The Pathophysiology of Asthma
Topics covered:
The definition of asthma.
The pathological changes in the airway. The three main factors that
change in the asthmatic airway and how this results in remodelling and
damage.
Airway hyper-responsiveness, changes in histamine sensitivity,
responsiveness and threshold.
Factors that trigger an asthmatic attack including common allergens
An outline of the inflammatory response to an allergenic stimulus. The
role of T lymphocytes, eosinophils and mast cells.
The role of neural factors such as irritant receptors and J receptors in
asthma.
How the pathological changes in asthma alter respiration physiology
Poiseuille's law - relating laminar airflow to airway dimensions,
pressure drop along the airway and gas viscosity
Which generations of airway contribute most to airway resistance.
The five main factors which determine airway radius, namely: smooth
muscle tone, radial traction, oedema of the airway wall, mucus in the
airway lumen, and airway compression.
Why the airway may collapse in a forced expiration in asthma.
The equal pressure point (EPP).
Key points
Definition
Pathology
Immunology of asthma
Pathophysiology of airway narrowing
Asthma
Asthma is a condition where there is a lower airway obstruction that reverses either
spontaneously or with treatment. It is a common condition, with around 1 in 5
suffering asthma sometime in life.
There is an immunological basis to most asthma, but not all, there can also be other
components whereby it becomes a multifactorial disease process with genetic,
allergic, environmental, infectious, emotional and nutritional components.
There are a number of components to the pathology of the asthma, including there
being remodelling of the airways, induction of asthmatic state vs triggering of
asthmatic attack. There is also the important element of airway responsiveness.
These can be sort of combined below
, Asthma is an inflammatory disease of the airways, inflammation involves all airway
levels, from the trachea to the bronchioles. Airway obstruction may be caused by one
or all of the following –
Airway smooth muscle contraction
Oedema of airway wall
Accumulation of airway mucus
Asthmatic airways have an abnormal structure, this is shown in the images below –
As can be seen in a normal persons airway the submucosal glands are a normal size,
the submucosa is not oedematous and the cartilage plate is stiff, ASM (airway smooth
Topics covered:
The definition of asthma.
The pathological changes in the airway. The three main factors that
change in the asthmatic airway and how this results in remodelling and
damage.
Airway hyper-responsiveness, changes in histamine sensitivity,
responsiveness and threshold.
Factors that trigger an asthmatic attack including common allergens
An outline of the inflammatory response to an allergenic stimulus. The
role of T lymphocytes, eosinophils and mast cells.
The role of neural factors such as irritant receptors and J receptors in
asthma.
How the pathological changes in asthma alter respiration physiology
Poiseuille's law - relating laminar airflow to airway dimensions,
pressure drop along the airway and gas viscosity
Which generations of airway contribute most to airway resistance.
The five main factors which determine airway radius, namely: smooth
muscle tone, radial traction, oedema of the airway wall, mucus in the
airway lumen, and airway compression.
Why the airway may collapse in a forced expiration in asthma.
The equal pressure point (EPP).
Key points
Definition
Pathology
Immunology of asthma
Pathophysiology of airway narrowing
Asthma
Asthma is a condition where there is a lower airway obstruction that reverses either
spontaneously or with treatment. It is a common condition, with around 1 in 5
suffering asthma sometime in life.
There is an immunological basis to most asthma, but not all, there can also be other
components whereby it becomes a multifactorial disease process with genetic,
allergic, environmental, infectious, emotional and nutritional components.
There are a number of components to the pathology of the asthma, including there
being remodelling of the airways, induction of asthmatic state vs triggering of
asthmatic attack. There is also the important element of airway responsiveness.
These can be sort of combined below
, Asthma is an inflammatory disease of the airways, inflammation involves all airway
levels, from the trachea to the bronchioles. Airway obstruction may be caused by one
or all of the following –
Airway smooth muscle contraction
Oedema of airway wall
Accumulation of airway mucus
Asthmatic airways have an abnormal structure, this is shown in the images below –
As can be seen in a normal persons airway the submucosal glands are a normal size,
the submucosa is not oedematous and the cartilage plate is stiff, ASM (airway smooth
