Newton’s laws of Motion Wave properties of light Ionizing Radiation Wave properties of light Nerve Conduction Direct Current (DC) Fluids Work, Energy and Power PHYS 101 CH: 3 FLUIDS Instructor: Sujood Alazzam 2016/2017

CHAPTER OUTLINE 13.1 Archimedes' Principle. Fluids CH:3 13.2 The Equation of continuity, Stream line flow. 13.3 Bernoulli’s equation 13.4 Static consequences of Bernoulli’s equation. 13.5 Role of gravity in blood circulation 13.6 Blood Pressure Measurements Using the Sphygmomanometer 14.1 Viscosity

Lecture 9: 13.5 Role of gravity in blood circulation Fluids CH:3 Lecture 9: 13.5 Role of gravity in blood circulation

OBJECTIVES We will be able to: Fluids CH:3 We will be able to: Describe measuring gas pressures using manometers Describe the system of blood flow through the body Describe the role of gravity in the circulation.

The Manometer equal p Manometer = The open-tube manometer is a U-shaped tube used for measuring gas pressures.

It contains a liquid that may be mercury or, for measurements of low pressures, water or oil.

The manometer can also be used to measure pressures in a liquid, provided that the liquid does not mix with the manometer fluid. One end of the tube is open to the atmosphere, and the other end is in contact with the gas in which the pressure is to be measured.

The pressure PFluid in this equation is the absolute pressure. The difference between this and atmospheric pressure, Pfluid - Patm , is the gauge pressure. The gauge pressure is then exactly equal to ( g ρHg h)

13.5 The Role Of Gravity In The Circulation Humans have adapted to the problems of moving blood upward a large distance against the force of gravity. The venous system used to return blood from the lower extremities to the heart.

Animals that have not, such as snakes, eels, and even rabbits, will die if held head upwards; the blood remains in the lower extremities, and the heart receives no blood from the venous system.

In the reclining position, the pressures everywhere are almost the same. The small pressure drop between the heart and the feet or brain is due to the viscous forces. However, the pressures at the three points are quite different in the standing person, reflecting the large difference in their heights.

where ρ is the density of blood. we can use Bernoulli's equation, P + ρ g h + 𝟏 𝟐 ρ 𝒗 𝟐 = constant, The velocities in the three arteries are small and roughly equal PF = PH + ρ g hH = PB + ρ g hB where ρ is the density of blood.

This explains why the pressures in the lower and upper parts of the body are very different when the person is standing, although they are about equal when reclining. Picture Page Layout Here is a place holder for the text. The coins on this page can be removed. You may delete this text.

Two Picture Page Layout This situation poses several problems. The most important are the tendency for blood to drain out of the venous side of the upper body back to the heart and the difficulty of lifting blood from the lower extremities up to the heart.

The muscles surrounding the veins contract and cause constriction. In the lower extremities, the problem is to pump the blood "uphill.“ because the veins have a capacity for passive expansion and blood storage than do arteries The veins in the extremities contain valves that open when blood flows toward the heart and close if the blood moves away from the heart. Blood is returned to the heart, at least partially, by the pumping action associated with breathing and by the flexing of skeletal muscle, as in walking. These muscle contractions squeeze the veins, and the valves ensure that the resultant blood flow is toward the heart. To retard drainage from the venous side of the upper body,

The importance of this is illustrated by the fact that a soldier who is required to stand at strict attention may faint because of insufficient venous return. Once horizontal, the pressures are equalized, and the soldier regains consciousness.

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