/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 76 II A patient has developed an an... [FREE SOLUTION] | 91Ó°ÊÓ

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II A patient has developed an aneurysm in the aorta, a short section where the diameter is twice the normal diameter. In the aneurysm, the speed of the blood is____ than in the section before the aneurysm, and the pressure is _______ than in the section before the aneurysm. A. Greater, greater B. Greater, less C. Less, greater D. Less, less

Short Answer

Expert verified
The speed of blood in the aneurysm is less and the pressure is greater. So, the correct option is 'C. Less, greater'.

Step by step solution

01

Identify Knowns and Relationships

From the problem brief, the aneurysm has twice the normal diameter, meaning it has a larger cross-sectional area than the normal section. Since the blood is the 'fluid' in this case, the principle of fluid continuity can be applied.
02

Apply Continuity Principle

According to the continuity principle, the speed of fluid decreases when the cross-sectional area increases. This occurs in order to conserve the total volume flow rate. So, in the aneurysm, the speed of blood will be less than in the section before the aneurysm.
03

Apply Bernoulli's Principle

Next, Bernoulli's equation will be used to deduce the pressure changes. Bernoulli's equation says that the sum of kinetic energy, potential energy, and fluid pressure per unit volume remains constant. If the speed of blood reduces in the aneurysm, kinetic energy per unit volume decreases. To keep Bernoulli's sum constant, it implies that pressure per unit volume will have to increase. So, in the aneurysm, the pressure of blood will be greater than in the section before the aneurysm.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Continuity Principle
Consider a river flowing smoothly; as it reaches a wider section, it appears to slow down, while in narrower parts, it speeds up. This phenomenon is guided by the continuity principle, an essential concept in fluid dynamics. It states that for any incompressible and steady flow of fluid, the product of the cross-sectional area and the fluid velocity at any point is constant throughout the conduit. In simpler terms, as the area of the pipe or vessel increases, the fluid speed must decrease to keep the flow rate consistent, and conversely, as the area decreases, the speed must increase.
Imagine a balloon with an opening, upon squeezing one part of the balloon, the air or water inside speeds up to exit the narrower opening. Similarly, in the aneurysm problem, the widened diameter results in a reduction of blood speed to maintain the continuity of flow. It's essential to understand that the volume of blood that enters the aneurysm per unit time is equal to the volume that exits it, ensuring the preservation of mass within the system.
Bernoulli's Equation
Now let's dive into Wolfgang Amadeus movement level suspense, generated by Bernoulli's equation, a statement of energy conservation for fluid motion. It relates several forms of kinetic and potential energy in a flowing fluid. Mathematically, Bernoulli's equation is expressed as \( P + \frac{1}{2} \rho v^2 + \rho gh = \text{constant} \),where \( P \) is the fluid pressure, \( \rho \) is the fluid density, \( v \) represents the fluid's velocity, \( g \) is the acceleration due to gravity, and \( h \) is the height above the reference point.
In the context of the aneurysm scenario, when the blood flows into the wider section, its velocity decreases. According to Bernoulli's equation, if the flow speed decreases within a streamline (the path the blood takes), the pressure must increase if the height remains constant and losses are negligible. This balance is crucial for understanding how the energy is conserved as the blood travels through different diameters within the vasculature.
Kinetic Energy
When you think about energy, envision a sprinter bursting forward with great speed—this is kinetic energy in motion, energy which an object possesses due to its movement. In fluid dynamics, the kinetic energy per unit volume of flowing fluid is given by the expression \( \frac{1}{2} \rho v^2 \).
As the velocity \( v \) of the blood drops within the aneurysm, so does its kinetic energy. The conservation of energy dictates that this energy must be converted to other forms or transferred to different parts of the fluid. In the case of our example, when the blood’s velocity lessens in the aneurysm, the kinetic energy is partially converted into pressure energy, leading to an increase in blood pressure inside the aneurysm. This transformation is a beautiful dance between different forms of energy, each changing and compensating to maintain the overall energy balance.
Pressure Changes
Pressure can be thought of as an invisible force distributed over an area. In fluids, pressure changes are at the heart of how they behave under various conditions. It's the hallmark of interactions between fluid particles and their surroundings. Remember the sensation of diving deep into a pool and feeling the water pressure build up around your ears? That's the increase in fluid pressure with depth.
In the arterial aneurysm example, the widened section triggers a decrease in blood speed, and by Bernoulli's principle, an increase in pressure. This pressure change is fundamental to the understanding of how blood flow and pressure are related in our bodies and how they adapt to the shapes and constraints of our blood vessels. Pressure is the silent, unseen force that pushes the blood through our veins and arteries, reaching every cell with life-sustaining oxygen and nutrients while adjusting to the unique architecture of our vascular system.

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Most popular questions from this chapter

Water flowing through a 2.0 -cm-diameter pipe can fill a 300 L bathtub in \(5.0 \mathrm{min} .\) What is the speed of the water in the pipe?

A diver \(50 \mathrm{m}\) deep in \(10^{\circ} \mathrm{C}\) fresh water exhales a \(1.0-\mathrm{cm}-\) diameter bubble. What is the bubble's diameter just as it reaches the surface of the lake, where the water temperature is \(20^{\circ} \mathrm{C} ?\) Hint: Assume that the air bubble is always in thermal equilibrium with the surrounding water.

Sustained exercise can increase the blood flow rate of the heart by a factor of 5 with only a modest increase in blood pressure. This is a large change in flow. Although several factors come into play, which of the following physiological changes would most plausibly account for such a large increase in flow with a small change in pressure? A. A decrease in the viscosity of the blood B. Dilation of the smaller blood vessels to larger diameters C. Dilation of the aorta to larger diameter D. An increase in the oxygen carried by the blood

The nicotine in tobacco causes the arteries to constrict. A rapid constriction of the arteries likely leads to A. A rapid decrease in blood pressure. B. No change in blood pressure. C. A rapid increase in blood pressure.

As blood goes from the left ventricle through the arteries and veins of the human body, both its speed and pressure change. The arteries and arterioles can either constrict, reducing the area, or dilate, increasing the area, in response to certain conditions. Both of these changes can affect blood flow and blood pressure. An artery can also develop a permanent narrow area (stenosis) or a permanent wide area (aneurysm). Both of these changes can have significant health consequences. Suppose that in response to some stimulus a small blood vessel narrows to \(90 \%\) of its original diameter. If there is no change in the pressure across the vessel, what is the ratio of the new volume flow rate to the original flow rate? A. 0.66 B. 0.73 C. 0.81 D. 0.90

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