Intro To Respiratory System Flashcards
Tidal volume
The amount of gas drawn into the lungs at each breath
Boyle’s law
Pressure exerted by a gas is inversely proportional to the the volume it occupies in a closed system. If the volume decreases the pressure will rise
Respiratory rate
the number of breaths per minute
Minute volume
Total ventilation in one minute tidal volume x respiratory rate
Blood supply to the airways
Branching blood vessels from the bronchial circulation form a network that runs with the bronchial tree and lymphatics down to the terminal bronchioles. Beyond this, blood supply is from the pulmonary circulation.
What is a terminal bronchiole?
A bronchiole at the end of the conducting zone of the airway, beyong the walls of the bronchi have no cartilage and have smooth muscle walls.
Conducting airway
Starts from the trachea to the terminal bronchi. The trachea subdivides into left and right main bronchi which then subdivides further.
Conducting airways do not take part in gas exchange. Each bronchiole is connected via respiratory bronchioles and alveolar ducts to the alveoli. The whole airway system acts as a mechanism of getting gas to the alveoli.
Why do asthmatics have an expiratory wheeze?
The walls of the respiratory bronchioles are formed from smooth muscle have no cartilage. This allows them to increase and decrease in size with ventilation.
In asthmatics there is increased resistance to flow of gas, causing a wheeze.
In patients with COPD, airways constrict at the wrong time, causing air trapping.
What determines the final gas content in the blood at equilibrium?
Affinity for Hb
Solubility of the gas in plasma
Gas tension
Plasma dissolves oxygen, because oxygen has a low solubility in plasma (small percentage). Whole blood contains Hb which has a high affinity for oxygen. This provides the main form of oxygen transport.
Anatomical dead space
Areas of the airway that are not involved in gas exchange (conducting airway) i.e. nose and mouth, pharynx, larynx, trachea, brochi>terminal bronchioles.
This is the first volume of gas to leave the lungs during expiration and has the same composition as atmospheric air
Ventilation
The flow of air in and out of the respiratory system in a given time.
Physiological dead space
Sum of the distributive and anatomical dead space
Distributive dead space
Occurs where ventilation does not match perfusion in the lung so efficient gas exchange cannot occur. If an area of the lung is not perfused, then no gas exchange can take place.
FEV1
Volume of air that can be forcibly blown out in 1 second after full inspiration
FVC
Volume of air that can be forcibly blown out following full inspiration
