parasympathetic nerve


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par·a·sym·pa·thet·ic nerve

one of the nerves of the parasympathetic nervous system.

par·a·sym·pa·thet·ic nerve

(par'ă-sim'pă-thet'ik nĕrv)
One of the nerves of the parasympathetic nervous system.

parasympathetic nerve

A nerve composed of axons of the parasympathetic division of the autonomic nervous system. Parasympathetic innervation is always a chain of two consecutive axons. The first axon, the preganglionic parasympathetic axon, has its cell body in the brainstem or in the intermediate gray column of spinal cord segments S2–S4; the first axon leaves the brainstem through the oculomotor (CN III), facial (CN VII), glossopharyngeal (CN IX), or vagus (CN X) nerve, or it leaves the sacral spinal cord through a pelvic splanchnic nerve. The second axon in the chain, the postganglionic parasympathetic axon, has its cell body in a peripheral ganglion near its target tissue. The main transmitter used by both pre- and postganglionic parasympathetic axons is acetylcholine. In general, stimulation of parasympathetic nerves relaxes the body tone.
See also: nerve
References in periodicals archive ?
(b) Parasympathetic nerve and parasympathetic nerve under general anaesthesia.
These frequencies are classified into (1) ultra low frequencies (ULF; > 5 hrs cycle length) that include the circadian rhythm (Braga et al., 2002; Overton 2001; Williams et al., 2002) (2) very low frequencies (VLF; > 25 sec cycle length) that are supposed to be affected by temperature regulation (Aoki 2001; Vornanen 2002) and humoral systems (Porter and Rivkees, 2001) (3) low frequencies (LF; > 6 sec cycle length in humans) that are sensitive to changes in cardiac sympathetic and presumably parasympathetic nerve activity (Lanfranchi and Somers, 2002; Malpas, 2002) (4) high frequencies (HF; 2.5 to 6 secs cycle length in humans) that are synchronized to the respiratory rhythm (Barbieri 2002) and are primarily modulated by cardiac parasympathetic inervation (Rentero et al., 2002).
The researchers measured heart rate variability while the volunteers engaged in controlled breathing (12 breaths/min for 1 minute), rested in a tilted, 70-degree head-up position (4 minutes), and engaged in a cold pressor test (CPT) during which a lower arm was immersed in ice-cold water (2 minutes): "Controlled breathing stimulates parasympathetic nerve activity, whereas tilting and CPT stimulate sympathetic nerve activity." Additional tests included oral glucose tolerance test, low-dose tetracosactin stimulation test, corticotropin releasing hormone stimulation test, oral dexamethasone suppression test, and diurnal salivary and urinary Cortisol testing as well as anthropometric measures.
Because the parasympathetic nerve is activated when the subject is sleep on 1 stage of sleep, the heart rate is decreased then the SDNN, RMSSD, and pNN50 tend to increase, while they tend to decrease when the subject is awaken.
[6] Nerve supply to the sweat glands in the body is sympathetic cholinergic except to the sweat glands on palms of the hands, which is supplied by the parasympathetic nerve. [7] As idiopathic hyperhidrosis involves palms, sole, and other areas of the skin, both sympathetic and parasympathetic dysfunction is expected in this condition.
(3) Effect of Kidsolone on electrically induced contractions - electrical stimulation of this tissue causes parasympathetic nerve remnants in the trachea to release the transmitter acetylcholine.
Involvement of the parasympathetic nerve pathway inhibits normal constriction of the pupil and results in dilation.
Frequency fluctuations in HRV in the range of 0.04-0.15 Hz (low frequency, LF) are considered to be markers of sympathetic and parasympathetic nerve activity, and high frequency (HF) fluctuations in the range of 0.15-0.4 Hz are considered to be markers of parasympathetic nerve activity.
The SA node, the primary pacemaker of the heart, is densely innervated by parasympathetic nerve fibers.
Its mechanism has been described as resulting from stimulation of afferent parasympathetic nerve endings due to traction on the dura, causing a reflex-coeliac (vasovagal) reaction4.
Frey's syndrome occurs when misdirected regenerating postganglionic parasympathetic nerve fibers invade the severed postganglionic sympathetic fibers that supply the sweat glands.

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