The neurotransmitter secreted by postganglionic sympathetic fibers innervating sweat glands is: (Repeat)
Ans: C (Acetylcholine) Ref: Katznng, l0th edExplanation:* NE is the neurotransmilter of all postganglionic sympathetic fibers except the ones innervating the sweat glands, where acetylcholine is the neurotransmitter.Fig: Schematic diagram comparing some anatomic and neurotransmitter features of autonomic and somatic motor nerves. (ACh. acetylcholine; D, dopamine; Epi. epinephrine: NE. norepinephrine; N. nicotinic receptors: M. muscarinic receptors)Parasympathetic ganglia are present near the wall of the organ innervated.Some sympathetic postganglionic filters release acetylcholine or dopamine rather than norepinephrine.The adrenal medulla, a modified sympathetic ganglion, receives sympathetic preganglionic fibers and releases epinephrine and norepinephrine into the blood.The autonomic nervous system lends itself to division on anatomic grounds into two major portions: the sympathetic (thoracolumbar) division and the parasympathetic (craniosacral) division.The sympathetic preganglionic fibers leave the central nervous system through the thoracic and lumbar spinal nerves.The parasympathetic preganglionic fibers leave the central nervous system through the cranial nerves (especially the third, seventh, ninth and tenth) and the third and fourth sacral spinal roots.Most of the sympathetic preganglionic fibers terminate in ganglia located in the paravertebral chains that lie on either side of the spinal column.The remaining sympathetic preganglionic fibers terminate in prevertehral ganglia, which lie in front of the vertebrae, usually on the surface of the aorta.From the ganglia, postganglionic sympathetic fibers run to the tissues innervated. Some preganglionic parasympathetic fibers terminate in parasympathetic ganglia located outside the organs innervated: the ciliary, ptery gopalatine, submandibular, otic, and several pelvic ganglia.The majority of parasympathetic preganglionic fibers terminate on ganglion cells distributed diffusely or in networks in the walls of the innervated organs.
Norepinephrine
Epinephrine
Acetylcholine
Dopamine
Skin