Boron Chapter 14 Autonomic Nervous System

Preganglionic neurons

Found in columns of cells in the brainstem and spinal cord, send axons out of the CNS and make synapses with postganglionic neurons

Postganglionic neurons

Synapses with preganglionic neurons in peripheral ganglia and are interposed between the CNS and their target cells

Sympathetic

Part of the autonomic nervous system that contains chiefly adrenergic fibers and tends to depress secretion, decrease the tone and contractility of smooth muscle, and increase heart rate

Parasympathetic

Part of the autonomic nervous system that contains chiefly cholinergic fibers, that tends to induce secretion, to increase the tone and contractility of smooth muscle, and to slow heart rate, and that consists of a cranial and a sacral part

Enteric

System of afferent neurons, interneurons, and motor neurons that form networks of neurons called plexuses that surround the gastrointestinal tract

Paravertebral Ganglia

Lie adjacent to the vertebral column, Chain of sympathetic ganglia extends from the neck to the coccyx, One ganglion is positioned at the level of each spinal root, but adjacent ganglia are fused in some cases

Superior cervical ganglion

Fusion of C1 to C4- supplies the head and neck

Middle cervical ganglion

Fusion of C5 and C6

Inferior cervical ganglion

C7 and C8

Stellate ganglion

Fusion of inferior cervical and thoracic ganglion

Prevertebral Ganglia

Named according to the arteries that they are adjacent to and include the celiac, superior mesenteric, aorticorenal, and inferior mesenteric ganglia

Edinger-Westphal nucleus

Parasympathetic subnucleus of the oculomotor complex in the midbrain, postganglionic fibers project to two smooth muscles of the eye: the constrictor muscle of the pupil and the ciliary muscle

Superior salivatory nucleus

Parasympathetic nucleus originates in rostral medulla, neurons travel in the facial nerve (CN VII), postganglionic fibers supply the lacrimal glands (tears) and two salivary glands (submandibular and sublingual).

Inferior salivatory nucleus

Parasympathetic nucleus originates in rostral medulla, neurons travel in the glossopharyngeal nerve (CN IX) , postganglionic fibers supply the parotid gland.

Nucleus ambiguus and dorsal motor nucleus

Parasympathetic nucleus originates in the medulla, neurons travel in the vagus nerve (CN X) , postganglionic fibers innervate the viscera of the thorax and abdomen, including the GI tract between the pharynx and distal end of the colon.

Nociception

The perception of a painful or injurious stimulus

Dermatome

Area of cutaneous innervation provided by a single dorsal root and its ganglion

Myenteric or Auerbach's plexus

Lies between the external longitudinal and the deeper circular smooth muscle layers involved primarily in the control of motility in the GI tract

Submucosal or Meissner's plexus

Lies between the circular muscle and the most internal layer of smooth muscle (muscularis mucosae) involved in the control of ion and fluid transport in the GI tract

β1 adrenergic receptors

Located in the heart and increase cardiac output

α1 adrenergic receptors

Predominate on blood vessels and cause vasoconstriction

α2 adrenergic receptors

On presynaptic terminals, suppresses the release of norepinephrine by negative feedback

β2 adrenergic receptors

In the bronchial muscle of the lungs, produces bronchodilation

β3 adrenergic receptors

In fat cells, involved in the regulation of lipolysis

Adrenal medulla

Special adaptation of the sympathetic system innervated by preganglionic neurons, located on the anterior medial border of the kidney, chromaffin cell release epinephrine into the bloodstream

Nitric oxide

Produced from l-arginine by a synthase, activates guanylyl cyclase and increases cGMP, lowers [Ca2+]i and relaxes vascular smooth muscle

Adenosine Triphosphate

Co-localized with NE in postganglionic sympathetic vasoconstrictor neurons, activates P2 purinoceptors, induces vascular constriction

Baroreceptor reflex

Mediated by preganglionic parasympathetic neurons in the dorsal motor nucleus of the vagus, receptors in the walls of large arteries (as the carotid sinus and arch of the aorta) are sensitive to changes in blood pressure