--- title: "Pulmonary Plexus | Anatomy and Physiology I" description: "Pulmonary plexus is the autonomic nerve network at the lungs' root that adjusts bronchial tone, blood vessel size, and mucus in Anatomy and Physiology I." canonical: "https://fiveable.me/anatomy-physiology/key-terms/pulmonary-plexus" type: "key-term" subject: "Anatomy and Physiology I" unit: "Unit 22" --- # Pulmonary Plexus | Anatomy and Physiology I ## Definition The pulmonary plexus is the network of autonomic nerves at the root of each lung. In Anatomy and Physiology I, it controls bronchoconstriction, vessel tone, and mucus secretion. ## What It Is The pulmonary plexus is the network of autonomic nerve fibers that sits at the root of each lung, right where the main bronchi, blood vessels, and lymphatics enter and leave. In Anatomy and Physiology I, you usually meet it while studying how the nervous system helps keep breathing efficient without you having to think about every breath. This plexus carries both sympathetic and parasympathetic input. The parasympathetic fibers mainly come from the vagus nerve and tend to promote bronchoconstriction and mucus secretion. Sympathetic fibers usually do the opposite by favoring bronchodilation and relaxing airway smooth muscle, which opens the passageways for more airflow. The plexus does not move air by itself. Instead, it fine-tunes the condition of the airways and nearby vessels so the lungs can match the body’s needs. If you are resting, the parasympathetic side keeps the airways slightly narrower and mucus production steady. If you are exercising or stressed, sympathetic activity helps air move more freely. That balance matters because the lungs are not just passive sacs. Their smooth muscle, glands, and blood vessels respond to autonomic signals all the time. The pulmonary plexus is the relay point where those signals are distributed to the lung tissue, especially around the bronchi and bronchioles. A common way to picture it is as a control hub at the lung entrance. The respiratory muscles create the big mechanical movement of breathing, but the pulmonary plexus adjusts the local plumbing and airway diameter so gas exchange can happen smoothly. If the airways tighten too much, airflow drops. If they widen appropriately, ventilation improves. You will also see this term connected to the idea of homeostasis. The body uses the pulmonary plexus to help keep airway resistance, mucus levels, and blood flow in a range that supports oxygen and carbon dioxide exchange. ## Why It Matters The pulmonary plexus shows how the nervous system and respiratory system work together instead of acting as separate topics. In Anatomy and Physiology I, that connection helps you explain why breathing is more than just moving the diaphragm. The airways need nervous control so they can respond to rest, exercise, stress, irritants, and disease. It also gives you a clean example of autonomic regulation. The sympathetic and parasympathetic branches do not always have equal effects in every organ, and the lungs are a good place to see that. The plexus helps you track which branch narrows or opens the bronchi, and how mucus secretion changes with that input. This term also matters when you study respiratory disorders. If airways constrict too much, airflow becomes harder, which can show up in symptoms like wheezing or shortness of breath. Even when you are not naming diseases yet, the plexus gives you a mechanism for why airway tone matters. On diagrams, the pulmonary plexus helps you connect the lung root to the bigger nervous system map. It sits near structures you already study in the thorax, so it is a useful label when tracing what reaches the lungs and what leaves them. ## Connections ### Autonomic Nervous System The pulmonary plexus is part of the autonomic nervous system, which controls body functions without conscious effort. In the lungs, autonomic signals adjust airway smooth muscle and gland activity. This is a good example of how the ANS keeps breathing responsive to changing conditions. ### Bronchoconstriction Bronchoconstriction is one of the main effects you connect to the pulmonary plexus, especially through parasympathetic stimulation. When bronchial smooth muscle tightens, airway diameter decreases and airflow becomes harder. That makes this term useful for understanding why nervous input changes how easily air moves through the lungs. ### Vasodilation The pulmonary plexus also influences blood vessel tone in the lung region, so vasodilation is part of the bigger picture. Changes in vessel diameter affect blood flow around the alveoli and can change how well gas exchange is supported. It ties the nervous system to the circulatory side of respiration. ### [Hering-Breuer Reflex](/anatomy-physiology/key-terms/hering-breuer-reflex) The Hering-Breuer Reflex is another lung-related control mechanism, but it works through stretch receptors and brainstem feedback rather than directly through the pulmonary plexus. Comparing the two helps you separate local autonomic control of airway tone from reflex control of breathing pattern. ## On the AP