2. Asthma Flashcards
Name the components that make up the conducting portion of the lungs?
Nostril Nasal Cavities Oral Cavity Pharynx (nasopharynx, oropharynx and laryngopharynx) Larynx Trachea Primary bronchi Secondary bronchi Tertiary bronchi Bronchioles Terminal bronchioles
Name the components that make up the respiratory portion of the lungs?
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Alveoli
Describe the structure of the trachea.
- Wide flexible tube
- Contains 20 tracheal cartilages which are C-shaped rings of hyaline cartilage
- Gap between rings is made up by the trachealis muscle
In the bronchioles, what are the goblet cells replaced by? What function does it perform
Clara cells which secrete surfactant that prevent alveoli collapse
Parasympathetic innervation to the smooth muscle in the walls of the airways causes the muscles to do what?
Causes them to contract, thus the airways narrow
What are type 1 pneumocytes and where are they found?
They are found in the alveoli of the lungs
They are large flattened cells making up 95% of total alveolar area, are they present a very thin diffusion barrier for gases.
What are type 2 pneumocytes and where are they found?
They are found in the alveoli of the lungs.
Despite making up 5% of the total alveolar area, they make up 60% of total number of cells.
They secrete ‘surfactant’ which decreases the surface tension between the thin alveolar walls, and stops alveoli collapsing when you breathe out.
Describe asthma.
Asthma is a chronic inflammatory condition of the airways that causes episodic exacerbations of bronchoconstriction.
In asthma there is reversible airway obstruction that typically responds to bronchodilators such as salbutamol. This bronchoconstriction is caused by hypersensitivity of the airways and can be triggered by environmental factors.
How can asthma be categorised?
- Atopic or Non- Atopic
- Intermittent or Persistant.
Atopic means triggered by the environment, which is most common form. It is mediated by systemic IgE production
Non-atopic is intrinsic, meaning its not caused by exposure to an allergen and is far less common. The inflammation is mediated by local IgE production
What T-helper cell is normally found in the lung? Which one is found in those with asthma? Whats the difference between them?
Normally its T-helper 1, which promotes inflammation by increasing cell mediated immunity.
However in asthma its T-helper 2, which promotes inflammation by increasing humoral immunity (antibody production)
What is the triad of asthma characteristics?
- Smooth muscle contraction
- Smooth muscle hypertrophy
- Mucus hyper-secretion
What are the risk factors of asthma?
- Family history of asthma
- A history of having atopic conditions
- Allergies
- Nasal polyps
- GORD
- Obesity
What are typical triggers for an asthma attack?
- Infection
- Night time or early morning
- Exercise
- Animals
- Cold/damp weather
- Dust / pollen
- Strong emotions
What are the symptoms of asthma?
- Shortness of breath
- Wheeze
- Chest Tightness
- Dry Irritating cough
How is the wheeze in asthma described?
Bilateral widespread “polyphonic” wheeze
According to NICE, how should asthma be diagnosed?
Asthma should never be diagnosed without definitive testing.
First line tests include
- Fractional exhaled nitric oxide (FeNO) - Levels of nitric oxide in breath increases with inflammation. A level over 40 parts per billion (ppb) is a positive test for an adult, and 35 ppb for a child.
- Spirometry with bronchodilator reversibility - A FEV1/FVC ratio of less than 70% is considered as a positive test for obstructive airway disease. These individuals are then offered a bronchodilator. If they have an improvement in FEV1 of 12% or more, plus an increase in volume of 200ml or more, then it’s a positive test.
