Respiratory System - High-Yield Quick Reference

Word elements and terminology

• Overview: focus on word elements, anatomy, and terminology for breathing and oxygen conditions.

• Suffixes:

  • phagia = eating/swallowing (not to be confused with phonia, which means voice)

  • -nia = breathing

  • -centesis = surgical puncture (needle/catheter withdraw fluid)

  • -spasm = involuntary contraction (e.g., bronchial airways in asthma)

  • -ectomy = excision/removal (e.g., lobectomy)

  • -emia = blood condition (e.g., hypoxemia)

  • -osm ia = smell

  • -ox ia = oxygen

  • -eia = condition

  • -phonia = voice

  • -stenosis = narrowing/stricture

  • -therapy = treatment

• Common combining forms:

  • nasal / rhino = nose

  • phreno = diaphragm (context matters)

  • bronchio / broncho = bronchus (watch for bronchio as a trap)

  • bronchiolo = bronchioles

  • pneumo = air

  • pneumono = lung

  • lobo = lobe

• Important notes:

  • Bronchio can be mistaken as a combining vowel; bronchio is the combining form.

  • nasal is generally not used in surgical/medical term-building.

  • Pneumo = air; pneumono = lung; use correctly depending on context.

Lower respiratory tract structures

• Trachea: located in front of the esophagus; palpable in the neck; windpipe.

• Branching: trachea → right and left main bronchi → bronchi → bronchioles → alveoli.

• Alveoli: small air sacs; clustered like grapes; site of gas exchange.

• Alveolar-capillary membrane: diffusion interface for O2 into blood and CO2 into lungs.

• Diffusion outcome: oxygenation and ventilation depend on alveolar diffusion; disease here affects breathing.

Lungs and pleura

• Lungs: pneumono/pneuma terms refer to lungs; pneumono indicates lung-specific terms.

• Lobes: left lung = 2 lobes; right lung = 3 lobes; lobo = lobe.

• Pleura: double-layer around each lung

  • Parietal pleura: outer layer, lines chest wall

  • Visceral pleura: inner layer, adheres to the lung

  • Pleural cavity/space: between layers; contains fluid to reduce friction during expansion/contraction

• Summary: bronchi and alveoli are part of the lungs; diffusion and gas exchange occur at the alveolar level.

Breathing patterns and oxygen conditions

• Breathing terms:

  • Apnea: no breathing

  • Bradypnea: slow breathing

  • Tachypnea: rapid breathing

  • Dyspnea: difficult breathing / shortness of breath

  • Eupnea / Eupneia: normal breathing

  • Orthopnea: difficulty breathing when lying flat; requires upright position or pillows

• Oxygenation terms:

  • Hypoxemia: deficient arterial O2 in blood

  • Hypoxia: deficient O2 at tissues/organs

  • Anoxia: no O2

  • Hyperoxemia: excessive arterial O2

  • Hypercapnia: elevated arterial CO2 (ventilation not adequate)

Quick reference tips

• Remember diffusion site: alveolar-capillary membrane

• Differentiate pneumo- (air) vs pneumono (lung)

• Left lung has 2 lobes; right has 3 lobes

• Review textbook/lecture notes for full list of word elements and structures

Word elements and terminology

• Overview: Focus on word elements, anatomy, and terminology crucial for understanding breathing and oxygen conditions. Mastery of these prefixes, suffixes, and combining forms is fundamental for medical terminology.

• Suffixes:

  • -phagia = eating/swallowing. This suffix refers specifically to the act of consuming food or liquids, or the difficulty thereof (e.g., dysphagia - difficulty swallowing). Not to be confused with -phonia, which means voice.

  • -pnea = breathing. Describes various breathing patterns (e.g., apnea, dyspnea).

  • -centesis = surgical puncture. Often involves using a needle or catheter to withdraw fluid from a body cavity (e.g., thoracentesis).

  • -spasm = involuntary contraction. This often refers to sudden, involuntary muscle contraction, such as those that narrow the bronchial airways in asthma (bronchospasm).

  • -ectomy = excision/removal. Surgical removal of a part or all of an organ or structure (e.g., lobectomy - removal of a lung lobe).

  • -emia = blood condition. Indicates a substance or state present in the blood (e.g., hypoxemia - deficient oxygen in the blood).

  • -osmia = smell. Pertains to the sense of smell (e.g., anosmia - absence of the sense of smell).

  • -oxia = oxygen. Relates specifically to oxygen levels (e.g., hypoxia - deficient oxygen at the tissue level).

  • -eia = condition/state. A general suffix indicating a state or condition.

  • -phonia = voice. Refers to the voice or sound production (e.g., dysphonia - difficult or abnormal voice).

