Why doesn't our body experience equal pressure when we press our finger?

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SUMMARY

The discussion centers on the application of Pascal's Law to the human body, questioning why equal pressure is not experienced throughout when pressing a finger. It concludes that the human body does not behave as a perfect fluid due to various factors, including the presence of solid structures like bones and organs, the air in the lungs following Boyle's Law, and the complex interactions of pressure differentials created by the heart and arteries. The body is more accurately modeled as a complex structure rather than a simple fluid-filled bag.

PREREQUISITES
  • Understanding of Pascal's Law and its implications in fluid mechanics.
  • Basic knowledge of Boyle's Law and its application to gases.
  • Familiarity with human anatomy, particularly the circulatory and muscular systems.
  • Concepts of pressure differentials in biological systems.
NEXT STEPS
  • Research the implications of Pascal's Law in real-world applications beyond ideal fluids.
  • Study the mechanics of human anatomy, focusing on the circulatory system and its pressure dynamics.
  • Explore the differences between solid and fluid mechanics in biological contexts.
  • Investigate how pressure differentials affect bodily functions, particularly in the lungs and kidneys.
USEFUL FOR

Students of physics, medical professionals, and anyone interested in the biomechanics of the human body will benefit from this discussion, particularly those exploring the complexities of fluid dynamics in biological systems.

aditya ver.2.0
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According to Pascal Law, when there is an increase in pressure at any point in a confined fluid, there is an equal increase at every other point in the container. Then why doesn't our entire body experiences the same pressure throughout the body when we press our finger. Isn't the entire body filled with fluid, i.e. blood and water?
 
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aditya ver.2.0 said:
According to Pascal Law, when there is an increase in pressure at any point in a confined fluid, there is an equal increase at every other point in the container. Then why doesn't our entire body experiences the same pressure throughout the body when we press our finger. Isn't the entire body filled with fluid, i.e. blood and water?

Our bodies don't behave as perfect fluids. They're covered with skin that stretches differently in different directions, the lungs are full of air which obeys Boyle's law instead of Pascal's, the heart and arteries are working hard at creating pressure differentials throughout the circulatory system, membranes in the kidneys and digestive track do interesting things with osmotic pressures, bones, tendons, and connective tissues are fairly solid...

Modeling the human body as a bag filled with liquid isn't very accurate across a wide range of conditions, including (not coincidentally) those which we most often encounter in daily life.
 
But sir, still our body has a large portion of fluid ranging from blood to hormones. So what the problems?
 
The problem is, the human body is still not a bag of skin with a bunch of fluid inside. When you move your body, you don't slosh inside, like when you carry a pail half-filled with water. Your bones, organs, muscles, etc. behave closer to solid materials than they do liquids.
 
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aditya ver.2.0 said:
But sir, still our body has a large portion of fluid ranging from blood to hormones. So what the problems?

You could model the body as a sausage shaped balloon, full of water (it would need to be contained in some sort of basket or it would form a tear drop shape ). In that model, if you squeezed the top, the pressure at the bottom would also increase.

It is usually very problematical to try to apply simple basic ideas in Physics to complicated biological structures. There are too many variables involved for an accurate answer to be obtained.
 

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