Respiratory System Overview

Respiratory System Overview

• The respiratory system facilitates breathing, also known as ventilation.
• The upper respiratory tract comprises the larynx, nasal cavity, mouth, and trachea.
• The lower respiratory tract includes bronchial branches and the lungs.
• Pulmonary ventilation describes airflow into and out of the lungs.
• Alveolar ventilation refers to airflow into and out of alveoli, the sites of gas exchange in the lungs.
• The respiratory tree's pathway is: primary bronchi, secondary bronchi, bronchioles, terminal bronchioles, and alveoli.
• The trachea connects the larynx to the primary bronchi.
• Lungs are enclosed by pleural membranes and located within the thoracic cavity.
• The ideal gas law describes the relationship between pressure, volume, temperature, and number of gas molecules.
• Type II alveolar cells produce surfactant, a chemical that prevents alveolar collapse.
• Type I alveolar cells allow for rapid gas diffusion due to their thin membranes.
• Alveolar sacs consist of a single layer of simple squamous epithelium, promoting efficient gas diffusion.
• The pharynx is a shared passage for both respiration and digestion.
• Inhalation occurs when the diaphragm and external intercostal muscles contract, increasing thoracic volume.

Gas Exchange and Pressure

• Dalton's Law states that total pressure in a gas mixture equals the sum of individual gas partial pressures.
• Air flows into the lungs when lung pressure is lower than atmospheric pressure.
• Air moves out of the lungs during exhalation as lung volume decreases.
• Intrapleural pressure typically is -3 mm Hg.
• Active exhalation involves contraction of the abdominal muscles.
• Lung blood vessels cover approximately 80-90% of the alveolar surface.
• Lung blood flow is higher, while blood pressure is lower, compared to other tissues.
• Airflow is directly proportional to the pressure gradient and inversely proportional to resistance.