Calculating Pressure Drop in a Bronchial Constriction

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SUMMARY

The discussion focuses on calculating the pressure drop in a bronchial constriction during inhalation, where air moves at 15 cm/s and doubles in speed through the constriction. Participants clarify that, contrary to common assumptions about pressure in narrowed passages, the pressure at the constriction is lower than at the inlet due to the principles outlined in the Bernoulli equation. This pressure difference is essential for driving airflow from the inlet to the constriction, highlighting the importance of understanding fluid dynamics in biological systems.

PREREQUISITES
  • Understanding of fluid dynamics principles, specifically the Bernoulli equation.
  • Knowledge of airflow mechanics in biological systems.
  • Familiarity with concepts of incompressible flow.
  • Basic mathematical skills for calculating pressure and flow rates.
NEXT STEPS
  • Study the Bernoulli equation in detail to understand its applications in fluid dynamics.
  • Explore the effects of constriction on airflow in respiratory physiology.
  • Learn about the implications of pressure drop in various medical conditions, such as asthma.
  • Investigate computational fluid dynamics (CFD) simulations for modeling airflow in bronchial passages.
USEFUL FOR

Medical professionals, respiratory therapists, and students in biomedical engineering or physiology who are interested in the mechanics of airflow and pressure dynamics in the respiratory system.

frenchy7322
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Q: When a person inhales, air moves down the bronchus (windpipe) at 15 cm/s. The average flow speed doubles through a constriction in the bronchus. Assuming incrompressible flow, determine the pressure drop in the constriction.

OK what confuses me is that I thought that if you decrease the width of a passage (e.g cholesterol in an artery) you increase pressure. However this asks for pressure DROP in constriction?:confused:

Equation I thought would be P = F/A, but not real sure at all.

Please help me get the ball rolling!
 
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To help you judge, let's compare this.
When there is a constriction in a pipe, the overall pressure in the WHOLE tube should be higher than that of a pipe with no constriction, given similar inlet flow speed. Now look at the tube with constriction, and compare the pressure at the inlet and at the constriction, the pressure at the constriction is always lower. It is this pressure difference that drives the air from inlet to the constriction! That phenomena is governed by the Bernoulli equation.
 

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