The Autonomic Nervous System
What is a preganglionic axon?
A motor neuron cell body located in the spinal cord or brain. The axon synapses with a second motor neuron located in an autonomic ganglion outside the spinal cord.
What is the major neurotransmitter in the parasympathetic system?
Acetylcholine
Name five types of ganglia found in the parasympathetic division and what they control.
Ciliary ganglion: associated with cranial nerve III, this targets the intrinsic eye muscles which change the pupil and lens. Pterygopalatine ganglion & Submandibular ganglion: associated with CN VII, the target organs are for tear production, nasal glands and salivary glandsOtic ganglion: associated with CN IX, the target glands are the parotid glandsIntramural ganglia: associated with CN X, the target glands are the visceral organs within the thoracic cavity.
Explain in detail how the sympathetic nervous system functions during an emergency.
During an emergency, the sympathetic system accelerates the heartbeat, dilates the bronchi, and increases the breathing rate supplying needed oxygen and causes the liver to deliver more glucose and inhibits the digestive tract.
Name four types of ganglia found in the sympathetic division and what they control.
Sympathetic trunk ganglia or lateral ganglia: located on both sides of the spinal cord, these contain the ganglia for the sympathetic nervous system that controls the effector organs in the trunk, head and limbs. Celiac ganglion: largest of the ganglia, these ganglia innervate the digestive tract. Superiomesenteric ganglion: innervates the small intestine and parts of the large intestineInferior mesenteric ganglion: innervates the large intestine, kidneys, bladder and sex organs.
Describe the effects caused by the parasympathetic and sympathetic nervous systems on heart blood vessels, the lungs and the digestive tract.
The parasympathetic nervous system has no effect on heart blood vessels, constricts bronchioles of the lungs and increases peristalsis and relaxes the sphincters of the digestive tract. The sympathetic nervous system dilates heart blood vessels, dilates bronchioles of the lungs and decreases the activity of and constricts the sphincters of the digestive tract.
What type of internal responses are promoted by the parasympathetic nervous system?
The parasympathetic system promotes all the internal responses we associate with a relaxed state.
Why is the sympathetic system also called the thoracolumbar division?
The sympathetic system is also called the thoracolumbar division because this division contains preganglionic fibers from the thoracic and upper lumbar segments of the spinal cord, in the lateral gray horns.
What are the two divisions of the autonomic nervous system and how do they function relative to each other?
The two divisions of the autonomic system are the sympathetic and parasympathetic systems. These two divisions cause essentially opposite effects on the same visceral organ; if one stimulates, the other inhibits.
