Pathology of Lung disease Flashcards
What is the difference between resistance and Compliance?
Resistance - ease at which gas flows through conducting airways. (opposition to movement of blood through the airway).
Compliance- Expandability of the lungs and chest wall.
Elastance is a measure of the rebound of the lungs after it has been stretched by inhalation(ease of rebound).
- Compliance and elastance are inversely related to each other e.g when high compliance , low elastance vise versa. e.g Rubber band - when resting it has high compliance (can be stretched a lot - when stretched it has low compliance by high elastance/recoil.
Conductance - The amount of air reaching the alveoli per unit of time per unit of pressure. (reciprocal of resistance)
What disease does increasing resistance link to ?
Obstructive lung disease - narrowing of airways etc - harder for air to flow through conducting airways.
What disease does decreasing compliance link to ?
Restrictive lung disease - Cannot fully expand the chest- so, Compliance, expandability of the chest wall decreases.
What is a wheeze?
Caused by airway obstruction at the level of the bronchioles, increasing resistance.
CHARACTRISTICS- narrowing of airways, high pitched whistling noise when breathing out.
- Caused by inflammation/ smooth muscle spasm.
- Situated inside of the thoracic cavity
- Narrowing worsens during expiration, as it increases the positive intrapleural pressure, compressing small intrathoracic pressure further and limiting expiratory flow.
Can you hear a wheeze during inspiration?
Inspiration - external ICM pull ribs outwards helping the widen the narrowing.
What is Stridor?
Caused by airway obstruction at the outside of the Thoracic cavity at the Larynx or Trachea.
- Caused by tumours, infection and swelling or foreign body.
High pitch Grating noise -
During inspiration, pressure in the thorax decreases as volume of the chest increases, air rushes in. This narrows the obstructed part of the airway.
Can you hear Stridor during expiration?
No, Expiration the volume of the thorax decrease, so pressure increase(positive pressure - a pressure within a system than is greater than its environment), so air moves out of the lungs. This helps to increase the upper airway diameter improving air flow.
What classes of drugs treat obstructive lung disease?
ANTI - INFLAMMATORY DRUGS
- Steriods/ Corticosteriods
- Leukoktriene Antagonists (Bronchoconstriction preventors )- block chemical reaction that leads to inflammation in the airways.
ANTIBIOTICS
- if infection present
BRONCHIAL SM DILATORS
via the autonomic nervous system.
e.g Salbutamol - beta 2 agonist - stimulates the beta 2 receptors causes muscles in airways to relax - airways open.
- Ipratropium - Anti -cholinergic effect - blocks the cholinergic nerves that causes the muscles to relax and airways to dilate.
blocks acetylcholine.
What is Emphysema?
Walls of Alveoli destroyed , creating large air space - reducing surface area for Gas exchange - elastic recoil reduced due to connective tissue damage.
smoked induced emphysema - characteristically centri - acinar (located centrally), (peri-acinar - located near the perimeter).
What is Pneumonia ?
Acute infection - produces toxins and inflammatory reaction. Alveoli become filled with debris reducing normal gas exchange.
What is Asthma?
Smooth muscle spasms, increased mucus secretion contributes to airway obstruction. Necrosis of bronchial cells can occur.
what is Bronchiltis?
Inflammation associated with excessive and thick mucus production- narrowing airways and reducing cillary function.
Fibrosis
Membranes thicken leading to increased diffusion distance also scarring ( usually as a result of injury)
