Lecture 13 Flashcards
Respiratory System Function
Respiratory system oxygenates blood and removes carbon dioxide
Circulatory System Function
Circulatory system transports gases in the bloodstream
How many lobes are each lung composed of?
The right lung has 3 and the left lung has 2
Bronchi
Largest conducting tube
Bronchioles
Less than 1 mm (thin system of tubes that help conduct air into and out of the lungs)
Terminal bronchioles
Located at the terminus of the conducting zone (last of the conducting airflow in lungs)
Respiratory bronchioles
Distal to terminal bronchiole with alveoli projecting from walls
Alveoli
O2 and CO2 exchange (type
I pneumocytes) have cells that produce surfactant (type II pneumocytes)
Pulmonary Surfactant
Produced by type II pneumocytes. Reduces surface tension in the alveoli
Acinus or respiratory unit
Functional unit of lung (alveoli)
Ventilation
Movement of air into and out of lungs (inspiration and expiration, respectively)
Inspiration
Caused by the action of the diaphragm (descends) and intercostal muscles (expand)
Where does gas exchange occur?
Gas exchange occurs between alveolar air and pulmonary capillaries
What is Atmospheric pressure at sea level?
760 mm Hg
Partial pressure
Part of the total atmospheric pressure exerted by a gas
Partial pressure of oxygen (PO2)
0.20x760mmHg=152mmHg
Why do gases diffuse among blood, tissues, and pulmonary alveoli?
Differences in their partial pressure
Requirements for efficient gas exchange
Changes in atmospheric O2 or CO2, Large capillary surface area in contact with the alveolar membrane, Unimpeded diffusion across the alveolar membrane, Normal pulmonary blood flow, and Normal pulmonary alveoli (Impairment of any will result in impaired gas exchange)
Pleura
Thin membrane covering lungs (visceral pleura) and internal surface of the chest wall (parietal pleura)
Pleural cavity
Potential space between lungs and chest wall
Intrapleural pressure
Pressure within pleural cavity (normally less than intrapulmonary pressure), also referred to as negative or subatmospheric pressure
What does the release of the vacuum in pleural space lead to?
Lung Collapse (loss of negative pressure)
What can impair lung function when found inside the pleural space?
Fluid (inflammatory or hemothorax) or air accumulation (pneumothorax)
Pulmonary Function Tests
Tested by measuring volume of air that can be moved into and out of lungs under normal conditions
Vital capacity
Maximum volume of air expelled after maximum inspiration – can be used to evaluate progress of chronic disease (emphysema)
One-second forced expiratory volume (FEV1)
Maximum volume of air expelled in 1 second – can be used to detect airway narrowing in inflammatory or bronchospasm (Asthma)
Pulse oximeter
Measures oxygen saturation in blood
Pneumothorax
Escape of air into pleural space due to lung injury or disease (Loss of negative pressure)
Manifestations of Pneumthorax
Chest pain, shortness of breath, reduced breath sounds on the affected side, chest x-ray: lung collapse and air in the pleural cavity
Tension pneumothorax
Positive pressure develops in the pleural cavity, and air flows through the perforation into the pleural cavity (air flows on inspiration but cannot escape on expiration which causes a build-up of pressure)
Tension Pneumothorax treatment
Chest tube is inserted into pleural cavity, left in place until lung heals/re-expands
Atelectasis
Collapse of the lung due to obstructive atelectasis or compression atelectasis
Obstructive atelectasis
Thick mucus secretions, tumors, foreign object, diaphragm elevates on affected side