Biomedical Engineering Reference
In-Depth Information
post-ganglionic parasympathetic neurons, all preganglionic sympathetic neurons,
and some postganglionic sympathetic fibers.
The sympathetic innervation consists of cell bodies in the lateral horn of the
spinal cord (intermediolateral cell columns from T1 to L3). These cell bodies
belong to general visceral efferent (GVE) neurons and preganglionic neurons.
The sympathetic trunks (a paired bundle of nerve fibers laterally along the spine
column from the base of the skull to the coccyx) generate the paravertebral
ganglia, or ganglia of the sympathetic trunk. Prevertebral ganglia (collateral or
preaortic ganglia) localize between the sympathetic chain and supplied abdominal
and pelvic organs. These ganglia give rise to postganglionic neurons. In fact,
cardiopulmonary, thoracic splanchnic, sympathetic nerves that originate from the
paravertebral ganglia contain noradrenergic postganglionic efferent and visceral
afferent (sensory) fibers (general visceral afferent [GVA] neurons). Noradrenaline
released from postganglionic sympathetic neurons participates to the control of
airway behavior.
Neuropeptides
Neuropeptides contribute to regulate the body's functions, in particular the body's
respiration, as: (1) para- and autocrine messengers; (2) neurohormones, which are
produced by central neurons and reach their target cells of the nervous system
via the blood circulation; (3) circulating hormones, which target remote cells; and
(4) neurotransmitters and neuromodulators, which are released from nerve endings
to act locally on nearby cell. A given neuron can manufactures one or more peptide
hormones together with one or more neurotransmitters.
Numerous neuropeptides can be identified in the lung or influence its function.
These neuropeptides are synthesized in neurons and released from nerve termi-
nals. They encompass vasoactive intestinal peptide, bombesin, gastrin-releasing
peptide (GRP), calcitonin gene-related peptide (CGRP), which are produced by
neuroendocrine cells, in addition to serotonin [
1544
]. Calcitonin, endothelins, and
angiotensin-converting enzyme, which forms angiotensin and degrades bradykinin,
localize mainly to the endothelium.
In humans, the VIP/secretin family of brain-gut endocrine peptides include
10 members. In addition to vasoactive intestinal peptide and secretin, a hor-
mone that controls water homeostasis throughout the body, this family encom-
passes adenylate cyclase-activating polypeptide AdCyAP1, or pituitary adenylate
cyclase-activating peptide (PACAP), which may act as a sensory neuropeptide,
8
PACAP-related peptide (PRP), peptide histidine methionine (PHM), glucagon,
8
Two AdCyAP1 isoforms exist: AdCyAP1
38
and truncated AdCyAP1
27
(C-terminally truncated
AdCyAP1
Δ
CT
).
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