Anatomy and Physiology of the Respiratory System

1. Structure of the Respiratory System a. Mediates the uptake of O2 needed for metabolism - Process of Ventilation b. Pathway: i. Air enters - Nasal Opening - Nasal Cavity - Pharynx - Trachea - R/L Bronchus - R/Bronchus: Right Lung (3 Lobes) - L/Bronchus: Left Lung (2 Lobes) - Bronchioles - Alveoli - thin walled strx, site of gas exchange, covered in Surfactant - medium for gas exchange, keeps lung from collapsing by maintaining surface tension 2. Interactions of the Circulatory and Respiratory System a. Heart located in chest - mainly left side. This allows the right lung more space (Superior/Middle/Inferior) Left (Superior/Inferior) - separated by Bronchopulmonary Segments. Key: each segment receives air from its own bronchus and blood from its own artery b. Each lobe is contained within a double protective membrane called Pleura which is surrounded by pleural fluid. Lungs located in thoracic cavity. c. Blood/O2 diffusion happens where capillaries of the circulatory system interact with alveoli of the lungs 3. Fx’s of the Respiratory System a. Gas exchange in the lung occurs by diffusion (passive transport mechanism). The rate of diffusion is - DIRECTLY PROPORTIONAL - to the surface area involved and the [ ] gradient. INVERSELY PROPORTIONAL - to the distance between two solutions. b. Ventilation Occurs - as a combination of muscle action and negative pressure. i. The Diaphragm/Intercostal Muscles - contract simultaneously to INCREASE VOLUME in the lungs. This decreases pressure in lungs - DRAWS IN AIR. Diaphragm/Intercostal Muscles - relax causing a reduction in lung volume and causing air to be pushed out. ii. Tidal Volume - the amount of air breathed in and out the lungs iii. Residual Capacity - small amount of air rich CO2 remains trapped in alveoli after expiration and mixes with the air rich O2 brought in through inspiration iv. This is regulated by Medulla Oblongata - controls respiration by monitoring CO2 levels and pH of Blood 1. I.e. if pH of blood decreases then respiration rates will increase c. Factors Affecting the Respiratory System i. Asthma - airways of respiratory system narrow 1. Results from: swelling of the airways or from mucus buildup, make it difficult to inhale and exhale normal amounts of air. Leads to SOB, Diff breathing, wheezing. ii. Environmental Pollutants - smoke, pollen, chemicals can damage Cillia - which cleans particles in the lungs. Damage Cillia can lead to to Emphysema. iii. Lung Surfactant Insufficiency, Asthma, Cystic Fibrosis - hereditary disease that affects the lungs and digestive system. The body produces thick and sticky mucus that can clog the lungs and obstruct the pancreas. iv. Pathogens - Influenza, Tuberculosis and Pneumonia. 1. Influenza - effects nasal cavity, trachea, bronchi, lungs 2. Tuberculosis - infection destroys patients' lung tissue, causing them to cough up the bacteria, which then spread through the air