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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.
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.
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.
Which division of the autonomic nervous system is characterized by short preganglionic and long postganglionic fibers?
The parasympathetic nervous system has long preganglionic and short postganglionic fibers
Is acetylcholine the substance released by axonal endings of the somatic efferent fibers and by the parasympathetic nerve fiber endings?
Yes, it does. In contrast, the sympathetic nerves release adrenaline
