phase 1 week 8 Flashcards
What is a cough?
An explosive expiration that provides a normal protective mechanism for clearing the tracheobronchial tree of secretions and foreign material
What may initiate the cough reflex?
excessive amounts of foreign matter or other causes of irritation
What forms the afferent limb of the cough reflex?
receptors within the sensory distribution of the trigeminal, glossopharyngeal, superior laryngeal and vagus nerves
What forms the efferent limb of the cough reflex?
the recurrent laryngeal nerve and the spinal nerve
Describe that caught reflex?
about 2.5 litres of air is inspired
epiglottis closes, vocal cords tightly shut to entrap the air within the lung
abdominal muscles contract forcefully, pushing against the diaphragm
internal intercostal muscles contract forcefully
pressure in lungs rises to 100mmHg or more
Markedly positive intrathoracic pressure causes narrowing of the trachea
vocal cords and epiglottis suddenly open widely
the large pressure difference between the airways and the atmosphere paired with tracheal narrowing produces rapid flow rates through the trachea
At what speed is air expelled from the lungs in a cough?
75-100mph
What are some factors that contribute to asthma?
environmental alleges viral respiratory tract infections exercise, hyperventilation gastro-oesophageal reflux disease chronic sinusitis aspirin or NSAID hypersensitivity beta blockers obesity occupational exposure emotional factors exposure to tobacco smoke
Describe the pathophysiology of asthma
It is complex and involves the following components;
airway inflammation
intermittent airflow obstruction
bronchial hypersensitivity
Describe airway inflammation
varying degrees of mononuclear cell and eosinophil infiltration, mucous hyper secretion, desquamation of epithelium, smooth muscle hyperplasia and airway remodelling are present
What are the main cells thought to be involved in airway inflammation?
mast cells eosinophils epithelial cells macrophages activated T lymphocytes
What are the main cytokines thought to be involved in airway inflammation?
IL-4, IL5, IL-6, IL-9, IL-13
What is the theory about TL1 and TL2 lymphocytes?
loss of balance between the cells types. In asthma TL2 is favoured - perhaps due to lack of infection exposure?
What causes airflow obstruction in asthma?
acute bronchoconstriciton
airway oedema
chronic mucous plug formation
airway remodelling
Describe the early asthmatic response
Response to aeroallergens
IgE dependent mediator release leads to acute bronchoconstriciton
Describe the late asthmatic response
airway oedema 6-24 hours after allergen exposure
What causes chronic mucous plug formation?
exudate of serum proteins and cell debris
what causes airway remodelling?
long-standing inflammation - may reduce the reversibility of the obstruction
What does airway obstruction cause?
Increased resistance to airflow and decreased expiratory flow rates
the changes lead to decreased ability to expel air and may result in hyperinflation
What does bronchial hyper responsiveness lead to?
bronchospasm and typical asthmatic symptoms such as
wheezing, shortness of breath and coughing
What can bronchospasm be a response to?
allergens environmental irritants viruses cold air exercise
What are the non-pharmacological management options for asthma?
smoking cessation
weight loss
breathing exercises
What are the pharmacological management options for asthma?
inhaled corticosteroids
long acting B2 agonist
short acting B2 agonist
How is complete control of asthma defined?
no daytime symptoms no night time awakening due to asthma no need for rescue medication mo asthma attacks no limitations on activity normal lung function minimal side effects from medication
What are the histological differences in asthma?
increase mucous production and increase goblet cells
increase eosinophils in mucous and cell tissue
thickened basement membrane
increased mast cells in lamina
increased neutrophils and T cells
smooth muscle hypertrophy
