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Preganglionic sympathetic fibers trigger the release of?
Preganglionic sympathetic fibers trigger the release of acetylcholine at the synapse with postganglionic neurons in the sympathetic ganglia. This neurotransmitter binds to nicotinic acetylcholine receptors on the postganglionic neuron, which then propagate the signal to release norepinephrine at the target tissue.
Which autonomic nervous system fibers release norepinephrine?
The autonomic nervous system fibers that release norepinephrine are primarily the postganglionic sympathetic fibers. These fibers originate in the sympathetic ganglia and project to various target organs, where they release norepinephrine to mediate the "fight or flight" response. In contrast, the preganglionic sympathetic fibers release acetylcholine.
Are parasympathetic postganglionic fibers generally come from adrenergic fibers?
No, parasympathetic postganglionic fibers do not come from adrenergic fibers. Parasympathetic postganglionic fibers release acetylcholine as their neurotransmitter, whereas adrenergic fibers release norepinephrine.
Where do all postganglionic efferent fibers terminate?
Postganglionic efferent fibers terminate at effector organs, which include smooth muscles, cardiac muscles, and glands. These fibers are part of the autonomic nervous system, which is divided into the sympathetic and parasympathetic systems. In the sympathetic system, they typically release norepinephrine, while in the parasympathetic system, they primarily release acetylcholine to exert their effects on target tissues.
How would a drug that stimulates acetylcholine receptors affect the sympathetic nervous system?
Preganglionic fibers for the SNS release ACh; so a drug that stimulates ACh receptors would stimulate the postganglionic fibers of sypathetic nerves, resulting in increased sympathetic activity
What secretes norepinephrine adrenergic fibers?
Norepinephrine is mainly secreted by the adrenal medulla and the postganglionic fibers of the sympathetic nervous system, which are also known as adrenergic fibers. These fibers release norepinephrine in response to stress or arousal, helping to initiate the body's fight or flight response.
Postganglionic axons secrete acetylcholine cholinergic fibers?
Parasympathetic
What releases catecholamines as a neurotransmitter?
it would be postganglionic sympathetic fibers
What are norepinephrine releasing fibers called?
Andrenergic fibers release Norepinephrine and Cholinergic fibers release Acetylcholine.
Where do sympathetic postganglionic fibers end?
Sympathetic postganglionic fibers end in effector organs such as smooth muscles, cardiac muscles, and glands. They innervate these structures to modulate their activity in response to stress or stimulation of the sympathetic nervous system.
Does the sympathetic division secrete norepinephrine?
Yes, when stimulated the sympathetic postganglionic fibers release norepinepherine (20%) and epinepherine (80%).
Why does acetylcholine causes vaso-dilation?
In some muscle tissue acetylcholine causes vaso-dilation, but not all. Norepinephrine is the opposite competor/effector of acetylcholine. Acetylcholine is present in all preganglionic fibers, both parasympathetic and sympathetic. Acetylcholine is present in postganglionic parasympatic fibers, where norepinephrine is present in the postganglionic sympathetic fibers. In some tissues acetylcholine causes constriction. Can also reduce heart rate vi the vagus nerve. Acetylcholine is the only neurotransmitter used in the somatic nervous system! Acetylcholine can effect vasodilation by several mechanisms, including activation of endothelial nitric oxide (NO) synthase and prostaglandin (PG) production. In human skin, exogenous Acetylcholine increases both skin blood flow and bioavailable NO levels, but the relative increase is much greater in skin blood flow than NO. So this may lead us to speculate that acetylcholine may dilate cutaneous blood vessels through PGs, as well as NO. In some muscle tissue acetylcholine causes vaso-dilation, but not all. Norepinephrine is the opposite competor/effector of acetylcholine. Acetylcholine is present in all preganglionic fibers, both parasympathetic and sympathetic. Acetylcholine is present in postganglionic parasympatic fibers, where norepinephrine is present in the postganglionic sympathetic fibers. In some tissues acetylcholine causes constriction. Can also reduce heart rate vi the vagus nerve. Acetylcholine is the only neurotransmitter used in the somatic nervous system! Acetylcholine can effect vasodilation by several mechanisms, including activation of endothelial nitric oxide (NO) synthase and prostaglandin (PG) production. In human skin, exogenous Acetylcholine increases both skin blood flow and bioavailable NO levels, but the relative increase is much greater in skin blood flow than NO. So this may lead us to speculate that acetylcholine may dilate cutaneous blood vessels through PGs, as well as NO.
