barometric pressure and conditions Flashcards
What triggers hyperventilation at high altitude?
Low PaO₂ (arterial oxygen) detected by peripheral chemoreceptors (carotid bodies).
What is the initial effect of hyperventilation on CO₂ levels?
CO₂ clearance increases, leading to respiratory alkalosis (high pH).
What happens to blood pH during respiratory alkalosis?
pH increases due to CO₂ loss, which reduces ventilation temporarily.
how does the body prevent alkalosis
kidneys excrete bicarbonate (HCO₃⁻), allowing more acid to stay in the blood, restoring pH andventilation increases again
what is polycythaemia
a condition characterized by an increased red blood cell (RBC) count in the blood, leading to higher hemoglobin levels.
what is the location of arterial baroreceptors
- Caroid sinuses
- Aortic arch
what is the function of arterial baroreceptors
Arterial baroreceptors help regulate blood pressure (BP) via the Baroreceptor Reflex by sensing changes in arterial wall stretch caused by fluctuations in blood pressure.
what do arterial baroreceptors do when blood pressure increases (hypertension)
- Increased arterial stretch → Increased baroreceptor firing.
- Sends signals to the medulla
- Activates parasympathetic nervous system (PNS):
✅ Decreases heart rate
✅ Dilates blood vessels → Lowers BP.
what do arterial baroreceptors do when blood pressure decreases (hypotension)
- Decreased arterial stretch → Reduced baroreceptor firing.
- Less inhibition of the sympathetic nervous system (SNS).
- Activates sympathetic response:
✅ Increases heart rate
✅ Constricts blood vessels → Raises BP.
what is nitrogen narcosis
Nitrogen Narcosis is a reversible, altered mental state caused by breathing high partial pressures of nitrogen (N₂) at depth during scuba diving.
As a diver descends, the ambient pressure increases, causing more nitrogen to dissolve into the bloodstream and tissues.
Nitrogen acts as a neurological depressant, affecting the central nervous system (CNS) similarly to alcohol or anesthetics.
what are the consequences of Nitrogen narcosis
50m (150 ft)
* “Cocktail” effect (euphoria and drowsiness)
50-90m (150 - 300 ft)
* Fatigued and weak
* Loss of coordination
* Clumsiness
100-120m (350 - 400 ft)
* Lose consciousness
how to prevent nitrogen narcosis
Limit Depth → Stay above 30m
Use N2 free gas
Ascend Immediately → Narcosis symptoms disappear quickly upon rising to shallower depths.
what is decompression sickness
occurs when dissolved gases (mainly nitrogen) form bubbles in the blood and tissues due to a rapid decrease in pressure after diving, high-altitude flying, or spacewalks.
Gas embolus in circulation → tissue ischaemia
Bubble formation in the myelin shea
what are the consequences of decompression sickness
Joint and muscle pain
Numbness, weakness, paralysis
fatigue
Confusion, dizziness, loss of consciousness
Chest pain, difficulty breathing (“the chokes”)
how to prevent decompression sickness
slow descent
N2 gas replacement (Helium)
Exhale during ascent
Stay Hydrated → Reduces nitrogen retention in tissues.
Avoid Alcohol & Heavy Exercise Before/After Dives
wait before flying
what is ‘pneumothorax’
a condition where air enters the pleural cavity, the space between the lung and chest wall. This disrupts the normal negative pressure that keeps the lungs inflated, leading to partial or complete lung collapse.
what are the Consequences of Pneumothorax on Respiratory Function
✅ Lung Collapse (Atelectasis)
✅ Decreased Oxygenation (Hypoxemia): Less oxygen reaches the blood due to impaired ventilation.
✅ Dyspnea (Shortness of Breath): due to reduced lung capacity.
✅ Chest Pain & Decreased Breath Sounds: Air in the pleural cavity disrupts normal lung sounds.
✅ Tension Pneumothorax (Severe Cases): Can cause mediastinal shift, compressing the heart & major vessels → low blood pressure, shock, & death if untreated.
