Biology Respiration / Gaseous Exchange MDCAT 2017
PMDC Verified Question 27 of 34
Label the prominent dome-shaped muscular boundary located at the base of the lungs separating the thoracic and abdominal cavities:
A
Pleura
B
Chest cavity
C
Inter-coastal muscle
D
Diaphragm
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Diaphragm
Concept: The mechanism of breathing relies heavily on muscular boundaries that alter the volume of the thoracic cavity.

Solution:
  • In standard anatomical diagrams of the human respiratory system, the prominent dome-shaped structure at the very base of the lungs is the diaphragm.
  • It is a thin sheet of skeletal muscle that completely separates the thoracic (chest) cavity from the abdominal cavity.


Why other options are incorrect:
  • Pleura: The double membrane enclosing the lungs, not a muscular boundary at the base.
  • Inter-coastal muscle: Muscles located between the ribs.
  • Chest cavity: The entire space, not a specific muscular structure.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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