Overview
This lecture covers the anatomy and primary functions of the respiratory system, focusing on airway structure, filtering mechanisms, gas exchange, and the protective features that keep the lungs safe.
Functions of the Respiratory System
- The main function is breathing: moving oxygen into the body and removing carbon dioxide.
- The system filters incoming air to protect delicate lung tissues (alveoli).
- Respiration involves five parts: ventilation (breathing), external respiration (gas exchange in lungs), gas transport (via cardiovascular system), internal respiration (gas exchange at tissues), and cellular respiration (ATP production).
- Oxygen is needed for cellular respiration to make ATP; carbon dioxide is a waste product that must be removed.
Respiratory System Anatomy
- Divided into upper (above the chest) and lower (within the thoracic cavity) respiratory tracts.
- Upper tract includes nose, nasal cavity, sinuses, pharynx (throat); lower tract includes larynx (voice box), trachea, bronchi, bronchioles, and lungs.
Airway Structure and Function
- Nose hairs, nasal conchae, and sticky mucus filter and warm air.
- Pseudostratified ciliated columnar epithelium with goblet cells lines airways, trapping and moving debris.
- Paranasal sinuses (frontal, sphenoidal, maxillary, ethmoidal) lighten the skull, warm/moisten air, and resonate sound.
Pharynx and Larynx
- Pharynx (throat) is divided into nasopharynx (behind nose), oropharynx (behind mouth), and laryngopharynx (above larynx).
- Larynx contains thyroid and cricoid cartilage, houses vocal cords, and is protected by the epiglottis (prevents food entering airways).
- Vocal cords produce sound by vibration; pitch is controlled by tension and air force.
Trachea, Bronchi, and Bronchioles
- Trachea (windpipe) supported by C-shaped hyaline cartilage rings, preventing collapse.
- Trachea splits at the carina into right and left primary bronchi; bronchi branch into secondary and tertiary bronchi, then into bronchioles.
- Bronchioles lack cartilage and have smooth muscle; terminal bronchioles lead to alveoli.
Alveoli and Gas Exchange
- Alveoli are microscopic air sacs where gas exchange occurs, providing a large surface area (like a tennis court).
- Capillaries surrounding alveoli allow oxygen in and carbon dioxide out.
- Macrophages in alveoli protect against infection.
Lungs, Pleura, and Related Structures
- Right lung has three lobes; left lung has two due to heart placement.
- Each lung is covered by pleural membranes (parietal and visceral pleura) with fluid-filled pleural cavity for lubrication.
- Mediastinum is the space between the lungs; hilum is the entry/exit point for bronchi and blood vessels.
Airway Protection Mechanisms
- Mucociliary escalator (cilia and mucus) moves debris up airways to be swallowed or expelled.
- Coughing and sneezing help expel particles; bronchioles can constrict to trap debris.
- Asthma results from widespread bronchiolar constriction.
Key Terms & Definitions
- Ventilation — breathing (air movement in/out of lungs).
- Alveoli — tiny air sacs for gas exchange.
- Pseudostratified ciliated columnar epithelium — airway lining with cilia and mucus-producing cells.
- Pharynx — throat; common path for air, food, and fluids.
- Larynx — voice box; contains vocal cords.
- Epiglottis — cartilage flap covering trachea during swallowing.
- Trachea — windpipe; main airway.
- Bronchi/Bronchioles — airway branches leading to alveoli.
- Pleura — membranes surrounding lungs.
- Hilum — entry region for vessels/bronchi into organs.
- Mucociliary escalator — mechanism moving mucus and debris out of airways.
Action Items / Next Steps
- Review respiratory and digestive anatomy for the next lab quiz.
- Study anatomical models of respiratory structures in the lab.
- Know the location and function of all highlighted structures.