Overview
This lecture introduces the structure and function of the respiratory system, focusing on the anatomy involved in filtering, warming, and transporting air for gas exchange and vocalization.
Functions of the Respiratory System
- Filters incoming air to protect delicate alveoli from particles.
- Exchanges gases by bringing in oxygen and removing carbon dioxide.
- Respiration has five parts: ventilation (breathing), external respiration, transport of gases (via cardiovascular system), internal respiration (capillary exchange), and cellular respiration (ATP production).
Respiratory Anatomy Overview
- Divided into upper (outside thorax) and lower (within thorax) respiratory tracts.
- Upper includes nose, nasal cavity, sinuses, and pharynx; lower includes larynx, trachea, bronchi, bronchioles, alveoli, and lungs.
Upper Respiratory Structure
- Nasal hairs filter large particles; nasal conchae covered in mucous tissue further filter and warm air.
- Nasal cavity lined with pseudostratified ciliated columnar epithelium and goblet cells for mucus production.
- Paranasal sinuses (frontal, sphenoidal, maxillary, ethmoidal) lighten skull, warm/moisten air, and aid sound resonance.
- Hard and soft palate separate nasal and oral cavities; uvula helps seal nasal cavity when swallowing.
- Pharynx (throat) has three regions: nasopharynx, oropharynx, laryngopharynx—common pathway for air and food.
Lower Respiratory Structure
- Larynx (voice box) contains vocal cords, thyroid cartilage (Adam's apple), cricoid cartilage, and epiglottis.
- Epiglottis covers glottis (vocal opening) when swallowing to prevent aspiration.
- True vocal cords vibrate to produce sound; pitch and intensity depend on cord tension and airflow.
- Trachea (windpipe) supported by C-shaped hyaline cartilage rings for airway protection and flexibility.
- Carina is the last cartilaginous ring before tracheal split into bronchi.
Bronchial Tree and Lungs
- Bronchi branch into primary, secondary, tertiary bronchi, then bronchioles (lose cartilage), then terminal bronchioles, leading to alveoli.
- Alveoli are tiny, fragile air sacs for gas exchange, surrounded by capillaries for maximum surface area.
- Lungs: right lung has three lobes; left lung has two lobes and cardiac notch for heart.
- Pleura: parietal pleura lines cavity, visceral pleura covers lungs, pleural cavity contains fluid for lubrication.
- Mediastinum is the central space between lungs containing heart, esophagus, and more.
- Hilum is where blood vessels and bronchi enter/exit the lung.
Airway Protection Mechanisms
- Mucus escalator (cilia and mucus) moves trapped particles up to throat to be swallowed/spit out.
- Coughing and sneezing expel irritants from respiratory tract.
- Bronchioles can constrict to prevent particles from reaching alveoli; excessive constriction in asthma causes difficulty breathing.
Key Terms & Definitions
- Alveoli — tiny air sacs in the lungs where gas exchange occurs.
- Ventilation — process of moving air in and out of the lungs (breathing).
- External respiration — exchange of gases between lungs and blood.
- Internal respiration — exchange of gases between blood and tissues.
- Cellular respiration — use of oxygen in cells to produce ATP and carbon dioxide.
- Pharynx — throat; passageway for food, liquids, and air.
- Larynx — voice box containing vocal cords.
- Trachea — windpipe, airway between larynx and bronchi.
- Bronchioles — small airways without cartilage leading to alveoli.
- Pleura — membranes surrounding and protecting the lungs.
Action Items / Next Steps
- Study respiratory and digestive anatomy models in lab.
- Learn locations and functions of nasal cavity, sinuses, pharynx, larynx, trachea, bronchi, bronchioles, alveoli, and pleura.
- Prepare for upcoming quiz covering respiratory anatomy.