Respiratory System Physiology and Pathophysiology

Comprehensive vocabulary flashcards covering key terms, anatomical structures, physiological measurements, lung volumes, gas exchange principles, and respiratory disorders from the lecture notes.

Allergic Rhinitis

A condition characterized by the reaction of the nasal mucosa to a specific allergen, leading to symptoms like sneezing, watery eyes, thin discharge, and nasal congestion.

Epistaxis

Nosebleeding, managed by sitting upright, tilting the head forward, and applying direct pressure to the nasal soft tissue (ala).

Pharynx

A tube-like anatomical structure that connects the nasal and oral cavities to the lower respiratory and digestive passages.

Larynx

Also known as the voice organ, it connects the pharynx and the trachea and functions primarily in vocalization.

Alveoli

Microscopic air sacs representing the endpoint of the respiratory system and the primary site of gas exchange between air and the bloodstream.

Pores of Kohn

Interconnecting microscopic openings between adjacent alveoli that allow movement of air between them and can facilitate deep breathing or the spread of infection.

Type I Pneumocytes

Thin, flat squamous cells forming the wall of the alveoli that are directly involved in gas exchange.

Type II Pneumocytes

Specialized alveolar cells that synthesize and secrete surfactant to lower surface tension and prevent alveolar collapse.

Type III Alveolar Macrophages

Resident immune and defense cells located in the alveoli that phagocytose foreign particles such as dust and bacteria.

Surfactant

A lipoprotein complex that lowers surface tension inside the alveoli, decreasing the pressure needed to inflate them and preventing lung collapse.

Atelectasis

The collapse of alveolar air spaces leading to unventilated lung area, commonly caused by hypoventilation, airway obstruction, compression, or surfactant deficiency.

Infant Respiratory Distress Syndrome (RDS)

Also known as hyaline membrane disease, a disorder occurring in premature infants born before 24 weeks due to a lack of surfactant, causing alveolar collapse.

External Respiration

The process of gas exchange occurring between atmospheric air in the alveoli and blood in the pulmonary capillaries.

Internal Respiration

The process of gas exchange occurring between blood in systemic capillaries and surrounding body tissue cells.

$$\text{PaO}_2$$

The partial pressure of oxygen dissolved in arterial plasma, with a normal reference range of $75-100\,\text{mmHg}$.

$$\text{SaO}_2$$

The percentage of arterial hemoglobin saturated with oxygen, measured directly via an arterial blood gas test, with a normal range of $95-100\%$.

$$\text{SpO}_2$$

The percutaneous oxygen saturation level measured non-invasively using a pulse oximeter, with a normal range of $94-100\%$.

Oxyhemoglobin Dissociation Curve

A sigmoid ($S$-shaped) graph showing the relationship between oxygen partial pressure ($\text{PO}_2$) and the percentage of hemoglobin oxygen saturation.

Ventilation-Perfusion Ratio (V/Q Ratio)

The ratio of alveolar ventilation ($V$) to pulmonary capillary blood flow ($Q$), with a normal value of approximately $0.8$.

Low V/Q Ratio (Shunt)

A state where blood perfusion exceeds alveolar ventilation ($\text{V/Q} < 0.8$), allowing unoxygenated blood to pass into the systemic circulation.

High V/Q Ratio (Dead Space)

A state where alveolar ventilation exceeds blood perfusion ($\text{V/Q} > 0.8$), resulting from inadequate blood supply to ventilated alveoli.

Silent Unit

A severe V/Q state characterized by the absence or extreme reduction of both alveolar ventilation and pulmonary perfusion.

Tidal Volume (TV)

The volume of air inspired or expired during a single normal, quiet breathing cycle, normally about $500\,\text{mL}$.

Inspiratory Reserve Volume (IRV)

The maximum volume of air that can be forcibly inspired after a normal quiet inhalation, averaging $3,000\,\text{mL}$.

Expiratory Reserve Volume (ERV)

The maximum volume of air that can be forcibly expired after a normal quiet exhalation, averaging $1,200\,\text{mL}$.

Residual Volume (RV)

The volume of air remaining in the lungs after a maximal exhalation, averaging $1,200\,\text{mL}$, which cannot be directly measured by spirometry.

Vital Capacity (VC)

The maximum volume of air that can be exhaled after a maximal inhalation ($\text{VC} = \text{TV} + \text{IRV} + \text{ERV}$), averaging around $4,900\,\text{mL}$.

Total Lung Capacity (TLC)

The maximum volume of air contained in the lungs following a maximal inhalation ($\text{TLC} = \text{TV} + \text{IRV} + \text{ERV} + \text{RV}$), ranging from $4-6\,\text{L}$.

Asthma

A chronic, complex inflammatory airway disorder marked by airway hyperresponsiveness, smooth muscle constriction, and reversible airflow limitation.

Chronic Obstructive Pulmonary Disease (COPD)

A progressive pulmonary disease state characterized by chronic airflow limitation that is not fully reversible, encompassing emphysema and chronic bronchitis.

Emphysema

A type of COPD characterized by permanent enlargement and destruction of air spaces distal to terminal bronchioles and loss of alveolar elasticity ('Pink Puffer').

Chronic Bronchitis

A clinical diagnosis of COPD defined by the presence of a chronic productive cough and sputum production for at least 3 months per year for 2 consecutive years ('Blue Bloater').

Alpha-1 Antitrypsin Deficiency

A genetic risk factor for COPD where a lack of alpha-1 antitrypsin permits uninhibited neutrophil elastase activity, destroying lung tissue.

Cor Pulmonale

An emergency cardiovascular complication of chronic lung disease characterized by right ventricular heart failure due to elevated pulmonary artery pressure.

Intermittent Positive-Pressure Breathing (IPPB)

A short-term respiratory treatment using positive pressure delivered via ventilator to treat atelectasis and facilitate secretion clearance.

Vesicular Breath Sounds

Soft, low-pitched breath sounds heard over most peripheral lung fields where inspiration lasts longer than expiration.

Tracheal Breath Sounds

Very loud, high-pitched breath sounds normally heard only directly over the neck trachea, with equal inspiration and expiration durations.