Textbook Question
The neurotransmitter at all synapses and neuromuscular or neuroglandular junctions in the parasympathetic division of the ANS is
(a) Epinephrine
(b) Norepinephrine
(c) Cyclic-AMP
(d) Acetylcholine
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14. The Autonomic Nervous System
Introduction to the Autonomic Nervous System
Problem 18
Textbook Question
Which six plexuses in the thoracic and abdominopelvic cavities innervate visceral organs, and what are the effects of sympathetic versus parasympathetic stimulation?
Verified step by step guidance1
Identify the six major autonomic plexuses in the thoracic and abdominopelvic cavities: cardiac plexus, pulmonary plexus, esophageal plexus, celiac plexus, superior mesenteric plexus, and inferior mesenteric plexus. These plexuses are networks of nerves that innervate visceral organs.
Understand the role of the cardiac plexus: It innervates the heart and is involved in regulating heart rate and force of contraction. Sympathetic stimulation increases heart rate and force, while parasympathetic stimulation decreases them.
Examine the pulmonary plexus: It innervates the lungs and airways. Sympathetic stimulation dilates the bronchioles to increase airflow, while parasympathetic stimulation constricts the bronchioles to reduce airflow.
Explore the celiac plexus (solar plexus): It innervates the stomach, liver, pancreas, kidneys, and intestines. Sympathetic stimulation reduces digestive activity and redirects blood flow away from the digestive organs, while parasympathetic stimulation enhances digestion and increases blood flow to these organs.
Compare the effects of sympathetic and parasympathetic stimulation across all plexuses: Sympathetic stimulation generally prepares the body for 'fight or flight' responses by increasing heart rate, dilating airways, and inhibiting digestion, while parasympathetic stimulation supports 'rest and digest' functions by slowing heart rate, constricting airways, and promoting digestion.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Plexuses in the Thoracic and Abdominopelvic Cavities
Plexuses are networks of nerves that innervate specific regions of the body. In the thoracic and abdominopelvic cavities, six major plexuses include the cardiac, pulmonary, celiac, superior mesenteric, inferior mesenteric, and hypogastric plexuses. These plexuses play a crucial role in transmitting autonomic signals to visceral organs, influencing functions such as heart rate, digestion, and reproductive processes.
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Organization of the Thoracic Cavity
Sympathetic Nervous System
The sympathetic nervous system is part of the autonomic nervous system responsible for the 'fight or flight' response. It prepares the body for stressful situations by increasing heart rate, dilating airways, and inhibiting digestive processes. This system uses norepinephrine as a neurotransmitter to activate target organs, leading to heightened alertness and energy mobilization.
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Parasympathetic Nervous System
The parasympathetic nervous system is the counterpart to the sympathetic system, often referred to as the 'rest and digest' system. It promotes relaxation and conservation of energy by slowing the heart rate, enhancing digestion, and stimulating glandular activity. Acetylcholine is the primary neurotransmitter in this system, facilitating restorative processes in the body.
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