Cholinergic nicotinic receptors are a type of neurotransmitter receptor that is activated by the neurotransmitter acetylcholine. These receptors are found in many different parts of the body and play a role in a wide range of physiological functions. However, there are a few places where you would not find cholinergic nicotinic receptors.
One place you would not find cholinergic nicotinic receptors is in the central nervous system (CNS). While acetylcholine is an important neurotransmitter in the CNS, it acts on a different type of receptor called the cholinergic muscarinic receptor. Cholinergic nicotinic receptors are mostly found in the peripheral nervous system, including the autonomic nervous system, which controls unconscious bodily functions such as heart rate, digestion, and respiration.
Another place you would not find cholinergic nicotinic receptors is in the smooth muscle cells of the body. While acetylcholine can stimulate smooth muscle contraction, it does so through the action of muscarinic receptors. Nicotinic receptors are not found in smooth muscle tissue.
Finally, you would not find cholinergic nicotinic receptors in the liver or other internal organs. These receptors are mostly found in the nervous system and in certain types of glandular cells.
In summary, while cholinergic nicotinic receptors are found in many parts of the body, they are not present in the central nervous system, smooth muscle tissue, or in the liver or other internal organs. These receptors play an important role in the functioning of the nervous system and in the regulation of various physiological processes, but their distribution is limited to specific types of cells and tissues.
