Lecture 18 Flashcards
Why does oxygen availability decrease at high altitudes if the percentage of oxygen in the air remains the same?
Because barometric pressure decreases, reducing the partial pressure of oxygen (PO₂) in the air. This means fewer oxygen molecules enter the lungs with each breath.
What happens to alveolar PO₂ at 30,000 feet?
It drops to 30 mmHg, which is much lower than normal, even with compensatory mechanisms.
At what hemoglobin saturation level does a person typically lose consciousness?
Around 50% hemoglobin saturation.
What are two key short-term (acute) adaptations to high altitude?
Increased respiratory rate (RR) to bring in more oxygen.
Decreased CO₂ levels (hypocapnia), which can lead to respiratory alkalosis.
What are three long-term adaptations to high altitude?
Increased erythropoietin (EPO) release, which stimulates red blood cell (RBC) production.
Increased capillary density to improve oxygen delivery to tissues.
Increased lung diffusion capacity to enhance gas exchange efficiency.
What is the main cause of High-Altitude Pulmonary Edema (HAPE)?
Low oxygen causes pulmonary vasoconstriction, increasing capillary pressure and leading to fluid buildup in the lungs.
What are the symptoms of High-Altitude Cerebral Edema (HACE)?
Brain swelling causes headache, weakness, psychotic behavior, confusion, coma, and potentially death.
What is the key difference between obstructive and restrictive lung diseases?
Obstructive diseases: Difficulty exhaling due to airway collapse.
Restrictive diseases: Difficulty inhaling due to lung stiffness or reduced expansion.
Name two obstructive and two restrictive lung diseases.
Obstructive: Asthma, Emphysema
Restrictive: Pulmonary Fibrosis, Obesity-related hypoventilation
How does lung volume change in obstructive vs. restrictive diseases?
Obstructive → Increased total lung capacity (TLC) and residual volume (RV) due to trapped air.
Restrictive → Decreased TLC and RV because the lungs can’t expand properly.
How do FVC and FEV₁ change in obstructive vs. restrictive diseases?
Obstructive → FEV₁ is significantly reduced, but FVC is relatively normal. (Low FEV₁/FVC ratio)
Restrictive → Both FEV₁ and FVC decrease, but the ratio remains normal.
In which type of disease (obstructive or restrictive) does the FEV₁/FVC ratio remain normal?
Restrictive diseases, because both FEV₁ and FVC decrease proportionally.
What are the main causes and symptoms of emphysema?
Cause: Smoking, pollutants, genetic factors
Symptoms:
Destruction of alveoli → Less surface area for gas exchange
High lung compliance (lungs too stretchy)
Pulmonary hypertension
What distinguishes chronic bronchitis from emphysema?
Chronic bronchitis → Excess mucus production, leading to persistent cough.
Emphysema → Alveolar destruction, leading to reduced gas exchange.
What happens to airway resistance in asthma?
It increases due to bronchoconstriction (narrowing of airways), making it harder to exhale.
What is the primary cause of pulmonary edema?
Increased pulmonary capillary pressure forces fluid into lung tissues, often due to left heart failure.
What are two key symptoms of pulmonary edema?
Pink, frothy sputum
Shortness of breath (dyspnea)
Does oxygen therapy help with anemia? Why or why not?
Only partially—it increases oxygen levels in the blood, but the real issue is the lack of hemoglobin to carry it.
Why doesn’t oxygen therapy work in cyanide poisoning?
Cyanide blocks cellular oxygen usage, so even if blood oxygen levels are high, cells can’t use it for energy production.
What is atelectasis, and how does it differ from pneumothorax?
Atelectasis: Lung collapse due to internal airway obstruction (like mucus or lack of surfactant).
Pneumothorax: Lung collapse due to air entering the pleural space.
