Respiratory Physiology Quiz

Respiratory System Anatomy

• The upper respiratory tract includes the nose, nasal cavity, paranasal sinuses, pharynx, and larynx
• The nose and nasal cavity provide an airway for respiration, moisten and warm air, filter inhaled air, and contain olfactory receptors. They are also involved in speech.
• Paranasal sinuses are air-containing cavities in the skull lined with mucous membrane. Possible functions include decreasing skull weight, increasing voice resonance, buffering against facial trauma, insulating sensitive structures, humidifying and heating air, and supporting immunological defense.
• The pharynx is the upper part of the throat. It has three sections: nasopharynx (air passageway), oropharynx (food and air passageway), and laryngopharynx (connects throat to esophagus). It includes tonsils (nasopharyngeal and palatine/lingual).
• The larynx connects the laryngopharynx to the trachea and contains vocal folds. The thyroid gland sits on the outside of the larynx. The larynx's main function is protective, aiding in coughing and preventing food/fluid from entering the lungs.
• The lower respiratory tract includes the trachea, bronchi (and smaller bronchioles), lungs, and alveoli.

Respiratory System Physiology

• Respiration exchanges gases between the atmosphere, blood, and cells
• Components include pulmonary ventilation (breathing), external respiration (gas exchange between air and blood), and internal respiration (gas exchange between blood and cells)

Pulmonary Ventilation

• Inspiration (breathing in) occurs when alveolar pressure is less than atmospheric pressure. The diaphragm and external intercostal muscles contract, expanding the thoracic cavity. Forced inspiration utilizes accessory muscles.
• Expiration (breathing out) is a passive process. The diaphragm relaxes, and the thoracic cavity contracts causing air pressure to rise above atmospheric pressure, forcing air out. Forced expiration uses the abdominal muscles.

External Respiration

• External respiration is the exchange of gases between the air and blood in the alveoli and capillaries. Oxygen diffuses from the alveoli into the blood. Carbon dioxide diffuses from the blood into the alveoli.
• This process is driven by differences in partial pressures; normal partial pressure of oxygen (paO2) gradient: alveolar space= 100 mmHg, deoxygenated blood = 40 mmHg. Normal partial pressure of carbon dioxide (paCO2) gradient: alveolar space= 40 mmHg, deoxygenated blood = 45 mmHg.

Ventilation-Perfusion Matching

• Ventilation-perfusion matching is the balance of air flow into the alveoli and blood flow through the capillaries to facilitate external respiration.
• The ratio of ventilation (V) and perfusion (Q) must be balanced (approximately 0.8) for gas exchange. Disruptions (abnormal V/Q ratios) lead to hypoxemia (low blood oxygen).

Internal Respiration

• Internal respiration facilitates the exchange of oxygen and carbon dioxide between blood and the body’s cells. Oxygen diffuses from the blood into the cells. Carbon dioxide diffuses from the cells into the blood.

Type 1 and Type 2 Respiratory Failure

• Type 1 respiratory failure is characterized by the inability of the lungs to effectively exchange gases. It results in hypoxemia. Common causes include: lung disorders (asthma, COPD), pneumonia, pulmonary edema, fibrosis, and embolism.
• Type 2 respiratory failure involves the body's inability to effectively remove carbon dioxide. It results in hypercapnia. Potential causes include impaired CNS function, neuromuscular impairment, chronic bronchitis or COPD, and excessive inspiratory load. Both types can lead to complications if not treated promptly

Acid-Base Balance

• Arterial blood gases measure acid-base balance, aiding in determining the cause of respiratory issues. Blood pH is regulated by the lungs and kidneys.
• Compensation may occur by adjusting retention or excretion of CO2 (respiratory) and HCO3 (metabolic). The time course of compensation (acute vs. chronic) affects risk.

Lung Function Testing

• Spirometry measures lung function including lung volumes (Tidal Volume, Inspiratory Reserve Volume, Expiratory Reserve Volume, Residual Volume) and lung capacities (Total Lung Capacity, Functional Residual Capacity, Vital Capacity). Airflow measures, like FEV1/FVC ratio, differentiate between obstructive and restrictive lung disease.
• Peak flow meters aid in self-monitoring of lung function, particularly helpful for asthma patients. Spirometry to determine reversibility of airway obstruction is conducted by repeating the test 10-15 minutes after inhaling a bronchodilator. An increase in FEV1 indicates airway obstruction.

Effect of Fitness and Aging on the Respiratory System

• Proper respiratory function requires a strong cardiovascular system
• Exercise increases blood flow and oxygen consumption.
• Fitness improves lung capacity, gas diffusion, and strengthens respiratory muscles.
• Aging affects lung function through decreased lung compliance and weakened respiratory muscles. Smokers exhibit decreased exercise tolerance due to factors like nicotine-induced bronchoconstriction, lung fibrosis, excess mucus, cilia inhibition, and elastic fiber destruction

Asthma

• Asthma is a chronic inflammatory disorder marked by intermittent episodes of wheezing, coughing, and dyspnea, often worse at night or upon waking. Symptoms are associated with airway hyper-responsiveness.
• Possible diagnostic factors include: FEV1/FVC <0.7, significant reversibility post-bronchodilator challenge (>+12%), and sensitivity to broncho-provocation testing.
• Asthma exacerbations (status asthmaticus) can be life-threatening.
• Etiology and Risk factors includes: genetics, hygiene hypothesis, sex, maternal factors (pregnancy, smoking), perinatal factors, environmental factors (childhood, adulthood), and triggers.

COPD

• COPD (Chronic Obstructive Pulmonary Disease) is a chronic respiratory disease characterized by persistent symptoms, airflow limitation, chronic inflammation, and mucociliary dysfunction. Often a mix of emphysema and chronic bronchitis.
• COPD is associated with cigarette smoking, air pollutants, airway reactivity and genetic polymorphisms (Alpha-1 antitrypsin deficiency).
• Pathophysiology of emphysema includes imbalances in proteolytic and anti-proteolytic factors causing alveolar wall destruction and impaired lung recoil. In chronic bronchitis, chronic inflammation leads to mucus hypersecretion, ciliary dysfunction, and airway obstruction.

Treatment

• Asthma treatments often focus on relievers (SABA, SAMA, theophylline) and controllers (ICS, LABA). Biologics are reserved for severe cases.
• COPD treatments generally use the same short and long-acting beta-adrenergic agonists, long and short-acting antimuscarinics, and in some cases inhaled corticosteroids.