In: Anatomy and Physiology
Animal Physiology Question
1. Contrast ionotropic and metabotropic receptors. Specifically describe how they differ in their mechanisms of converting a sensory stimulus to a change in membrane potential. Provide one example of an ionotropic receptor we discussed in class and briefly describe how it works. Provide one example of a metabotropic receptor discussed in the textbook and briefly describe how it works.
Ionotropic receptors are ligand gated receptors. The binding of ligand to the receptor changes the shape of the receptor and opens channels for the ions to enter the cells and thus change the membrane potential.
When a neurotransmitter binds on metabotropic receptor it uses a second messenger to open the associated ionic channels. The difference is that it needs a second messenger and doesn't Bhave its own channels to open.
Nicotinic Ach receptor is an example for ionotropic receptor. The binding of the neurotra acetylcholine to the receptor cause the receptor to change the shape this leads the opening of the Na+ channels. The influx of Na+ ions creates more positive charge inside the cell and leads to change in membrane potential.
Muscarinic ACH receptor is an example for metabotropic receptor. The binding of ACH to muscranic receptor activates the G protein. The G protein alpha unit thus activate the intracellular messenger and leads to the opening of associated k+ channel and leads to the efflux of K+ ions. This changing the membrane potential during hyper polarisation.