What is meant by the term "chemically gated sodium channel"? Group of answer choices A membrane channel that opens when some chemical binds to it, allowing sodium to cross the cell membrane A membrane channel that opens when sodium binds to it, allowing neurotransmitter to enter a cell A membrane pump that moves 3 sodium ions out of the cell using ATP A membrane channel that opens when sodium binds to it, allowing potassium to leave the cell.

A membrane channel that opens when some chemical binds to it, allowing sodium to cross the cell membrane

Explanation:

Channels are integral membrane proteins that are involved in facilitated diffusion of specific, small, inorganic ions across the membrane. A chemically gated channel is also known as a ligand-gated channel. These channels open and close in response to the binding of a chemical or ligand. Here, the ligand serves as a stimulus to trigger the opening and closing of the channels. A chemically gated sodium channel would open and close when a specific ligand binds to it. Some of the examples of ligands are hormones, neurotransmitters, ions, etc.

A membrane channel that opens when some chemical binds to it, allowing sodium to cross the cell

Explanation:

Chemically gated sodium channels are transmembrane channel proteins which let sodium ion pass through the membrane when a ligand like a neurotransmitter binds to it.

On exciting a presynaptic neuron, it releases neurotransmitter from vesicles into synaptic cleft. The neurotransmitter binds to receptors present on post synaptic neuron. If the receptors are chemically gated channels, they undergo a confirmational change due to which they open. The ions can then flow across these channels.

The channels are made of at least two domains. There is a transmembrane domain containing a pore through which ions can pass through. There is also an extracellular domain which binds to the ligand.