Respiratory System Flashcards

Nose/mouth -> pharynx -> larynx -> trachea -> primary bronchi -> secondary bronchi -> tertiary bronchi -> bronchioles -> terminal bronchioles -> respiratory bronchioles -> alveolar ducts -> alveoli.

Tiny air sacs at the end of the respiratory tree where gas exchange occurs. Their thin walls (one cell thick) and enormous total surface area (about 70 square meters) maximize diffusion efficiency.

The mechanical process of breathing: moving air in (inspiration) and out (expiration) of the lungs through pressure changes created by the diaphragm and intercostal muscles.

The diaphragm contracts and flattens, external intercostals contract and lift the ribs. This increases thoracic volume, decreases pressure below atmospheric, and air flows in.

Passive process. The diaphragm and external intercostals relax, elastic recoil of the lungs decreases thoracic volume, increases pressure above atmospheric, and air flows out.

Pressure and volume are inversely related (at constant temperature). When lung volume increases during inspiration, pressure drops below atmospheric pressure, drawing air in.

A lipid-protein mixture produced by Type II alveolar cells that reduces surface tension in alveoli, preventing them from collapsing. Premature infants may lack surfactant, causing respiratory distress syndrome.

By simple diffusion across the respiratory membrane. Oxygen diffuses from alveoli (high O2) into blood (low O2). Carbon dioxide diffuses from blood (high CO2) into alveoli (low CO2).

About 98.5% bound to hemoglobin in red blood cells (as oxyhemoglobin). About 1.5% dissolved directly in plasma.

Three ways: about 70% as bicarbonate ions (HCO3-) in plasma, about 23% bound to hemoglobin (as carbaminohemoglobin), and about 7% dissolved in plasma.

An S-shaped (sigmoidal) curve showing the relationship between PO2 and hemoglobin saturation. At high PO2 (lungs), hemoglobin loads oxygen. At low PO2 (tissues), hemoglobin releases oxygen.

Increased temperature, increased CO2, increased H+ (lower pH), and increased 2,3-BPG. This is called the Bohr effect: active tissues get more oxygen delivery.

The volume of air inhaled or exhaled during a normal, resting breath. About 500 mL in adults.

The maximum amount of air that can be exhaled after a maximum inhalation. It equals tidal volume + inspiratory reserve volume + expiratory reserve volume.

The air remaining in the lungs after the most forceful expiration. About 1,200 mL. Prevents alveoli from completely collapsing.

In the medulla oblongata of the brainstem. It sets the basic rhythm of breathing and sends signals to the diaphragm and intercostal muscles.

CO2 levels in the blood (detected as changes in pH by central chemoreceptors in the medulla). Rising CO2 increases breathing rate. O2 levels are a secondary stimulus.

Conducting zone: nose to terminal bronchioles (warms, humidifies, filters air, no gas exchange). Respiratory zone: respiratory bronchioles to alveoli (where gas exchange occurs).

A double-layered serous membrane surrounding each lung. Parietal pleura lines the chest wall; visceral pleura covers the lung surface. Pleural fluid between them reduces friction during breathing.

Air enters the pleural space (through injury to chest wall or lung), breaking the negative pressure that keeps the lung inflated. The affected lung collapses.