  • -stenosis = narrowing/stricture. Pathological narrowing of a passage or opening (e.g., tracheal stenosis).

  • -therapy = treatment. Refers to a course of remedial medical treatment (e.g., oxygen therapy).

• Common combining forms:

  • nas/o or rhin/o = nose. \"Naso\" is more general, while \"rhino\" is commonly used in conditions of the nose (e.g., rhinitis - inflammation of the nose).

  • phren/o = diaphragm. This combining form can also refer to the mind, so context is crucial when interpreting terms (e.g., phrenic nerve).

  • bronchi/o or bronch/o = bronchus. Bronchi/o is often seen, but bronch/o is also common (e.g., bronchitis, bronchoscope). Watch for bronchio as a combining form, not just a combining vowel.

  • bronchiol/o = bronchioles. Refers to the smaller airways branching off the bronchi (e.g., bronchiolitis).

  • pneum/o = air or lung. When referring to air, it's often in terms of gas or breath (e.g., pneumothorax - air in the chest cavity). When it refers to the lung, it often implies a condition affecting the organ as a whole.

  • pneumon/o = lung. Specifically refers to the lung tissue or organ (e.g., pneumonia - inflammation of the lung).

  • lob/o = lobe. Refers to a section or division of an organ, particularly the lungs or liver (e.g., lobectomy).

• Important notes:

  • "Bronchio" can be mistakenly identified only as a combining vowel; however, "bronchi/o" is a complete combining form meaning bronchus. Pay attention to the distinction between small changes in combining forms.

  • "Nasal" is generally not frequently used in formal surgical/medical term-building, with "rhino-" being more prevalent for conditions of the nose.

  • Differentiating between "pneumo-" (air, or sometimes lung) and "pneumono-" (specifically lung) is critical. "Pneumo-" can imply air presence, whereas "pneumono-" consistently refers to the lung itself. Use correctly depending on the specific context of the term.

Lower respiratory tract structures

• Trachea: Commonly known as the windpipe, it's a cartilaginous tube connecting the larynx to the bronchi. It's located anterior to the esophagus and is palpable in the neck. Its walls are supported by C-shaped hyaline cartilage rings, which prevent collapse during inhalation and allow the esophagus to expand during swallowing. It is lined with ciliated pseudostratified columnar epithelium that moves mucus and trapped particles upwards towards the pharynx.

• Branching:

  1. Trachea: The main airway extending from the larynx.

  2. Right and Left Main (Primary) Bronchi: The trachea bifurcates at the carina into these two large passages, each entering a lung.

  3. Lobar (Secondary) Bronchi: Within the lungs, the main bronchi divide further to supply each lobe (e.g., three in the right lung, two in the left).

  4. Segmental (Tertiary) Bronchi: These branch off the lobar bronchi, supplying bronchopulmonary segments.

  5. Bronchioles: These are smaller airways (<1 mm in diameter) that lack cartilage and consist mostly of smooth muscle, allowing for significant control over airflow.

  6. Terminal Bronchioles: The smallest bronchioles that lead to respiratory bronchioles.

  7. Respiratory Bronchioles: Contain some alveoli and participate in gas exchange.

  8. Alveolar Ducts: Branches of respiratory bronchioles, leading to alveolar sacs.

  9. Alveoli: The final, microscopic air sacs, clustered like grapes at the ends of the respiratory tree. They are the primary sites of gas exchange.

• Alveoli: These are tiny, balloon-like air sacs, numbering around $300$ million in the adult lungs, providing an enormous surface area (approximately $70$ square meters) for gas exchange. Their walls are extremely thin (single cell layer of Type I pneumocytes), facilitating rapid diffusion. Type II pneumocytes secrete surfactant, a complex lipoprotein that reduces surface tension and prevents alveolar collapse.

• Alveolar-capillary membrane: This ultra-thin, crucial interface is where gas exchange occurs. It consists of the alveolar epithelial cell, the basement membrane, and the capillary endothelial cell. Its total thickness is often less than $0.5$ micrometers, optimized for efficient diffusion of gases.

  • Diffusion Outcome: Efficient oxygenation (movement of O2 from alveoli to blood) and ventilation (movement of CO2 from blood to alveoli and out of the body) depend entirely on the integrity and efficiency of alveolar diffusion. Diseases that thicken or damage this membrane (e.g., pulmonary fibrosis, pneumonia, acute respiratory distress syndrome (ARDS)) significantly impair gas exchange, adversely affecting breathing and systemic oxygen delivery.

