--- title: "Dorsal Respiratory Group (DRG) | Anatomy I" description: "Dorsal respiratory group (DRG) is a medullary neuron cluster that starts inspiration and drives the diaphragm in Anatomy and Physiology I." canonical: "https://fiveable.me/anatomy-physiology/key-terms/dorsal-respiratory-group-drg" type: "key-term" subject: "Anatomy and Physiology I" unit: "Unit 22" --- # Dorsal Respiratory Group (DRG) | Anatomy I ## Definition The dorsal respiratory group (DRG) is a cluster of neurons in the medulla oblongata that starts the basic rhythm of inhalation. In Anatomy and Physiology I, you study it as part of the brainstem control of breathing. ## What It Is The dorsal respiratory group (DRG) is the main inspiratory control center in the medulla oblongata, the lower part of the brainstem. In Anatomy and Physiology I, it shows up when you trace how the nervous system automatically turns breathing on and off without you having to think about it. The DRG contains neurons that fire in a rhythmic pattern and send signals to the inspiratory muscles, especially the diaphragm and the external intercostals. When the DRG activates these muscles, the thoracic cavity expands, pressure inside the lungs drops, and air flows in. That makes the DRG part of the chain that links the nervous system to the mechanics of inhalation. A simple way to picture it is this: the lungs do not pull air in by themselves. The DRG sends the message that tells the diaphragm to contract and flatten. That muscle action creates the volume change that makes inhalation happen. So the DRG is not moving air directly, it is controlling the muscles that create the pressure change needed for breathing. The DRG is especially tied to quiet, automatic breathing. It helps set the basic breathing rhythm at rest, then adjusts that rhythm based on input from sensory receptors and other brainstem centers. If carbon dioxide rises, for example, the respiratory control system can increase the drive to breathe faster or deeper. The DRG is one part of that larger feedback system. This is why the term usually appears alongside the medulla oblongata, central chemoreceptors, and inspiratory muscles. Those terms fit together in the same pathway: chemical signals and nerve input influence the medulla, the DRG coordinates inspiration, and the diaphragm carries out the action. ## Why It Matters The dorsal respiratory group matters because it connects nervous system control to the physical act of breathing. In Anatomy and Physiology I, breathing is not just a lung topic, it is a homeostasis topic. Your body has to keep oxygen moving in and carbon dioxide moving out, and the DRG is part of the brainstem circuitry that keeps that cycle going. It also helps you understand why inhalation is active. The DRG sends output to the inspiratory muscles, which means the diaphragm must contract before air enters the lungs. That detail shows up in diagrams, labeling questions, and process questions about how thoracic volume and pressure change during inspiration. The DRG is useful for connecting several course units at once. You can link it to nervous tissue, the medulla oblongata, respiratory muscles, and gas exchange. If you can explain how the DRG starts inspiration, you can usually explain the rest of the breathing sequence more clearly. It also gives you a clean way to separate automatic breathing control from voluntary control. You can choose to hold your breath or breathe faster for a short time, but the DRG is part of the automatic baseline that keeps respiration going when you are not consciously controlling it. ## Connections ### [Medulla Oblongata](/anatomy-physiology/key-terms/medulla-oblongata) The DRG is located in the medulla oblongata, so the medulla is the brainstem region that houses this breathing center. When you identify the medulla on a diagram, you are also finding the area that contains the basic automatic control for respiration. That connection helps explain why brainstem injury can disrupt breathing. ### Diaphragm The diaphragm is the main muscle the DRG activates during inhalation. The DRG sends motor signals that make the diaphragm contract and flatten, which increases thoracic volume. If you are tracing the breathing process step by step, the DRG is the controller and the diaphragm is one of the main effectors. ### Inspiratory Muscles The DRG primarily drives inspiratory muscles, not the muscles used for quiet exhalation. That is why it is tied so closely to inspiration in textbook diagrams and lecture notes. It