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The pressure (

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Effects of atmospheric pressure on human

• It has now been proved in medical science of
  aviation and space that excessive heights above
  the Earths surface cause physiological changes
  in the human body that are manifested by a
  feeling of closeness and constriction in the
  breast until one reaches the critical stage .
• This is because the higher one goes up into the
  sky, the lesser atmospheric pressure and the
  lesser oxygen is there.

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• If man goes up to a height of 10,000 feet above
  sea level, he feels decrease of both oxygen and
  atmospheric pressure. If he goes higher up to
  16,000 feet high, his pulse increases and so do
  his breathing and blood pressure, in order to
  provide his body with the necessary oxygen. If,
  however, he goes up higher to 25,000 feet high,
  his body fails to cope with such an unfamiliar
  height. So what happens? Certain symptoms begin
  to show. First, he feels that his breast is
  closed and constricted
• If, however, man goes up more than 25,000 feet
  high, he loses consciousness. That is why planes
  that fly higher than 40,000 feet high are
  provided with eight times as much air as they are
  on the Earths surface, so as to make the
  pressure in them equal that on the Earths
  surface otherwise passengers would lose
  consciousness.

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• Atmospheric Pressure is produced by the weight of
  the gases in the atmosphere, acts on every body
  and in all directions. Its effects are therefore
  neutralized. At sea level, it equals 14.7 psi or
  1.03 kg/cm2 larger values are often expressed in
  atmospheres. Atmospheric pressure decreases with
  the increase of height.
• Weather has a profound effect on human health
  and well-being. It has been demonstrated that
  weather is associated with changes in birth
  rates, and sperm counts, with outbreaks of
  pneumonia, influenza and bronchitis, and is
  related to other morbi dity effects linked to
  pollen concentrations and high pollution levels.

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atmospheric pressure

• Air pressure is the force exerted on you by the
  weight of tiny particles of air (air molecules).
  Although air molecules are invisible, they still
  have weight and take up space. Since there's a
  lot of "empty" space between air molecules, air
  can be compressed to fit in a smaller volume.

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• Atmospheric pressure is sometimes defined as the
  force per unit area exerted against a surface by
  the weight of air above that surface at any given
  point in the Earth's atmosphere. In most
  circumstances atmospheric pressure is closely
  approximated by the hydrostatic pressure caused
  by the weight of air above the measurement point.
  Low pressure areas have less atmospheric mass
  above their location, whereas high pressure areas
  have more atmospheric mass above their location.
  Similarly, as elevation increases there is less
  overlying atmospheric mass, so that pressure
  decreases with increasing elevation. A column of
  air one square inch in cross-section, measured
  from sea level to the top of the atmosphere,
  would weigh approximately 65.5 newtons
  (14.7 lbf). The weight of a 1 m2 (11 sq ft)
  column of air would be about 101 kN (10.3 tf).

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Experiments on atmospheric pressure

• No Sucker Fill a small jar with water. Poke a
  hole in the lid big enough for a straw. Put a
  straw into the water through the hole in the lid
  and seal up the space around the straw with
  plasticine. Now try to suck water through the
  straw. Be sure there are no leaks. What happens?
  (Or doesn't happen?)

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Why couldn't I get any water from the jar?

• When you drink from an open glass of water, air
  pressure allows the water to travel up the straw.
  When you reduce the pressure inside your mouth
  (by sucking on the straw), the surrounding air
  pressure pushes down on the water and forces the
  liquid up the straw. But when air pressure on the
  water is blocked (when you seal the jar lid),
  there is no air pressure to help push the water
  up your straw. The air can't get to the water to
  push on it, so it doesn't go up the straw.
  Regardless of how hard you suck, the water stays
  where it is!

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• Experiment 2
• When a balloon is blown up, the air pressure
  inside the balloon slowly becomes greater than
  the air pressure outside the balloon. Since the
  balloon is made of rubber and is expandable, it
  grows larger and larger. When the balloon is
  popped, the air escapes instantly. The sound you
  hear is from the molecules of air inside the
  balloon coming into sudden contact with the
  molecules of air outside the balloon.

