Regulation of Breathing – Key Vocabulary

A comprehensive set of vocabulary flashcards covering neural control centers, reflexes, chemoreceptors, CO₂–cerebral blood-flow interactions, and common breathing patterns discussed in the lecture.

Medulla Oblongata

Primary brainstem region that generates and controls the basic rhythm of breathing.

Dorsal Respiratory Group (DRG)

Medullary neurons that send inspiratory signals to the diaphragm and external intercostals.

Ventral Respiratory Group (VRG)

Medullary neurons that drive both inspiratory and expiratory accessory respiratory muscles.

Inspiratory Ramp

Gradually increasing neural output from the DRG that produces smooth, steady inspiration.

Pons

Brainstem area that modifies the medullary breathing pattern through pontine centers.

Apneustic Center

Pontine center that promotes prolonged, gasping inspirations when unchecked.

Pneumotaxic Center

Pontine center that limits inspiration and helps regulate breathing rate and depth.

Hering-Breuer Inflation Reflex

Stretch-receptor reflex that terminates inspiration when lungs become over-inflated.

Deflation Reflex

Reflex that triggers rapid breathing after sudden lung collapse or deflation.

Head’s Paradoxical Reflex

Airway stretch-receptor reflex that encourages deep breaths and assists newborns’ first inspiration.

Irritant Receptors

Airway sensors that initiate cough, bronchospasm, and tachypnea when exposed to noxious stimuli.

Vagovagal Reflex

Airway reflex activated by suctioning or intubation, leading to bronchospasm, cough, or bradycardia.

J-Receptors

Pulmonary capillary receptors that respond to edema or disease, causing rapid, shallow breathing.

Peripheral Proprioceptors

Sensors in muscles, joints, and tendons that increase ventilation during movement or pain.

Central Chemoreceptors

Medullary receptors that respond primarily to elevated CO₂ and decreased pH in cerebrospinal fluid.

Peripheral Chemoreceptors

Carotid and aortic bodies that detect changes in arterial O₂, CO₂, and pH—fast but less potent than central chemoreceptors.

CO₂–Cerebral Blood Flow Relationship

High arterial CO₂ dilates cerebral vessels and increases blood flow; low CO₂ constricts vessels and lowers flow.

Metabolic Autoregulation

Intrinsic regulation of cerebral blood flow based on local CO₂/H⁺ concentration changes.

Eupnea

Normal, quiet breathing pattern with tidal volume ≈ 500 mL, rate 12-20 bpm, and I:E ratio about 1:2.

Tachypnea

Rapid, shallow breathing rate > 20 breaths per minute.

Bradypnea

Abnormally slow breathing rate < 12 breaths per minute.

Apnea

Complete cessation of breathing (0 breaths per minute).

Apneustic

Deep, gasping inspiration with brief partial expiration, usually due to pontine damage.

Hyperpnea

Increased depth of breathing, often during exercise or metabolic acidosis.

Hypopnea

Decreased depth of breathing while maintaining respiratory rate; seen with sedation or obesity hypoventilation.

Hyperventilation

Elevated rate and/or depth of breathing causing decreased arterial CO₂ (respiratory alkalosis).

Hypoventilation

Reduced rate and/or depth of breathing leading to increased arterial CO₂ (respiratory acidosis).

Biot’s Respiration

Clusters of fast, deep breaths followed by abrupt apnea; associated with CNS damage or meningitis.

Cheyne-Stokes Respiration

Cyclic breathing pattern of crescendo-decrescendo tidal volumes with apnea; linked to brain injury or CHF.

Kussmaul’s Respiration

Deep, rapid breathing characteristic of severe metabolic acidosis (e.g., diabetic ketoacidosis).

Dyspnea

Subjective sensation of breathing discomfort or shortness of breath.

Orthopnea

Dyspnea occurring when lying flat and relieved by sitting or standing; common in heart failure.

Platypnea

Dyspnea that worsens in the upright position, often seen in hepatopulmonary syndrome.

Psychogenic Dyspnea

Hyperventilation linked to anxiety or panic disorders, often with chest pain and palpitations.

Breathing During Exercise

Increased CO₂ production and proprioceptor input cause faster and deeper ventilation to meet metabolic demand.

COPD Oxygen Sensitivity

Only a subset of COPD patients rely on hypoxic drive; oxygen therapy should not be withheld when needed.

Ventral Accessory Respiratory Muscles

Scalene, sternocleidomastoid, and other muscles engaged during forced breathing controlled via the VRG.

Hering-Breuer Deflation Reflex

Reflex acceleration of breathing triggered by acute lung collapse or deflation.

J-Receptor Tachypnea

Rapid, shallow breathing response to pulmonary capillary congestion or edema detected by J-receptors.

Proprioceptor-Driven Ventilation

Enhanced breathing triggered by movement or pain signals from muscles and joints.