Lungs and pleura

• Lungs: These are the primary organs of respiration, located in the thoracic cavity. Terms like "pneumono/pneuma" often refer to the lungs, with "pneumono" specifically indicating lung-specific conditions or structures. Their main function is to facilitate gas exchange between the atmosphere and the bloodstream.

• Lobes: The lungs are divided into lobes by fissures.

  • Right lung = $3$ lobes: Superior, Middle, and Inferior lobes, separated by the horizontal and oblique fissures. It is larger and heavier than the left lung.

  • Left lung = $2$ lobes: Superior and Inferior lobes, separated by the oblique fissure. It also contains the cardiac notch, an indentation accommodating the heart.

  • The combining form "lobo-" exclusively refers to these distinct divisions (e.g., lobectomy).

• Pleura: A double-layered serous membrane that surrounds each lung and lines the thoracic cavity.

  • Parietal pleura: The outer layer that lines the inner surface of the thoracic wall, the diaphragm, and the mediastinum. It is sensitive to pain.

  • Visceral pleura: The inner layer that firmly adheres to the surface of the lung, including within the fissures. It is insensitive to pain.

  • Pleural cavity/space: A potential space between the parietal and visceral layers. It contains a thin film of serous pleural fluid (approximately $10-20$ mL), which acts as a lubricant, allowing the lungs to slide smoothly against the chest wall during breathing. This fluid also creates a pressure gradient that helps keep the lungs inflated. Conditions like pleurisy (inflammation) or pneumothorax (air in the pleural cavity) can severely impair lung function.

• Summary: The bronchi and alveoli are vital components within the lungs, forming the intricate pathway for air. The crucial process of diffusion and gas exchange, where oxygen enters the bloodstream and carbon dioxide is removed, occurs primarily at the alveolar-capillary membrane within the alveoli.

Breathing patterns and oxygen conditions

• Breathing terms:

  • Apnea: Complete cessation of breathing. Can occur in sleep apnea, certain neurological conditions, or drug overdose. Prolonged apnea is life-threatening.

  • Bradypnea: Abnormally slow respiratory rate (typically <$12$ breaths/minute in adults). Can be caused by electrolyte imbalance, metabolic alkalosis, narcotic overdose, or head injury.

  • Tachypnea: Abnormally rapid respiratory rate (typically >$20$ breaths/minute in adults). Often a compensatory mechanism for hypoxemia, acidosis, or seen in anxiety, pain, and fever.

  • Dyspnea: Subjective sensation of difficult or labored breathing, commonly described as "shortness of breath." A cardinal symptom of many cardiac and pulmonary diseases (e.g., heart failure, asthma, COPD).

  • Eupnea / Eupneia: Normal, quiet, rhythmic breathing. The healthy, effortless breathing pattern.

  • Orthopnea: Difficulty breathing that occurs when lying flat; the patient typically requires an upright position or multiple pillows to breathe comfortably. It's a classic sign of left-sided heart failure or severe pulmonary congestion.

• Oxygenation terms:

  • Hypoxemia: A condition characterized by a deficient amount of oxygen in the arterial blood (low arterial $PaO_2$). This is measured directly from an arterial blood gas (ABG) sample.

  • Hypoxia: A broader condition referring to deficient oxygen reaching the tissues and organs throughout the body, even if arterial oxygen levels might appear adequate (e.g., due to poor tissue perfusion). Can be generalized or localized.

  • Anoxia: A severe form of hypoxia, meaning the complete absence or near-complete absence of oxygen supply to tissues. Causes irreversible cellular damage if prolonged.

  • Hyperoxemia: An excessive amount of oxygen in the arterial blood (high arterial $PaO_2$). While sometimes iatrogenic (due to excessive oxygen therapy), it can also be harmful (e.g., oxygen toxicity).

  • Hypercapnia: An elevated level of carbon dioxide ($PaCO_2$ > $45$ mmHg) in the arterial blood. This typically indicates inadequate ventilation and can lead to respiratory acidosis. Common causes include hypoventilation due to respiratory muscle weakness, airway obstruction, or central nervous system depression.

Quick reference tips

• Remember the primary diffusion site: the extremely thin alveolar-capillary membrane is where efficient O2 and CO2 exchange occurs.

• Clearly differentiate "pneumo-" (air, or sometimes lung) vs. "pneumono-" (specifically lung) for precise medical terminology.

• Left lung has $2$ lobes (superior and inferior); right lung has $3$ lobes (superior, middle, and inferior). This anatomical difference is important for imaging and surgical planning.

• Review your textbook and lecture notes for a comprehensive list of word elements, anatomical structures, and pathological conditions to deepen your understanding beyond these core concepts.

• Pay close attention to suffixes like -phagia (eating/swallowing) and -phonia (voice) to avoid common conf