PULMONARY EDEMA
Pulmonary edema is the
accumulation of serous fluid in the alveoli and the interstitial tissue of
lungs.
CAUSES
1. Increased pulmonary capillary
pressure due to left ventricular failure or mitral valve disease
2. Pneumonia
3. Breathing harmful
chemicals like chlorine or sulfur dioxide.
EFFECTS
Effects of pulmonary edema
are severe dyspnea, cough with frothy bloodstained expectoration, cyanosis and cold extremities.
Chronic interstitial edema leads to
asthma. Alveolar edema is fatal and causes sudden death due to
suffocation.
PLEURAL EFFUSION
Pleural effusion is
the accumulation of large amount of fluid in the pleural cavity.
CAUSES
1. Blockage of
lymphatic drainage
2. Excessive transudation
of fluid from pulmonary capillaries
due to increased pulmonary capillary
pressure caused by left ventricular
failure
3. Inflammation of pleural
membrane which damages the capillary membrane, allowing leakage of fluid
and plasma proteins into the pleural
cavity.
FEATURES
Pleural effusion
causes atelectasis, leading to dyspnea and other respiratory disturbances.
PULMONARY TUBERCULOSIS
Tuberculosis is the disease caused by tubercle bacilli. This
disease can affect any organ in the body. However, the
lungs are affected more commonly. Infected tissue is invaded
by macrophages and later it becomes fibrous. Affected tissue is called tubercle.
FEATURES
Initially, alveoli in the affected
part become nonfunctioning, due to thickness of respiratory
membrane.
If a large part of
lungs is involved, the diffusing capacity is very much reduced. In severe conditions,
the
destruction of the lung
tissue is followed by formation of large abscess cavities.
EMPHYSEMA
Emphysema is one of the obstructive
respiratory diseases in which lung tissues are extensively
damaged.
Damage of lung tissues
results in loss of alveolar walls. Because of this, the elastic recoil of lungs
is also lost. Emphysema
is caused by:
1. Cigarette smoking
2. Exposure to oxidant
gases
3. Untreated bronchitis.
DEVELOPMENT OF
EMPHYSEMA
1. Smoke or oxidant
gases irritate the bronchi and bron chioles, leading to chronic infection
2. It increases the mucus CAUSES
1. Blockage of
lymphatic drainage
2. Excessive
transudation of fluid from pulmonary capillaries due to increased pulmonary
capillary
pressure caused by left ventricular
failure
3. Inflammation of
pleural membrane which damages the capillary membrane, allowing leakage of
fluid
and plasma proteins into the pleural
cavity.
FEATURES
Pleural effusion
causes atelectasis, leading to dyspnea and other respiratory disturbances.
PULMONARY TUBERCULOSIS
Tuberculosis is the disease caused by tubercle bacilli. This
disease can affect any organ in the body. However, the
lungs are affected more commonly. Infected tissue is invaded
by macrophages and later it becomes fibrous. Affected tissue is called tubercle.
FEATURES
Initially, alveoli in the affected
part become nonfunctioning, due to thickness of respiratory
membrane.
If a large part of
lungs is involved, the diffusing capacity is very much reduced. In severe conditions,
the
destruction of the
lung tissue is followed by formation of large abscess cavities.
EMPHYSEMA
Emphysema is one of the obstructive
respiratory diseases in which lung tissues are extensively
damaged.
Damage of lung tissues
results in loss of alveolar walls.
Because of this, the
elastic recoil of lungs is also lost.
Emphysema is caused by:
1. Cigarette smoking
2. Exposure to oxidant
gases
3. Untreated bronchitis.
DEVELOPMENT OF
EMPHYSEMA
1. Smoke or oxidant
gases irritate the bronchi and bronchioles, leading to chronic infection
2. It increases the mucus secretion
from the respiratoryepithelial cells causing obstruction of air
passage
3. Cilia of respiratory epithelial
cells are partially paralyzed and the movement is very much reduced.
Because of this, the mucus cannot be
removed from the respiratory passage.
4. Destruction of alveolar mucus
membrane
5. Destruction of elastic tissues occur.
Normally, there is loss of some elastic tissues because of
the proteolytic enzyme called elastase. But, that is
very much negligible. Moreover, liver produces
elastase inhibitors especially, α1-antitrypsin, which prevents the
destruction of elastic tissues.
But, due to heavy
smoking or because of constant exposure to oxidant gases, the pulmonary
alveolar
macrophages increase
in number. Macrophages release
a chemical substance, which attracts a
large number of
leukocytes. Leukocytes release proteases including elastase, which destroy the
elastic tissues of the
lungs.
EFFECTS OF EMPHYSEMA
1. Airway resistance increases several
times due to the bronchiolar obstruction. So, the movement of
air through the respiratory
passage becomes very difficult. It is more pronounced during expiration.
2. Due to the destruction of alveolar
membrane and elastic tissues, the lungs become loose and
floppy.
So, the diffusing capacity
reduces to a great extent. However, lung compliance increases and the aeration
of blood is impaired. Enough oxygen cannot diffuse into blood and carbon dioxide cannot
diffuse out.
3. Obstruction also affects ventilation-perfusion
ratio, resulting in poor aeration of blood
4. Due to the destruction
of lung tissues, the number of pulmonary capillaries also decreases. It increases
the pulmonary vascular resistance,
leading to pulmonary hypertension.
5. Over the years, chronic emphysema
could lead to hypoxia and hypercapnea. It will finally cause
prolonged and severe
air hunger (dyspnea), leading to death.
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