Related Experiment Video
Updated: Jun 28, 2025
07:30
In Vitro Model of Physiological and Pathological Blood Flow with Application to Investigations of Vascular Cell Remodeling
Published on: November 3, 2015
9.6K
Considerations on static pressure gradients in closed circulatory systems
Nato Popara1, Denis Cvitković2, Marinko Vilić3
1Deparment of Physics, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatia.
Physiological Reports
|April 11, 2024
Summary
The siphon principle in mammalian blood circulation is debated. Our study shows the static pressure gradient equals the hydrostatic gradient, negating the need for complex mechanisms like baffles.
Area of Science:
- Physiology
- Fluid Dynamics
- Biophysics
Background:
- The siphon principle is proposed to explain blood circulation in mammals.
- This principle suggests no extra work is needed to pump blood above the heart and no gravitational static pressure gradient exists.
Purpose of the Study:
- To analyze the validity of the siphon principle in mammalian circulatory systems.
- To determine the implications of the siphon principle on blood flow dynamics and pressure gradients.
Main Methods:
- Mathematical modeling of blood circulation using a siphon principle.
- Analysis of static pressure gradients in a simplified circulatory model, ignoring hydraulic resistance.
- Extension of the proof to other models, including vascular waterfalls.
Main Results:
- The static pressure gradient in a siphon model of blood circulation is equal to the hydrostatic gradient.
- The geometry of the circulatory system does not affect this relationship.
- The controversy over the siphon principle has no impact on the description of blood circulation.
Conclusions:
- Mechanisms like the "baffle" are unnecessary to explain pressure gradients in blood circulation.
- The study's findings are supported by empirical data and everyday observations.
- A simplified physical model accurately describes pressure dynamics in circulatory systems.
Related Concept Videos
01:24Static, Stagnation, Dynamic and Total Pressure
359
The concept of static, stagnation, dynamic, and total pressure is fundamental in fluid dynamics, often explained using Bernoulli's equation:
359
01:14Pressure of Fluids
15.9K
There are many examples of pressure in fluids in everyday life, such as in relation to blood (high or low blood pressure) and in relation to weather (high- and low-pressure weather systems). A given force can have a significantly different effect, depending on the area over which the force is exerted. For instance, a force applied to an area of 1 mm2 has a pressure that is 100 times greater than the same force applied to an area of 1 cm2. That's why a sharp needle is able to poke through...
15.9K
01:04Pascal's Law
8.5K
In 1653, the French philosopher and scientist Blaise Pascal published "Treatise on the Equilibrium of Liquids," which discussed the principles of static fluids. A static fluid is a fluid that is not in motion. When a fluid is not flowing, we say that the fluid is in static equilibrium. If the fluid is water, we say it is in hydrostatic equilibrium. For a fluid in static equilibrium, the net force on any part of the fluid must be zero; otherwise, the fluid will start to flow. Pascal...
8.5K
01:01Bernoulli's Principle
9.7K
Bernoulli's equation incorporates how fluid pressure changes across a static, incompressible fluid by equating the kinetic energy contribution to zero. It is also helpful in analyzing horizontal flows in which the gravitational energy density is constant throughout. The latter equation is so useful that it is called Bernoulli's principle. According to Bernoulli's principle, the fluid pressure drops if the speed increases and vice versa.
Bernoulli's principle has several...
Bernoulli's principle has several...
9.7K
01:11Pressure Variation in a Fluid at Rest
250
In a fluid at rest, the pressure at any point beneath the fluid surface depends solely on the depth, not on the container's shape or size. This principle, known as hydrostatic pressure, arises because, in stationary fluids, there is no acceleration, meaning the forces within the fluid balance out. Only vertical forces, caused by the weight of the fluid above, contribute to pressure changes with depth.
When measuring pressure at two different levels within the fluid, the difference in...
When measuring pressure at two different levels within the fluid, the difference in...
250
01:16Bernoulli's Equation for Flow Normal to a Streamline
855
Bernoulli's equation for flow normal to a streamline explains how pressure varies across curved streamlines due to the outward centrifugal forces induced by the fluid's curvature. The pressure is higher on the inner side of the curve, near the center of curvature, and decreases outward to balance these centrifugal forces.
The pressure difference depends on the fluid's velocity and radius of curvature. The pressure variation is minimal in flows with nearly straight streamlines.
The pressure difference depends on the fluid's velocity and radius of curvature. The pressure variation is minimal in flows with nearly straight streamlines.
855