BIO 12D Lecture Notes - Lecture 22: Cardiac Muscle, Brainstem, Nicotinic Acetylcholine Receptor
16 Aug 2020
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Document Summary
The autonomic nervous system uses a variety of chemical signals. The sympathetic and parasympathetic branches can be distinguished by their neurotransmitters and receptors using the following rules. Both sympathetic and parasympathetic preganglionic neurons release acetylcholine (ach) onto nicotinic cholinergic receptors (achr) on the postganglionic cell. Most postganglionic sympathetic neurons secrete norepinephrine (ne) onto adrenergic receptors on the target cell. Most postganglionic parasympathetic neurons secrete acetylcholine onto muscarinic cholinergic receptors on the target cell. Sympathetic cholinergic neurons: symathetic postganglionic neurons that secrete ach rather than norepinephrine. Nonadrenergic, noncholinergic neurons: autonomic neurons secrete neither norepinephrine nor acetylcholine. Preganglionic sympathetic neurons project from the spinal cord to the adrenal medulla where they synapse. Chromaf n cells secrete the neurohormone epinephrine directly into the blood. Autonomic agonists and antagonists are important tools in research and medicine. Direct agonists and antagonists combine with the target receptor to mimic or block neurotransmitter action. Indirect agonists and antagonists act by altering secretion, reuptkae, or degradation of neurotransmitters.
