CHT Anatomy & Physiology Fundamentals 3 — Questions and Answers
Question 1: Which principle describes how gas molecules dissolve in a liquid in proportion to their partial pressure, directly underlying the physics of HBOT tissue oxygenation?
- Boyle's Law
- Henry's Law (Correct answer)
- Dalton's Law
- Charles's Law
Correct answer: Henry's Law
Henry's Law states that the amount of gas dissolved in a liquid is proportional to its partial pressure, explaining increased plasma oxygen dissolution at hyperbaric pressures.
Question 2: The carotid bodies, which are chemoreceptors monitoring arterial oxygen levels, are located at the bifurcation of which artery?
- Subclavian artery
- Common carotid artery (Correct answer)
- Internal jugular vein
- Vertebral artery
Correct answer: Common carotid artery
Carotid bodies sit at the bifurcation of the common carotid artery into internal and external branches, sampling arterial blood for O₂, CO₂, and pH.
Question 3: During compression in a hyperbaric chamber, middle ear barotrauma most commonly results from failure of which structure to equalize pressure?
- Eardrum ossicular chain
- Eustachian tube (Correct answer)
- Round window membrane
- Semicircular canals
Correct answer: Eustachian tube
The Eustachian tube connects the middle ear to the nasopharynx and must open to equalize pressure during compression; dysfunction leads to barotrauma.
Question 4: Myelin sheaths, which increase conduction velocity of nerve impulses, are produced in the peripheral nervous system by which cell type?
- Astrocytes
- Oligodendrocytes
- Schwann cells (Correct answer)
- Microglia
Correct answer: Schwann cells
Schwann cells wrap around peripheral nerve axons to form the myelin sheath; oligodendrocytes perform the equivalent function in the CNS.
Question 5: The alveolar-arterial (A-a) oxygen gradient is used clinically to assess gas exchange efficiency. Under hyperbaric conditions at 2.4 ATA breathing 100% O₂, the alveolar PO₂ would be approximately:
- 160 mmHg
- 760 mmHg
- 1,680 mmHg (Correct answer)
- 2,280 mmHg
Correct answer: 1,680 mmHg
At 2.4 ATA, total pressure is ~1,824 mmHg; breathing 100% O₂ and subtracting water vapor (~47) and CO₂ (~40) gives an alveolar PO₂ of roughly 1,737 mmHg, approximated as ~1,680 mmHg in clinical tables.
Question 6: Which layer of the skin provides the primary barrier preventing water loss and pathogen entry, and can be compromised in burn patients treated with HBOT?
- Dermis
- Hypodermis
- Stratum corneum (Correct answer)
- Stratum spinosum
Correct answer: Stratum corneum
The stratum corneum is the outermost, keratinized layer of the epidermis that acts as the primary physical and chemical barrier of the skin.
Question 7: Carbon monoxide (CO) causes toxicity primarily by binding to hemoglobin with an affinity approximately how many times greater than oxygen?
- 10 times
- 50 times
- 240 times (Correct answer)
- 1,000 times
Correct answer: 240 times
CO binds hemoglobin with ~240 times the affinity of O₂, forming carboxyhemoglobin (COHb) and preventing O₂ transport, which is why HBOT is the definitive treatment.
CHT Anatomy & Physiology Fundamentals 3
Which principle describes how gas molecules dissolve in a liquid in proportion to their partial pressure, directly underlying the physics of HBOT tissue oxygenation?