helps you separate the command center from the muscle group that actually expands the chest cavity. ### [Central Chemoreceptor](/anatomy-physiology/key-terms/central-chemoreceptor) Central chemoreceptors monitor carbon dioxide-related changes in the blood and cerebrospinal fluid environment, then influence respiratory centers in the medulla. Their input can increase the drive from the DRG when CO2 rises. That feedback link is how breathing adjusts to body chemistry instead of staying fixed. ## On the AP Exam A quiz item might ask you to identify the part of the brainstem that initiates inhalation, or a diagram question may show the medulla and ask which center controls the diaphragm. You may also need to trace the sequence: DRG activates, inspiratory muscles contract, thoracic volume increases, intrapulmonary pressure drops, and air enters the lungs. In a short answer or lab-style question, use the DRG to explain why breathing is automatic at rest and why inhalation is an active process. If the prompt mentions rising carbon dioxide, connect that chemical change to increased respiratory drive through the medulla. The best answers name the DRG and then follow the pathway to the muscle action it produces. ## dorsal respiratory group (DRG) vs Apneustic Center The DRG and the apneustic center are both part of breathing control in the brainstem, but they are not the same. The DRG mainly generates the basic inspiratory rhythm in the medulla, while the apneustic center in the pons helps prolong inspiration. If a question asks which structure starts the breathing pattern, DRG is the better match. ## Key Takeaways - The dorsal respiratory group is a cluster of neurons in the medulla oblongata that helps start the rhythm of breathing. - Its main job is to drive inspiration by signaling the diaphragm and other inspiratory muscles to contract. - When the DRG activates these muscles, the thoracic cavity expands, pressure drops, and air moves into the lungs. - It works as part of an automatic feedback system, so breathing adjusts to the body's need for oxygen and removal of carbon dioxide. - If you remember one thing, remember this: the DRG is the brainstem control center that kicks off quiet inhalation. ## FAQs ### What is dorsal respiratory group (DRG) in Anatomy and Physiology I? The dorsal respiratory group is a group of neurons in the medulla oblongata that helps generate the basic rhythm for inhalation. It sends signals to the inspiratory muscles, especially the diaphragm, so air can enter the lungs. In A&P I, it is part of the nervous control of breathing. ### Where is the dorsal respiratory group located? It is located in the medulla oblongata, which is part of the brainstem. That location matters because the medulla contains several automatic control centers for survival functions, including breathing. If you see a brainstem diagram, the DRG belongs in the medulla region. ### Does the dorsal respiratory group control inhalation or exhalation? The DRG mainly controls inhalation. It activates the inspiratory muscles, which expands the thoracic cavity and draws air into the lungs. Quiet exhalation is usually passive, so it does not depend on the DRG in the same direct way. ### How is the DRG different from the apneustic center? The DRG helps generate the basic inspiratory rhythm, while the apneustic center in the pons helps prolong inspiration. They are both involved in breathing control, but they do different jobs. If a question asks about the main inspiratory drive, the DRG is the better answer. ## Related Study Guides - [22.3 The Process of Breathing ](/anatomy-physiology/unit-22/3-process-breathing/study-guide/oe2Sz6Yq9gIM9Ca3) ## 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/dorsal-respiratory-group-drg#resource","name":"Dorsal Respiratory Group (DRG) | Anatomy I","url":"https://fiveable.me/anatomy-physiology/key-terms/dorsal-respiratory-group-drg","learningResourceType":"Concept explainer","educationalLevel":"AP® / High School","about":{"@id":"https://fiveable.me/anatomy-physiology/key-terms/dorsal-respiratory-group-drg#term"},"audience":{"@type":"EducationalAudience","educationalRole":"student"},"dateModified":"2026-07-03T02:20:38.182Z","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/dorsal-respiratory-group-drg#term","name":"dorsal respiratory group (DRG)","description":"The dorsal respiratory group (DRG) is a cluster of neurons in the medulla oblongata that starts the basic rhythm of inhalation. 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