Assume a hypothetical postsynaptic neuron has three presynaptic inputs, X, Y, and Z. When presynaptic neurons X and Y are stimulated simultaneously, the postsynaptic neuron reaches threshold and undergoes an action potential; yet, when presynaptic neurons X and Z are stimulated simultaneously, there is no change in potential of the postsynaptic neuron. Which of these statements correctly describes the presynaptic neurons Y and Z?

• A)Presynaptic neurons Y and Z are both excitatory.
• B)Presynaptic neurons Y and Z are both inhibitory.
• C) Presynaptic neuron Y is excitatory, and presynaptic neuron Z is inhibitory.
• D) Presynaptic neuron Y is inhibitory, and presynaptic neuron Z is excitatory.

---

Definitions:

Lymphocytes

A subtype of white blood cells involved in the immune response, including B cells, T cells, and natural killer cells.

Major Histocompatibility Complexes

A set of cell surface proteins important for the immune system to recognize foreign molecules, playing a critical role in antigen presentation.

T-cell Receptors

Molecules found on the surface of T-cells that are responsible for recognizing fragments of antigen as peptides bound to major histocompatibility complex (MHC) molecules.

Foreign Antigens

Substances that are recognized by the immune system as non-self, triggering an immune response.