Which of the following is (are) true of ligand-gated ion channels?

Answer:

The properties of ligand-gated ion channels include:

a. They play a crucial role in the nervous system by altering sodium and calcium levels within cells.  

b. Their significance is primarily linked to the nervous system.

c. They are vital for the nervous system, responsible for modulating sodium and calcium levels in cells, and they respond to chemical signals by either opening or closing.

Explanation:

Ligand-gated ion channels (LICs or LGICs), often called ionotropic receptors, represent a class of trans-membrane ion-channel proteins that open to permit the flow of ions like Na+, K+, Ca2+, and/or Cl− across membranes in reaction to the binding of chemical signals. Their function contrasts with that of voltage-gated ion channels, which are triggered by changes in voltage across membranes (i.e., when depolarization occurs) and are responsive to membrane potentials. In comparison to GPCRs that utilize secondary messengers, ligand-gated channels operate upon the binding of a ligand (a specific chemical signal). Both types of channels are essential for the effective activation of the post-synaptic neuron.