Autonomic Nervous System Targets
the autonomic nervous system
- Parasympathetic preganglionic neurons lie within cranial nerve nuclei 3, 7, 9, 10 and the sacral intermediolateral cell column of the spinal cord, from S2 to S4, collectively called "craniosacral."
- Sympathetic preganglionic neurons lie within the thoracolumbar intermediolateral cell column, from T1 to L2: they lie in the between the cranial and sacral parasympathetic regions.
neuropeptides
- Neurotransmitters are small molecules with transient effects; whereas, neuropeptides are generally packaged into larger vesicles and have more wide-reaching and long-lasting effects.
- Neuropeptides are organized into many different classes, which notably include pituitary and hypothalamic hormones, as well as many other categories.
- Target organs of the autonomic nervous system include endocrine and exocrine glands, nonglandular body organs, blood vessels, and skin, thus the autonomic nervous system reaches targets of highly varying functions.
- Cardiac rhythm abnormalities (arrhythmias)
- Respiratory failure
- Gut dysmotility
- Bladder dysmotility
- Skin manifestations, such as hair fiber loss and sweating
the enteric nervous system
The digestive tract also contains its own, separate autonomic nervous system.
- The enteric nervous system comprises numerous neurons distributed in myenteric and submucosal plexuses.
Physiology of digestion in brief:
- Food bolus trigger peristalsis, which propels food through the digestive tract.
- Enteric neural circuits increase intestinal blood volume: blood goes to our guts after we eat.
- Enteric neural circuits adjust secretomotor activity within the GI tract to regulate absorption of nutrients into the blood stream.
As a clinical correlate, psychopharmacologic drugs often affect enteric nervous system function.
- Acetylcholine increases peristalsis.
- Cholinesterase inhibitors, such as donepezil for dementia, increase circulating levels of acetylcholine, and can result in diarrhea, and anticholinergic drugs (such as tricyclic antidepressants) can cause constipation.