Effects of atmospheric pressure on human It has now been proved in medical science of aviation and space that excessive heights above the Earth’s 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.
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 Earth’s surface, so as to make the pressure in them equal that on the Earth’s surface; otherwise passengers would lose consciousness.
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/cm 2 ; 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.
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. moleculesvolume
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 lb f ). The weight of a 1 m 2 (11 sq ft) column of air would be about 101 kN (10.3 t f ).Earth's atmospherehydrostatic pressureweightair elevationsea levelnewtonslb ft f
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?)
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!
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.
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!
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
This theory is based on the following postulates, or assumptions :
1.Gases are composed of a large number of particles that behave like hard, spherical objects in a state of constant, random motion. 2. These particles move in a straight line until they collide with another particle or the walls of the container. 3. These particles are much smaller than the distance between particles. Most of the volume of a gas is more of an empty space.
4.There is no force of attraction between gas particles or between the particles and the walls of the container. 5.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. 6. The average kinetic energy of a collection of gas particles depends on the temperature of the gas and nothing else.
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.
Instruments for measuring gas and atmospheric pressure Barometer
Effects of altitude on atmospheric pressure Immediate effects Hyperventilation Fluid loss (due to a decreased thirst drive and decrease in ADH) Fluid loss ADH Increase in heart rate (HR) Increase in heart rate Slightly lowered stroke volumestroke volume
Longer term effects Lower lactate production (because reduced glucose breakdown decreases the amount of lactate formed).lactate Compensatory alkali loss in urinealkali Decrease in plasma volumeplasma Increased Hematocrit (polycythemia)Hematocritpolycythemia Increase in RBC massRBC Higher concentration of capillaries in skeletal muscle tissuecapillariesskeletal muscle Increase in myoglobinmyoglobin Increase in mitochondriamitochondria Increase in aerobic enzyme concentrationaerobic Increase in 2,3-BPG2,3-BPG Hypoxic pulmonary vasoconstriction Hypoxic pulmonary vasoconstriction Right ventricular hypertrophy Right ventricular hypertrophy
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. partial pressurehypoxemia carotid bodiesrespiratory alkalosisrespiratory center 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. acetazolamide  Inability to ventilatory acclimatizize can be caused by inadequate carotid body response or pulmonary or renal disease.