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Standing a long time can lead to an accumulation of blood in the legs and swelling. This is the reason why soldiers who are required to stand still for long periods of time have been known to faint. Elastic bandages around the calf can help prevent this accumulation and can also help provide increased pressure to enable the veins to send blood back up to the heart. For similar reasons, doctors recommend tight stockings for long-haul flights.

Blood pressure may also be measured in the major veins, the heart chambers, arteries to the brain, and the lungs. But these pressures are usually only monitored during surgery or for patients in intensive care since the measurements are invasive. To obtain these pressure measurements, qualified health care workers thread thin tubes, called catheters, into appropriate locations to transmit pressures to external measuring devices.

The heart consists of two pumps—the right side forcing blood through the lungs and the left causing blood to flow through the rest of the body ( [link] ). Right-heart failure, for example, results in a rise in the pressure in the vena cavae and a drop in pressure in the arteries to the lungs. Left-heart failure results in a rise in the pressure entering the left side of the heart and a drop in aortal pressure. Implications of these and other pressures on flow in the circulatory system will be discussed in more detail in Fluid Dynamics and Its Biological and Medical Applications .

Two pumps of the heart

The heart consists of two pumps—the right side forcing blood through the lungs and the left causing blood to flow through the rest of the body.

The figure shows the circulatory system in the human body. The figure shows the right atrium and the left atrium, right ventricle and the left ventricle of the heart. The heart consists of two pumps—the right side forcing blood through the lungs and the left causing blood to flow through the rest of the body.
Schematic of the circulatory system showing typical pressures. The two pumps in the heart increase pressure and that pressure is reduced as the blood flows through the body. Long-term deviations from these pressures have medical implications discussed in some detail in the Fluid Dynamics and Its Biological and Medical Applications . Only aortal or arterial blood pressure can be measured noninvasively.

Pressure in the eye

The shape of the eye is maintained by fluid pressure, called intraocular pressure    , which is normally in the range of 12.0 to 24.0 mm Hg. When the circulation of fluid in the eye is blocked, it can lead to a buildup in pressure, a condition called glaucoma    . The net pressure can become as great as 85.0 mm Hg, an abnormally large pressure that can permanently damage the optic nerve. To get an idea of the force involved, suppose the back of the eye has an area of 6 . 0 cm 2 size 12{6 "." 0`"cm" rSup { size 8{2} } } {} , and the net pressure is 85.0 mm Hg. Force is given by F = PA size 12{F= ital "PA"} {} . To get F size 12{F} {} in newtons, we convert the area to m 2 ( 1 m 2 = 10 4 cm 2 ). Then we calculate as follows:

F = gA = 85 . 0 × 10 3 m 13 . 6 × 10 3 kg/m 3 9 . 80 m/s 2 6 . 0 × 10 4 m 2 = 6.8 N.

Eye pressure

The shape of the eye is maintained by fluid pressure, called intraocular pressure. When the circulation of fluid in the eye is blocked, it can lead to a buildup in pressure, a condition called glaucoma. The force is calculated as

F = gA = 85 . 0 × 10 3 m 13 . 6 × 10 3 kg/m 3 9 . 80 m/s 2 6.0 × 10 4 m 2 = 6.8 N.

Questions & Answers

A body travelling at a velocity of 30ms^-1 in a straight line is brought to rest by application of brakes. if it covers a distance of 100m during this period, find the retardation.
Pamilerin Reply
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Grace Reply
what's acceleration
Joshua Reply
The change in position of an object with respect to time
Mfizi
Acceleration is velocity all over time
Pamilerin
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Stephen
It's not It's the change of velocity relative to time
Laura
Velocity is the change of position relative to time
Laura
acceleration it is the rate of change in velocity with time
Stephen
acceleration is change in velocity per rate of time
Noara
what is ohm's law
Stephen
Ohm's law is related to resistance by which volatge is the multiplication of current and resistance ( U=RI)
Laura
how i don understand
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how do I access the Multiple Choice Questions? the button never works and the essay one doesn't either
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How do you determine the magnitude of force
Peace Reply
mass × acceleration OR Work done ÷ distance
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Which eye defect is corrected by a lens having different curvatures in two perpendicular directions?
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acute astigmatism?
the difference between virtual work and virtual displacement
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How do you calculate uncertainties
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What is Elasticity
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using a micro-screw gauge,the thickness of a piece of a A4 white paper is measured to be 0.5+or-0.05 mm. If the length of the A4 paper is 26+or-0.2 cm, determine the volume of the A4 paper in: a). Cubic centimeters b). Cubic meters
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what is module
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why it is possible for an object(man) to stay on air without falling down?
akande Reply
its impossible, what do you mean exactly?
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Exactly
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it's impossible
Your
Why is it not possible to stand in air?
bikko
the air molecules are very light enough to oppose the gravitational pull of the earth on the man..... hence, freefall occurs
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because of gravitational forces
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this mostly occur in space
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what is physics
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no life without physics ....that should tell you something
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E=MC^2
study of matter and energy and an inter-relation between them.
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that's how the mass and energy are related in stationery frame
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Kinetic energy is the energy due to montion of waves,electrons,atoms, molecule,substances an object s.
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meteor are the glowy (i.e. heated when the enter into our atmosphere) parts of meteoroids. now, meteoroids are the debris resulting from the collision of asteroids or comets. yes, it occurs in daytime too, but due to the daylight, we cant observe it as clearly as in night
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wich method we use to find the potential on a grounded sphere
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Physics is the science that studies everything around us from the smallest things like quarks to the biggest things like galaxies. It's simply everything.
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It talks mainly about matter with related topics such as forces energy gravity and time. It's amazing
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Physics generally is the study of everything around us.
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physics is the branch of sceince
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physics is the branch of sceince that deal with motion
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physics is the branch of sceince that deal with motion &energy
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Energy, it always remains there in a physical system. it can only take the form either in motion (kinetic energy) or in rest (potential energy)
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In nature organisms feed on one another in an orderly way.
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Practice Key Terms 5

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Source:  OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
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