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• Experiment 3
• The milk jug will crumple in on itself. When you
  added the hot water, it caused the air
  temperature inside the jug to rise. While the
  container was sealed no air could get into or out
  of the jug. When the water inside the jug cooled,
  the air cooled and caused the pressure inside the
  jug to decrease. As the pressure on the inside
  walls of the jug decreased, the walls of the jug
  collapsed. Since there wasn't enough air pressure
  inside the jug to offset the air pressure on the
  outside of the jug!

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The experimental observations about the behavior
of gases discussed so far can be explained with a
simple theoretical model known as the
kinetic molecular theory
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This theory is based on the following postulates,
or assumptions
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• Gases are composed of a large number of particles
  that behave like hard, spherical objects in a
  state of constant, random motion.
• These particles move in a straight line until
  they collide with another particle or the walls
  of the container.
• These particles are much smaller than the
  distance between particles. Most of the volume of
  a gas is more of an empty space.

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1. There is no force of attraction between gas
   particles or between the particles and the walls
   of the container.
2. Collision between gas particles or collision with
   the walls of the container are perfectly elastic.
   None of the energy of a gas particle is lost when
   it collides with another particle or with the
   walls of the container.
3. The average kinetic energy of a collection of
   gas particles depends on the temperature of the
   gas and nothing else.

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Applications on atmospheric pressure

• Application of atmospheric pressure ionization
  HPLC-MS-MS for the analysis of natural products
•   
• The development of techniques utilizing
  atmospheric pressure ionization, namely
  atmospheric pressure chemical ionization (APCI)
  and electrospray ionization (ESI), has pioneered
  the coupling of liquid chromatography (HPLC) with
  mass spectrometry in recent years. Both ESI and
  APCI generate ions from polar and labile
  biomaterials with remarkable ease and efficiency.
  In particular, the use of HPLC with tandem mass
  spectrometry (MS-MS) opens further dimensions in
  the field of bioorganic analysis. Thus,
  HPLC-MS-MS provides the tools for direct
  elucidation of the structure and variety of polar
  natural compounds in complex matrices. In order
  to develop efficient and straightforward
  strategies for the analysis of polar natural
  products, the potential and the limitations of
  these hyphenated analytical techniques are
  discussed using heterocyclic aromatic amines,
  fumonisins, acylated glycoconjugates and
  regioisomeric fatty acid hydroperoxides as
  examples.
•  

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Instruments for measuring gas and atmospheric
pressure

• Barometer

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Effects of altitude on atmospheric pressure

• Immediate effects
• Hyperventilation
• Fluid loss (due to a decreased thirst drive and
  decrease in ADH)
• Increase in heart rate (HR)
• Slightly lowered stroke volume

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• Longer term effects
• Lower lactate production (because reduced glucose
  breakdown decreases the amount of lactate
  formed).
• Compensatory alkali loss in urine
• Decrease in plasma volume
• Increased Hematocrit (polycythemia)
• Increase in RBC mass
• Higher concentration of capillaries in skeletal
  muscle tissue
• Increase in myoglobin
• Increase in mitochondria
• Increase in aerobic enzyme concentration
• Increase in 2,3-BPG
• Hypoxic pulmonary vasoconstriction
• Right ventricular hypertrophy

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• Ventilatory acclimatization
• The immediate effect of decreased pressure causes
  decreased partial pressure of oxygen. Resulting
  hypoxemia, sensed by the carotid bodies, causes
  hyperventilation. However, hyperventilation also
  causes the adverse effect of respiratory
  alkalosis, inhibiting the respiratory center from
  enhancing the respiratory rate as much as would
  be required.
• Gradually, the body compensates for the
  respiratory alkalosis by renal excretion of
  bicarbonate, allowing adequate respiration to
  provide oxygen without risking alkalosis. It
  takes about 4 days at any given altitude and is
  greatly enhanced by acetazolamide.3
• Inability to ventilatory acclimatizize can be
  caused by inadequate carotid body response or
  pulmonary or renal disease.3