Respiration I Flashcards
What is laminar flow
flow of a fluid when each particle follows a smooth path
What is flow type governed
determination of flow type
Describe the alveolar pressure during expiration
alveolar pressure is greater than atmospheric pressure
Under laminar conditions what is flow rate proportional to
the pressure gradient
Where does maximum rate of flow occur
centre of a tube
What is turbulent flow rate proportional to
square root of the pressure gradient/difference
TRUE or FALSE - in most places of the lung air flow is laminar
FALSE
What do you need to achieve a set flow rate under turbulent conditions
greater pressure gradient
Describe the relationship between flow rate and pressure under laminar conditions
positive linear correlation
Under what circumstances do eddies develop
when turbulent air hits branching points
Describe transitional flow
when air becomes turbulent then returns to being laminar
Where is cross sectional area of the airways high
respiratory zone
Why does the respiratory zone have high cross sectional area
branches
Describe the relationship between velocity and cross sectional area
velocity decreases as cross sectional area increases
What is the normal flow type at high velocity
turbulent
Name some factors reducing airway diameter
inflammation, increased mucous production, oedema
What is COPD
progressive lung diseases characterised by increased airway resistance and decreased airflow
Examples of COPD
Chronic bronchitis, emphysema
Describe chronic bronchitid
long term inflammation of bronchi and bronchioles
Describe emphysema
destruction of alveoli walls
True or False - There is a cure for emphysema
false
What are gluco-corticosteroids used for
reduce background inflammation and maintain decent air flow
Why do the airways become floppy in emphysema
loss of elastic nature
What can be used to manage COPD
gluco-corticosteroids, and bronchodilators
What are bronchodilators
anti-cholinergics or B2 adrenoreceptor agonists
Example of beta 2 adrenoreceptor agonist
salbutamol
What is Poiseuille’s law
Airway resistance is proportional to gas viscocity and the length of the tube
What is airway resistance inversely proportional to
fourth power of the radius
What is the difference in airway resistance in COPD
huge resistance in small airways compared to normal.
What is oedema
increased fluid retention in the lungs
Describe the pressure in the alveoli at the end of normal respiration
same as barometric pressure
describe the pressure in the intrapleural space at rest
sub atmospheric
What happens if alveolar and intrapleural pressure are equal
collapsed lung
What is transmural pressure
difference in pressure between two sides of a wall
Where is the maximum pressure gradient in the lungs during inspiration
alveoli
What is the net effect of the transmural pressure during inspiration
airway expansion
What is the value of transmural pressure during inspiration
positive
What is the effect of transmural pressure during inspiration
causes airway expansion, therefore decreasing the resistance
How can patients with emphysema overcome airway collapse
exhale through pursed lips or expire slowly
Describe the relationship between lung volume and airway resistance
as lung volume increases, airway resistance reduces
When is airway resistance highest
small lung volume
Describe the relationship between resistance and inflation
when resistance is increased inflation is impaired
Under what time constant do lungs inflate rapidly
small time constant
What is the time constant under normal conditions
low time constant
Describe the time constant in COPD
increased, lungs dont inflate as quickly
