Respiratory System Part 2

Vocabulary flashcards covering key respiratory anatomy, physiology, mechanics, volumes, and disease concepts from Chapter 22, Part 2 lecture notes.

Alveolus

Microscopic air sac in the lung where gas exchange occurs.

Respiratory Bronchiole

Small airway leading to alveolar ducts; wrapped in smooth muscle and involved in gas conduction.

Alveolar Duct

Tiny passageway that connects respiratory bronchioles to alveolar sacs.

Alveolar Sac

Cluster of alveoli that share a common opening into an alveolar duct.

Respiratory Membrane

Three-layer barrier (alveolar epithelium, fused basement membranes, capillary endothelium) across which O₂ and CO₂ diffuse.

Squamous Epithelial Cell (Type I Pneumocyte)

Flat cell lining the alveolus; part of the respiratory membrane.

Capillary Endothelial Cell

Cell lining pulmonary capillaries; participates in the respiratory membrane.

Fused Basement Membrane

Shared basal lamina anchoring alveolar and capillary cells; minimizes diffusion distance.

Pneumonia

Inflammatory condition where alveoli fill with fluid, microorganisms, or mucus, impairing gas exchange.

Interstitium

Connective tissue network and space around lung air sacs containing elastin for recoil.

Pleura

Double-walled serous membrane surrounding lungs (visceral and parietal layers).

Visceral Pleura

Inner pleural layer covering and cushioning the lung surface.

Parietal Pleura

Outer pleural layer lining the thoracic cavity interior.

Intrapleural Pressure

Pressure in pleural space; normally ~4 mm Hg below intrapulmonary pressure to keep lungs expanded.

Transpulmonary Pressure

Difference between intrapulmonary and intrapleural pressures that keeps lungs inflated.

Pulmonary Ventilation

Mechanical movement of air into and out of the lungs.

External Respiration

Gas exchange between alveolar air and pulmonary blood.

Transport of Respiratory Gases

Circulatory delivery of O₂ and removal of CO₂ between lungs and tissues.

Internal Respiration

Gas exchange between systemic blood and body cells.

Boyle’s Law

Gas pressure is inversely proportional to volume; basis of ventilation mechanics.

Tidal Volume (VT)

Volume of air inhaled or exhaled during quiet breathing (~500 mL).

Respiratory Rate (RR)

Number of breaths per minute (normal 12–20).

Expired Minute Volume (VE)

Air exhaled in one minute; calculated VE = VT × RR.

Inspiratory Reserve Volume (IRV)

Air inhaled with maximal effort beyond tidal inspiration.

Expiratory Reserve Volume (ERV)

Air exhaled with maximal effort beyond tidal expiration.

Residual Volume (RV)

Air remaining in lungs after maximal expiration; prevents alveolar collapse.

Inspiratory Capacity (IC)

Maximum air that can be inspired after tidal expiration (IC = TV + IRV).

Functional Residual Capacity (FRC)

Air left in lungs after tidal expiration (FRC = ERV + RV).

Vital Capacity (VC)

Total exchangeable air (VC = VT + IRV + ERV).

Total Lung Capacity (TLC)

Sum of all lung volumes (TLC = TV + IRV + ERV + RV).

Forced Vital Capacity (FVC)

Vital capacity measured during a rapid, forceful exhalation.

Forced Expired Volume in 1 s (FEV1)

Volume exhaled during the first second of an FVC maneuver.

FEV1/FVC Ratio

Percentage of FVC exhaled in 1 s; normal > 80 %.

Peak Inspiratory Flow (PIF)

Highest flow rate achieved during forceful inspiration.

Peak Expiratory Flow (PEF)

Maximum flow rate reached during forceful expiration.

Compliance

Measure of lung expandability; high compliance = easy inflation, low compliance = stiff lungs.

Surfactant

Alveolar fluid that reduces surface tension, increasing compliance.

Pulmonary Fibrosis

Scarring of lung connective tissue that lowers compliance and causes restrictive disease.

Chronic Obstructive Pulmonary Disease (COPD)

Group of obstructive disorders (e.g., emphysema, chronic bronchitis) characterized by difficulty exhaling.

Obstructive Lung Disease

Condition with airflow limitation on exhalation; low FEV1 and low FEV1/FVC (< 70 %).

Restrictive Lung Disease

Condition with reduced lung expansion; low FEV1 and FVC but normal/high FEV1/FVC (> 70 %).

Diaphragm

Primary muscle of quiet inspiration, responsible for ~75 % of air movement.

Accessory Muscles of Inhalation

SCM, scalenes, pectoralis minor, serratus anterior; aid forced inspiration.

Accessory Muscles of Exhalation

Internal intercostals and abdominal muscles; assist in forced expiration.

Pneumothorax

Air in pleural space causing lung collapse.