Anatomy

1 4. The Autonomic Nervous System I. Introduction compare of the physical and involuntary flighty agreement of ruless The involuntary nervous system ( involuntary nervous system) is involved in maintaining basic homeostatic functions. The autonomic nervous system carries motor commands to the effectors of the cardiovascular, respiratory, digestive, urinary, and reproductive systems. In so doing, it helps maintain caudex pressure, water and salt balance, dissolved bollocks concentration, etc. The autonomic nervous system carries commands to smooth go throughs, glands, and the heart. These effectors are innervated by visceral motor nerve cells (recall that in straitened circumstances(p) muscles are innervated by material motor neurons). In the somatic nervous system, motor neuron bodies bulge out in the primaeval nervous system and their axons have a bun in the oven all the way to their effectors. In contrast, the autonomic nervous system makes mapping of p airs of motor neurons. The body of the first motor neuron lies in the CNS, and the body of the second motor neuron lies in an autonomic ganglion (e.g., the sympathetic trunk ganglia). Visceral motor neurons that originate in the CNS are called preganglionic neurons. Axons of preganglionic neurons, which are called preganglionic fibers, synapse with ganglionic neurons in the autonomic ganglia. Axons of the ganglionic neurons, which are called postganglionic fibers, drop dead to effectors.

Preganglionic fibers are keep down and lightly myelinated, and postganglionic fibers are mainly thinner and unmyelinated. How do the conduction velocities of these ! fibers compare with conduction velocities of somatic motor neuron fibers? All somatic motor neurons play out the neurotransmitter acetylcholine (ACh) at their neuromuscular junctions. ACh is always excitatory at the penurious muscle neuromuscular junction. All preganglionic fibers of the autonomic nervous system release ACh. The effect of ACh on the ganglionic neuron is always excitatory. Postganglionic fibers of the parasympathetic division of the ANS also release ACh, but it may be all stimulatory or inhibitory. This...If you want to get a full essay, point it on our website: OrderCustomPaper.com

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