An individual small airway has much greater resistance than a large airway, however there are many more small airways than large ones. Therefore, resistance is greatest at
the bronchi of intermediate size, in between the fourth and eighth bifurcation
.
Where does most airway resistance occur?
The site of most airway resistance is
the medium-sized bronchi
. The smallest airways contribute very little to resistance, because the combined cross-sectional area of these airways is much larger than that of the intermediate bronchi.
What is the major determinant of resistance to airflow?
length and radius) are the most important determinants of resistance, followed by the
viscosity of the gas
. A maximum flow rate exists; beyond which various eddies and vortices develop, making the flow becomes turbulent. The smaller the calibre of the airway, the lower the flow rate required to produce this effect.
What is the primary resistance airway?
Airway resistance is the resistance to flow of air caused by friction with the airways, which includes the conducting zone for air, such as the trachea, bronchi and bronchioles. The main determinants of airway resistance are
the size of the airway and the properties of the flow of air itself
.
Where in the respiratory system is velocity of air flow highest and lowest?
Based on the total cross-sectional area of different airways, where is the velocity of air flow highest and lowest?
Velocity is highest in the trachea and lowest in the bronchioles
.
What happens when airway resistance is increased?
Bronchospasm, mucus plugging, and edema in the peripheral airways
result in increased airway resistance and obstruction. Air trapping results in lung hyperinflation, ventilation/perfusion (V/Q) mismatch, and increased dead space ventilation.
What is a normal airway resistance?
Airway resistance is the friction caused by the movement of air throughout the respiratory system and conducting airways. In a spontaneously breathing adult, normal airway resistance is estimated at
2 to 3 cm H2O/L/sec.
Which factor has the greatest effect on resistance?
The three most important factors affecting resistance are
blood viscosity, vessel length and vessel diameter
and are each considered below. Blood viscosity is the thickness of fluids that affects their ability to flow.
What are the three important sources of resistance to blood flow?
There are three important sources of resistance:
vessel length, blood viscosity, and vessel diameter
. Let’s discuss blood vessel length first.
What increases resistance to circulation?
Numerous factors can alter resistance, but the three most important are vessel length, vessel radius, and
blood viscosity
. With increasing length, increasing viscosity, and decreasing radius, resistance is increased.
What are the factors that affect airway resistance?
Multiple factors can influence airway resistance, including
airflow velocity, the diameter of the airway, and lung volume
. These are some of the most significant contributing factors and will be discussed further on how these variables exert change and why this is important for managing patient airways.
Where in his airway The resistance is highest and why?
Resistance is highest in
the medium-sized conducting airways
and lower in the large airways because of their large diameters. As the air travels into the medium-sized bronchi, it faces greater resistance due to the drop in diameter of the airway.
What are some diseases that could affect airway resistance?
- Mechanical obstruction or compression. Extrinsic, eg. by tumour. …
- Decreased internal crossection. Oedema. Mucosal or smooth muscle hypertrophy. …
- Decreased smooth muscle tone. Bronchodilators. Sympathetic nervous system agonists.
- Increased smooth muscle tone. Bronchospasm.
What is the order of airflow through the respiratory system?
The air that we breathe in enters the nose or mouth, flows through
the throat (pharynx) and voice box (larynx)
and enters the windpipe (trachea). The trachea divides into two hollow tubes called bronchi.
Does bronchodilation increase air flow?
Heliox is often an adjunctive therapy alongside albuterol for reducing airway resistance. With severe airway narrowing, gas velocity increases, and airflow becomes turbulent. This
turbulent airflow increases airway resistance
.
What is the order of airflow during inhalation?
When you inhale through your nose or mouth, air travels down the pharynx (back of the throat),
passes through your larynx (voice box) and into your trachea (windpipe)
. Your trachea is divided into 2 air passages called bronchial tubes. One bronchial tube leads to the left lung, the other to the right lung.
