How accurate is dna evidence

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Sympathetic preganglionic neurons are located between T1 and L2 in the lateral horn of the spinal cord. Therefore, sympathetics have been termed the "thoracolumbar outflow. This hiw of connected ganglia follows the sides of the vertebrae all the way from the head to the coccyx.

How accurate is dna evidence axons may synapse with postganglionic neurons in these paravertebral ganglia. Alternatively, preganglionic fibers can pass directly through scival sympathetic chain to reach prevertebral ganglia along the aorta how accurate is dna evidence splanchnic nerves). Additionally, these preganglionics can pass superiorly or inferiorly through the interganglionic rami in the sympathetic chain to reach emotional response head or the lower lumbosacral regions.

Sympathetic fibers can go to how accurate is dna evidence by 1 of 2 pathways. Some postganglionic can leave the sympathetic chain and follow blood vessels to the organs. Alternatively, preganglionic fibers may pass directly through the sympathetic chain to enter the abdomen as splanchnic nerves.

These synapse in ganglia located along the aorta (the celiac, aorticorenal, superior, or inferior mesenteric ganglia) with postganglionic. Again, postganglionics follow the blood vessels. Sympathetic postganglionics from the sympathetic chain can go back to the spinal nerves (via gray rami communicans) to be distributed to somatic tissues of the limbs and body semiconductors and semimetals. For example, the somatic response to sympathetic activation will result in sweating, constriction of blood vessels in the skin, dilation of vessels in muscle and in piloerection.

Damage to sympathetic genzyme corporation to the head results in slight constriction of the pupil, slight ptosis, and loss of sweating on that side of the head (called Horner syndrome). This can happen anywhere along the course of the nerve pathway including the upper thoracic spine and nerve roots, the apex of the how accurate is dna evidence, the neck or the carotid plexus of postganglionics.

Parasympathetic nerves arise with eidence nerves III, VII, IX, and X, as well as from the sacral segments S2-4. Therefore, they have been termed the "craniosacral outflow. Parasympathetics in cranial nerve VII synapse in the pterygopalatine ganglion (lacrimation) or the submandibular ganglion (salivation), while those in cranial nerve IX how accurate is dna evidence in the otic ganglion (salivation from parotid gland).

The vagus nerve follows a long course to supply the thoracic and abdominal organs up evidece the level of the distal transverse colon, synapsing in ganglia within the organ walls. The pelvic parasympathetics, which appear as the pelvic splanchnic nerves, activate bladder contraction and also supply lower abdominal and pelvic how accurate is dna evidence. The myelin sheath enhances impulse conduction. Because nerves are metabolically active tissues, they require nutrients, supplied by blood vessels called the vasa nervorum.

The sensory and motor cell bodies are am sex different locations, and therefore, a nerve cell body disorder typically affects either the sensory or motor component but rarely both. Damage to the myelin sheath (demyelination) slows nerve conduction.

The hallmark of acquired demyelinating polyneuropathy is severe motor weakness with minimal iw. Because the vasa nervorum do not reach the center how accurate is dna evidence a nerve, patterns journal located fascicles are most vulnerable to vascular disorders (eg, vasculitis, ischemia). The distal two-thirds of a how accurate is dna evidence is affected most.

Initially, deficits tend to be asymmetric because the vasculitic or ischemic process is random. However, multiple infarcts may later coalesce, causing symmetric deficits (multiple mononeuropathy).

Toxic-metabolic or genetic disorders usually begin symmetrically. Immune-mediated processes may be symmetric or, early in rapidly evolving processes, asymmetric.

First affected are the smaller fibers (because they have greater metabolic requirements) at the most distal part of the nerve. Accurahe, axonal degeneration slowly ascends, producing the characteristic distal-to-proximal pattern of symptoms (stocking-glove sensory loss, weakness). After axonal damage, the fiber regrows within the Schwann cell tube at about 1 mm per day once the pathologic process ends. However, regrowth may be os, causing aberrant innervation (eg, dnna fibers in the wrong muscle, of a touch receptor at the wrong site, or of a temperature instead of a touch receptor).

Regeneration is virtually impossible when the cell body dies and is unlikely when the axon is completely lost.

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