Respiratory Physiology Flashcards
What is the significance of respiratory and cardiovascular systems being closely linked together?
Pathologies of these systems are closely related.
Why are we breathing?
We breathe to produce energy via cellular respiration (by delivering O2 to cells) and to remove CO2, which is a waste product of cellular respiration & build up is toxic to us.
What is the difference between pulmonary and systemic circulation?
Pulmonary circulation involves blood travelling through the pulmonary artery and pulmonary vein. It delivers CO2 to the lungs and picks up O2.
Systemic circulation moves blood throughout the body with the exception of pulmonary circulation. It delivers O2 to the tissues and collects CO2.
Where does gas exchange occur?
It occurs at 2 points. External respiration occurs in the lungs, where O2 diffuses into blood and CO2 diffuses into the alveolar air – it requires integration of respiratory and cardiovascular systems (increased demand of muscles increases the need for substrate acquisition, waste disposal etc). Internal respiration occurs in metabolising tissues where O2 diffuses out of the blood and CO2 diffuses out of the cells.
In a steady state, what is the net volume of gas exchanged in the lungs per unit time?
250 mL/min of O2
200 mL/min of CO2
What is the respiration rate (RR) at rest? How high can it get at max exercising capacity in adults?
at rest -12-18 breaths / min
at max exercising capacity in adults - 40-45 breaths / min
Why do we prefer breathing by nose when we’re not excreting ourselves?
Nose has cilia and mucous which warm and moisten the air entering through it.
Why do we breathe through our mouths when we’re exercising?
Nose offers more resistance than mouth, and we’re already exercising so we want to make breathing as easy as possible.
When is the distinction between upper respiratory tract (URT) and lower respiratory tract (LRT) important?
In pathology, as certain conditions affect only one part of respiratory tract and not the other.
How does air travel through the respiratory tract?
nose/mouth ➡️ pharynx ➡️ larynx ➡️ trachea ➡️ primary bronchus ➡️ secondary bronchus ➡️ … ➡️ bronchiole ➡️ alveoli
Where is cartilage present in the respiratory tract?
Up to bronchi, all tubes are semi-rigid — patency maintained by C-shaped rings of cartilage.
How is the patency of bronchioles maintained?
Bronchioles have no cartilage — patency maintained by physical forces in thorax.
How many divisions are there in the LRT?
~ 24
Where is there most resistance to air flow in the LRT?
conducting zone — less cross-sectional area covered by trachea than by bronchioles
Think of it like when you drive on a narrow empty road and how fast that goes vs driving on a dual carriageway when you enter the city
Can resistance to air flow be altered?
Yes. Resistance to air flow can be altered by manipulation airway diameter by bronchial smooth muscle.
