Chapter 13 – The Respiratory System (Physiology B, Week 5)

Vocabulary flashcards covering key terms and concepts from Chapter 13 notes on the human respiratory system.

Nose Breathing

Preferred over mouth breathing because incoming air is warmed, moistened, and filtered in the nasal passages before reaching the lungs.

Tracheal Cilia

Hair-like projections that beat superiorly, moving mucus laden with dust and debris toward the throat for removal.

Goblet Cells

Mucus-secreting cells located in respiratory epithelium; their mucus traps dust and pathogens.

Conducting Zone

All respiratory passageways that carry air to and from the respiratory zone; no gas exchange occurs here.

Respiratory Zone

Site of gas exchange; includes respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.

Right Main Bronchus

Wider, shorter, and straighter primary bronchus; most common site for inhaled objects to lodge.

Lung Stroma

Elastic connective tissue that allows lungs to expand and recoil during breathing.

Respiration (Overall Function)

Supply the body with oxygen and dispose of carbon dioxide through gas exchange.

Inspiration

Process in which diaphragm and external intercostals contract, thoracic volume increases, and intrapulmonary pressure falls below atmospheric pressure.

Expiration

Passive process in quiet breathing where inspiratory muscles relax, thoracic volume decreases, intrapulmonary pressure rises, and air flows out.

Vital Capacity (VC)

Largest respiratory volume; TV + IRV + ERV (≈ 4,100 ml men, 3,100 ml women).

Tidal Volume (TV)

Volume of air moved in normal quiet breathing (~500 ml).

Dead Space Volume

Portion of TV (~150 ml) that remains in conducting zone and does not reach alveoli.

Alveolar Ventilation

Approximately 350 ml of a 500-ml tidal breath that actually reaches alveoli for gas exchange.

Pneumothorax

Collapsed lung caused by air entering pleural space, often from chest wall penetration or rib fracture.

Diffusion (Gas Transport)

Passive cellular transport mechanism that moves O₂ and CO₂ between blood and tissues.

Bicarbonate Ion (HCO₃⁻)

Major form in which CO₂ is transported in the blood.

Cyanosis

Bluish discoloration of skin, mucosae, and nail beds due to inadequate oxygen delivery.

Medulla Oblongata (Respiratory Center)

Brain region that sets basic respiratory rate and rhythm.

Hypercapnia

Elevated blood CO₂ that lowers pH and powerfully stimulates increased rate and depth of breathing.

Chronic Obstructive Pulmonary Disease (COPD)

Progressive airflow limitation disease; includes chronic bronchitis and emphysema.

Emphysema

COPD subtype characterized by alveolar destruction, loss of elasticity, and barrel chest; makes exhalation difficult.

Surfactant

Fatty substance produced by type II alveolar cells that reduces surface tension and prevents alveolar collapse.

Infant Respiratory Distress Syndrome (IRDS)

Condition in premature newborns caused by insufficient surfactant, leading to alveolar collapse after each breath.

Pleural Membrane Adhesion

Surface tension between visceral and parietal pleura that helps prevent lung collapse.

Residual Volume (Aging Change)

Air remaining in lungs after maximal exhalation; increases as lung elasticity declines with age.

Alveolar Sac

Cluster of alveoli; part of respiratory zone, not conducting zone.

Internal Respiration

Exchange of gases between systemic blood and tissue cells.

External Respiration

Exchange of gases between alveolar air and pulmonary capillary blood.

Tracheal Cartilaginous Rings

C-shaped hyaline cartilage rings that keep trachea patent while allowing esophageal expansion posteriorly.

Pharyngotympanic (Eustachian) Tubes

Channels that connect middle ears to nasopharynx for pressure equalization and drainage.

Paranasal Sinuses

Frontal, sphenoid, ethmoid, and maxillary cavities that produce mucus draining into nasal cavity, aiding filtration and resonance.

Respiratory Membrane

Thin barrier of alveolar and capillary walls with fused basement membranes where external respiration occurs.

Expiratory Reserve Volume (ERV)

Additional air (beyond TV) that can be forcibly exhaled after normal expiration.

Nonrespiratory Air Movements

Air movements not involved in gas exchange, e.g., coughing, sneezing, laughing, crying.

Aspiration Site in Children

Right main bronchus is the usual location for inhaled foreign bodies, such as beads.

Involuntary Breathing Override

Brainstem reflexes resume breathing when CO₂ rises or O₂ falls, preventing fatal voluntary breath-holding.