Intro to resp Disease Flashcards
What is asthma?
- Reversible inc in airway resistance, inv broncho-constriction and inflammation
- Decreases in the FEV1 (FEV1- forced expiratory volume in first second)
- Value of < 70% suggests inc airway resistance. If it is asthma this should be rev by B2-adrenoceptor agonist.
- Affects 5-10% of the population
What is COPD?
- Comprises both chronic bronchitis+emphysema
- Airflow limitation that is not fully reversible
- Loss of lung function
- 80-90% of deaths related to smoking
- Typically disease of late onset
- By 2020, projected to be 3rd leading cause of death worldwide
Explain why changes FEV1:FVC are bad.
- Decreases in FV1:FVC ration (FVC-Forced vital capacity) lead to inability to expel air quickly
What are the severity levels of COPD?
Mild:
1. FEV1 80% of predicted–Smokers cough/little to no breathlessness
Moderate:
1. 50-79%–Breathless on moderate exertion
Severe:
1. 30-49%–Breathless at rest/mild exertion. Usually with wheeze and cough
Very severe:
1. < 30%
Prognosis depends on severity.
Genrally poor with progressive deterioration
What are epithelial cells?
- Cilia
- Mucous-secreting goblet cells
- Epithelial cells
- Smooth muscle cells
- Mucous traps particles and the cilia help to move these particles out of the lung (cystic fibrosis has thich mucus)
What pathways are involved in the innervation of the airways?
- Sympathetic
- Parasympathetic
- Sensory
How is the sympathetic pathway involved in the innervation of the airways?
- Circulating adrenaline
- Act on B2-adrenoceptors on bronchial smooth muscle to cause relaxation
- Inhibition of mediator release from mast cells
- B2-adrenoceptors also on mucous glands to inhibit secretion
- Inc clearance of mucous
How is the Parasympathetic pathway involved in the innervation of the airways?
- Release Acetylcholine (ACh)
- Activates muscarinic M3 receptors
1. Bronchoconstriction
2. Inc mucous secretion
How are sensory nerves involved in the innervation of the airways?
- Local reflexes, respond to irritants
- Cause coughing. bronchoconstriction and inc mucous secretion
- Up-regulated by inflammation-are sensory nerves hypersen in asthmatics?
- Potential role in asthma-ind cough, excercise ind asthma, cold-ind asthma
- Capsaicin-ind cough
- Capsaicin acts on TRPV1 receptors to activate sensory nerves
What are the subtypes of Adrenoreceptors?
- B1-e.g. SAN and ventricles in heart- rate and force of contraction
- B2-e.g. airway smooth muscle-relaxation
- B3-e.g. skeletal muscle, adipose tissue
why do we need selectivity in drugs and how is this achieved?
- Allow drugs to affect specific receptors
- Adding an extra mthyl group to Non selective noradrenaline achieves Isoprenaline which is B-adrenoceptor selective
- Then Adding a slightly larger (CH3) group gets salbutamol makes it B2 adrenoceptor selective.
- Salmeterol is a long acting B2 adrenoceptor, has a long lipid tail attached to NH2 group.
- Tail keeps it stuck in membrane allowing it to act on the area for longer
What are catecholamines?
- Me group added to noradrenaline causes deactivation of drugs.
- Extra C on that change by salbutamol stops this being an issue.
Explain Asthma. (Describe)
- Airway inflammation–mast cells and neutrophils
- Inc vascular permeability
- Thinning (desquamation) of airway epithelial layer
- Build up of mucus due to activation of goblet cells
- Remodelling of airways including inc smooth muscle, thickening of luminal basement membrane
What are the phases of an asthmatic attack?
- Bronchoconstriction is Early phase
1. This is caused by Histamine PGD2, LT C4 and LTD4 release - Release of chemokines and cytokines leading to leukocytes is the late phase.
- ^ T-cells, neutrophils, Basophils.
What are the two types of asthma therapy?
- Relief of symptoms-Bronchodilators
(Blocks early phase of asthma attack casued by bronchosonstriction) - Prevention of attack–Anti-inflammatory agents
(Prevents late phase caused by release of cytokines)
