Respiratory

Question 1

Infant respiratory distress syndrome

Answer 1

Cause of V/Q mismatch
Insufficient surfactant produced by premature babies, increases surface tension of lung making inflation more difficult
Can develop pulmonary edema because no surfactant to reduce tendency of fluid pulled in from capillaries by the lower interstitial pressure

Question 2

Pulmonary oedema

Answer 2

An abnormal accumulation of fluid which can flood the alveoli and impair gas exchange
Caused by high capillary pressure, capillary permeability, or alveolar surface tension

Question 3

Sickle cell anaemia

Answer 3

Results form a mutation of the glob in polypeptide
HBs polymerises, especially under conditions where 02 is low or acidity is high (eg respiring tissues) the polymerised protein distorts the shape of the erythrocytes making it sickle-shaped, and causes it to obstruct small capillaries, triggering Sickling crisis

Question 4

Asthma

Answer 4

Cause of V/Q mismatch (temporary obstructive lung disease)
Inflammatory disorder –> episodic constriction of bronchioles –> acute breathlessness, wheezing, cough
Bronchodilators act on B2

Question 5

Emphysema

Answer 5

Destruction of supporting structure of lung by chronic coughing and congested airways (enzymes destroy elastic fibres, as leukocytes reach site of infection) –> decrease elasticity –> increase complinance and airways collapse –> additional effort to exhale required
Trapped air in alveoli –> overinflate the lungs
Obstructive lung disease
Have high lung volumes and abnormally high residual volume

Question 6

Adult respiratory distress syndrome

Answer 6

Diffuse lung injury of various causes including trauma, long bone injury, and pelvic injury, sepsis, aspiration of stomach contents
Decreased lung compliance, pulmonary oedema, focal atelectasis, hypoxemia, inflammatory response –> aggregation of neutrophils causes capillary endothelial damage.

Question 7

Pulmonary embolism

Answer 7

Movement of blood clot from systemic veins through right heart and into pulmonary circulation, lodges in branch of artery
Contributions to venous thrombosis: hypercoagulability; endothelial damage; stagnant blood flow
Raises V/Q ratio –> significant increase in physiological dead space

Question 8

Chronic obstructive pulmonary disease

Answer 8

Chronic obstruction of the small airways
Excessive mucus production (bronchitis)
Airway narrowing by bronchial spasms (asthma)
Airway collapse during expiration (emphysema)

Question 9

Cystic fibrosis

Answer 9

Effects exocrine glands
Causes abnormal secretion of materials
Excessive production of thick (caused by altered mucus proteins), sticky mucus which obstructs
Mutation in Cystic Fibrosis Transmembrane conductance a Regulator (CFTR) prevents Chloride ion flow, and hence water flow too

Question 10

Sleep apnea syndrome

Answer 10

Disruption of breathing during sleep
Obstructive - pharyngeal muscles fail to open, due to decreased muscle active, and increased amounts of fat around neck
Hypoxia and hypercapnea in apnea intervals, may lead to hypertension and myocardial distress

Question 11

Pneumothorax

Answer 11

Collapsed lung
Air is introduced into pleural space because pleural pressure is normally subatmospheric, lung collapsed inward and chest wall outward
Restricts inflation causing hypoxic vasoconstriction, but there is still blood flow
Cause of V/Q mismatch