(Mostly) Physiology
Explain how volume and pressure change (increase or decrease) throughout both inspiration and expiration
Inspiration: Diaphragm contracts, thoracic cage expands → Volume ↑, Pressure ↓
Expiration: Diaphragm relaxes, thoracic cage contracts → Volume ↓, Pressure ↑
Which lung(s) contain(s) both a horizontal and an oblique fissure? Both, left, or right?
right
Explain the difference between a pneumothorax and a pleural effusion
Pneumothorax is air in the pleural space → lung collapses.
Pleural effusion is fluid in the pleural space → lung gets compressed.
Both impair breathing, but one is air, the other is fluid.
What is the name of the disease associated with the following:
Inhalation of coal dust particles which triggers an immune reaction
Accumulates along lymphatics and lymphoid tissues
Can be seen in smokers, and non-smoking urban dwellers
Coal Miner's Lung
What is a spirometer? What is at least one thing it tells us?
A spirometer is a device that measures lung function; it tells us values like:
Vital Capacity (VC)
Forced Vital Capacity (FVC)
Forced Expiratory Volume in 1 second (FEV₁)
FEV₁/FVC ratio
Total Lung Capacity (TLC)
Residual Volume (RV)
Explain the impact of decreased ventilation of arterial blood gas (including acid-base)
ChatGPT said:
Decreased ventilation leads to:
↑ PaCO₂ (hypercapnia)
↓ PaO₂ (hypoxemia)
Respiratory acidosis (due to CO₂ buildup → ↑ H⁺)
Explain the difference in function between type i and type ii pneumocytes
Type I pneumocytes: Thin, flat cells → form 95% of alveolar surface → main role is gas exchange.
Type II pneumocytes: Cuboidal cells → secrete surfactant to reduce surface tension and regenerate both cell types after injury.
What is the fancy medical term for an occupational lung disease
pneumoconiosis
Name at least one clinical feature commonly associated with obstructive lung diseases. (besides dyspnea)
Wheezing
Chronic cough
Hyperinflated chest (barrel chest) in advanced cases like COPD
Prolonged expiration
Explain what the bohr effect is.
CO2 produced by metabolism generates H+ in RBCs
H+ and low pH trigger release of O2 by hemoglobin
Deoxyhemoglobin has a high affinity for H+
In low O2 areas, H+ binds hemoglobin
Causes Hgb to release more oxygen (right shift)
Which zone of the lung (1,2 or 3) has the lowest V/Q ratio?
Zone 3 has the lowest V/Q ratio.
Perfusion (Q) is highest due to gravity
Ventilation (V) is also high, but not as much as perfusion → V/Q ↓
The bronchial artery carries blood with a higher oxygenation level than the pulmonary artery.
Why:
Bronchial artery comes from the aorta → carries oxygenated systemic blood to nourish lung tissue.
Pulmonary artery comes from the right ventricle → carries deoxygenated blood to the lungs for gas exchange.
Which pathology is characterized by reversible airway obstruction and mixed inflammatory infiltrate (especially eosinophils)?
Asthma
Which category of lung diseases contain a markedly reduced FEV1/FVC ratio? Name one example of a disease in this category.
Obstructive Lung Diseases
FEV₁ (forced expiratory volume in 1 sec) is reduced more than FVC due to airflow limitation
This leads to a lower ratio (<70%)
What is the mechanism of action of albuterol? Be specific to receptor
Albuterol is a β₂-adrenergic receptor agonist.
Binds to β₂ receptors on bronchial smooth muscle
Leads to smooth muscle relaxation → bronchodilation
Name at least 3 factors that cause a leftward shift in the hemoglobin-oxygen dissociation curve
↓ CO₂ (hypocapnia)
↓ H⁺ (alkalosis / ↑ pH)
↓ Temperature
↓ 2,3-BPG
Fetal hemoglobin (HbF)
Carbon monoxide (CO) poisoning
Explain the placement of the pulmonary artery in the left lung vs the right lung (in reference to the bronchus)
Right lung:
Pulmonary artery is Anterior to the bronchus
→ "RALS" = Right = Anterior Left lung:
Pulmonary artery is Superior to the bronchus
→ "RALS" = Left = Superior
What type of cancer is associated with asbestosis (inhalation of asbestos)?
1. Mesothelioma
A rare cancer of the pleura (lining of the lungs)
Strongly associated with asbestos exposure
Not linked to smoking
Which disease is classically associated with hilar lymph node involvement and is often mistaken for tuberculosis? What is the expected FEV₁/FVC ratio in this disease?
Sarcoidosis is classically associated with bilateral hilar lymphadenopathy and is often confused with tuberculosis due to similar chest imaging and granuloma formation.
FEV₁/FVC ratio in sarcoidosis is typically normal or increased
→ Because sarcoidosis is a restrictive lung disease, both FEV₁ and FVC are reduced, but proportionally.
Explain one factor that causes pulmonary vasoconstriction, and why this is physiologically significant
One key factor that causes pulmonary vasoconstriction is low alveolar oxygen (hypoxia). Known as hypoxic pulmonary vasoconstriction (HPV):
When an alveolus has low O₂, nearby arterioles constrict to redirect blood flow to better-ventilated areas, optimizing gas exchange.
Unique to lungs: in most other tissues, hypoxia causes vasodilation.
What kind of epithelium lines the respiratory units/ airways of the respiratory system? Is it ciliated? Why or why not?
Simple Squamous Epithelium, not ciliated to maximize gas exchange.
What is the name of the most distal portion of the conducting zone of the respiratory system?
The terminal bronchioles
Terminal bronchioles mark the end of the conducting zone, no gas exchange occurs here.
Beyond them begins the respiratory zone (starting with respiratory bronchioles), where gas exchange starts.
COPD is characterized by two distinct underlying pathologies. What are they?
Chronic bronchitis – inflammation of the airways with excess mucus production
Emphysema – destruction of alveolar walls → loss of elastic recoil and air trapping
Both cause airflow obstruction, but through different mechanisms.
Explain the pathophysiology of cystic fibrosis (the direction of ion transport in a healthy airway, which channel is defective in CF, and how this defect leads to disease)
In healthy airways:
The CFTR channel (apical membrane) secretes Cl⁻ into the airway lumen
The ENaC channel reabsorbs Na⁺ from the lumen
Water follows ions, keeping mucus thin and easily cleared
In cystic fibrosis:
The CFTR channel is defective → ↓ Cl⁻ secretion
ENaC becomes overactive → ↑ Na⁺ reabsorption
Water follows Na⁺ back into cells → dehydrated, thick mucus
Result:
Thickened secretions, poor mucociliary clearance
At birth, the pressure between the right and left sides of the heart shifts. Which side has higher pressure before and after birth, and why is this change important?
Before birth: Right heart pressure > Left (due to high pulmonary resistance from collapsed lungs)
After birth: Left heart pressure > Right (lungs expand → ↓ pulmonary resistance → ↑ left atrial return)
Importance: This pressure shift closes fetal shunts (e.g., foramen ovale) → enables normal postnatal circulation and lungs to receive blood