Exam A quiz item may ask you to identify the pulmonary plexus on a thoracic diagram or match it with its function in autonomic control of the lungs. You might also get a short answer asking which branch of the autonomic nervous system causes bronchoconstriction or why mucus secretion changes during parasympathetic activity. When you see a case question about wheezing, airway narrowing, or stress-related breathing changes, trace the answer back to airway smooth muscle control rather than only the diaphragm. In lab practicals, this term can show up as a structure at the lung root that you label as a nerve network tied to the bronchi. The best move is to connect the structure, its autonomic input, and its effect on airway diameter or secretion. ## pulmonary plexus vs bronchial artery The pulmonary plexus is a nerve network, while the bronchial artery is a blood vessel. They are both found near the lungs, but they do different jobs: the plexus sends autonomic signals, and the artery delivers oxygenated blood to lung tissues. If a question asks about control of airway tone or mucus, think plexus, not artery. ## Key Takeaways - The pulmonary plexus is an autonomic nerve network at the root of the lungs. - It helps control bronchoconstriction, bronchodilation, mucus secretion, and blood vessel tone. - Parasympathetic input, mainly through the vagus nerve, tends to tighten airways and increase secretion. - Sympathetic input generally relaxes airway smooth muscle and supports easier airflow. - You can think of it as a control hub that fine-tunes lung function, not as the structure that actually moves air. ## FAQs ### What is pulmonary plexus in Anatomy and Physiology I? The pulmonary plexus is the autonomic nerve network located at the root of each lung. It carries sympathetic and parasympathetic signals that adjust airway diameter, mucus secretion, and local blood vessel tone. In A&P, it is part of the nervous system control of respiration. ### Is the pulmonary plexus sympathetic or parasympathetic? It is both. The plexus contains sympathetic and parasympathetic fibers, and the two branches have different effects in the lungs. Parasympathetic input tends to cause bronchoconstriction and more mucus secretion, while sympathetic input tends to relax the airways. ### What does the pulmonary plexus control? It controls autonomic functions in the lungs, especially bronchial smooth muscle, mucus glands, and nearby vessels. That means it helps regulate airflow resistance and the conditions needed for gas exchange. It does not move air by itself, but it changes how open the airways are. ### How is the pulmonary plexus different from the bronchial artery? The pulmonary plexus is a nerve network, while the bronchial artery is a blood vessel. The plexus sends signals that change airway and vessel behavior, but the artery delivers blood to lung tissue. They are near each other at the lung root, which is why they can get confused on diagrams. ## Related Study Guides - [22.2 The Lungs ](/anatomy-physiology/unit-22/2-lungs/study-guide/IRaA60K8hYqmoOGP) ## About This Document Canonical Fiveable pages are available as Markdown at the same path plus `.md`. - [llms.txt](https://fiveable.me/llms.txt): index of Fiveable's sections and URL patterns - [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing - [MCP server](https://fiveable.me/mcp): call Fiveable as tools instead of fetching pages (`https://fiveable.me/api/mcp`) - [MCP server for AP teachers](https://fiveable.me/mcp/teachers): a teacher's classes, assignments and AP-rubric grading (`https://fiveable.me/api/mcp/teacher`) ## Structured Data ```json {"@context":"https://schema.org","@graph":[{"@type":"LearningResource","@id":"https://fiveable.me/anatomy-physiology/key-terms/pulmonary-plexus#resource","name":"Pulmonary Plexus | Anatomy and Physiology I","url":"https://fiveable.me/anatomy-physiology/key-terms/pulmonary-plexus","learningResourceType":"Concept explainer","educationalLevel":"AP® / High School","about":{"@id":"https://fiveable.me/anatomy-physiology/key-terms/pulmonary-plexus#term"},"audience":{"@type":"EducationalAudience","educationalRole":"student"},"dateModified":"2026-07-03T02:20:41.765Z","isPartOf":{"@type":"Collection","name":"Anatomy and Physiology I Key Terms","url":"https://fiveable.me/anatomy-physiology/key-terms"},"author":{"@type":"Organization","@id":"https://fiveable.me/editorial#content-team","name":"Fiveable Content Team","url":"https://fiveable.me/editorial","parentOrganization":{"@id":"https://fiveable.me/#organization"},"member":[{"@type":"Person","name":"Amanda DoAmaral","sameAs":["https://www.linkedin.com/in/adoamaral"]},{"@type":"Person","name":"Becky Bahr","sameAs":["https://www.linkedin.com/in/becky-bahr-b52743132"]}]},"publisher":{"@type":"Organization","name":"Fiveable","url":"https://fiveable.me"}},{"@type":"DefinedTerm","@id":"https://fiveable.me/anatomy-physiology/key-terms/pulmonary-plexus#term","name":"pulmonary plexus","description":"The pulmonary plexus is the network of autonomic nerves at the root of each lung. 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