Environmental Biophysics The Interaction of Mechanical

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Environmental BiophysicsThe Interaction of
Mechanical Meteorological Factors With Human
Body.

• Ján Jakuš

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Physical Factors 1. The Effects of Gravity

• Gravity- (Earth)- affects the body with force 1g.
• Gravity is responsible for Hydrostatic pressure
  of body fluids PH density (?). gravity (g)
  .height (h)
• - just valid for persons in an upright
  position
• Because a gravity, the higher blood pressures are
  below the heart, the lower values are above the
  heart. The pressure difference caused by gravity
  is 0.77 mm Hg/ 1 cm of a vertical distance
• Thus, in the foot arteries around the ankle
  there is BPa 180 mmHg, at a level of heart
  100 mmHg, and in the brain arteries 70 mmHg.
  Similarly in foot veins BPv 80 mm Hg, at a
  heart 0 mmHg, in brain veins- 10 mmHg
  (negative subatmospheric)

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Blood Pressures under Orthostasis
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2. Effects of Overloading- acceleration, or
deceleration. Weightlessness state.

• Overloading 1. longitudinal- positive ( g ) It
  is directed from top to botom, i.e in the
  opposite way to the upward movement
• 
  - negative (- g ) It acts from botom to a top,
  in the apposite way to the dow-nward movement
• 2. transversal
  (acts from the back to the chest or from the
  chest to back), in the oppo-site way to the
  movement
• Positive overloading ( acts from top to botom)
  when rocket moves upwards, then g pushes blood
  from head to the feet. The signs of brain
  ischeamia develop (i.e.white vision-because
  retinal vessels are poorly supplied, or an
  unconsciousness) Overloa-ding 5g may increase
  a blood pressure in feet up to 400 mm Hg)
  Protection double walled antigravital dress with
  compressed air.

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Negative overloading (- g )

• It is directed from botom to a top, e.g.during
  len-ding of a rocket, or in the fast elevators
  moving downwards. Negative - g drives blood from
  feet to head, the brain and retinal vessels are
  overfilled and thus symptoms of red vision
  appear.
• Transversal overloading
• Humas are able to accept better transversal than
  longi-tudinal overloading. This overloading acts
  either from the chest to back ( astronauts can
  keep even 17g/ per 4 min), or from the back to
  chest (16 g / 3 min). Therefore astronauts keep
  laying position both at start and during lending
  of the rocket
• Space siccness- kind of disorder during space
  mis-sion with symptoms (nausea, vomiting,
  headache, etc.)

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Weightlessness state-because no gravity
astronauts may suffer from a loss of
minerals(decalcification), (loss of muscle tissue
(reduce of body mass), dehydratation( water
deficiency)
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3. Effects of a Low Barometric Pressure
(Hypobaria)

• It happens when one climbs to the altitudes above
  3,000- 8,000 m. Composition of air (Volume of
  O2, N2..) at those levels does not change, but a
  total barometric pressure drops. Hence, also
  par-tial pressures of O2, N2... fall down.

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Altitude Barom.P PO2 in air P02
in lungs (m ) (mmHg) (mmHg)
(mm Hg)
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The Effects of Hypoxia-appears first at
altitude of 3,500 m ( appreciable handicap )
and at level of approx. 6,000m as a serious
handicap or colapse . The reason is acute hypoxia
(a steep fall of P02)
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Symptoms of hypoxia. The Mountain
Disease,Acclimatization

• The signs of chronic hypoxia Breatlessness,
  whirling sensation, dizzeness, nausea, vomiting,
  tachy-cardia, loss of orientation are typical
  for the Mauntain Disease
• The signs of acute hypoxia Colabs, Loss of
  Vigility, Pulmonary Oedema, Death (if no oxygen
  in tank )
• Acclimatization is needed for climbers to
  prevent hypoxic symptoms. During 3 weeks of
  climbing they are not allowed to climb very
  fast,but must take some breaks for two- three
  days. Hence, hormon ERYTROPOETINE is released
  from kidneys, and in turn, it stimulates the
  pro-duction of red blood cells in bone marrow.
  Thus, hypo-xia,caused by hypobaria, is balanced
  by the rise of red blood cells, in order to
  assure a sufficient amount of O2
• for tissues.

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4. Effects of High Water and Air Pressures
(Hyperbaria)

• During diving - ambient pressure of water
  gra-dually rises up by the 1 atm ( 760 mmHg )
  for every 10 m of water depht. This pressure
  com-presses the divers body, and in order to
  breath and retain alive, the diver must inhale
  the com-pressed air (containing O2 and/or
  Helium) from the tank.

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Decompression Disease

• Inhalation the compressed air ( 3-4 atm)
  from the tank balances the ambient water
  pressure. However, because air in tank is under
  high pressure, this results in a rise of
  physically dissolved N2, O2, CO2 in blood plasma.
  Because O2 is consumed, CO2 is removed, just N2
  dissolves in the brain and fat tissues. Thus
  symptoms of nitrogen narco-sis appear. At it
  diver loses orientation and feel happy (as
  after an alcohol consumption). Problem is when he
  wants to return back to see level fastly. Then
  the symp-toms of decompression disease develop.
  The point is that N2 bubbles dissolved in tissues
  and in blood RELEASE and may cause an nitrogen
  pulmonary embolization (i.e.obst-ruction of lung
  and brain vessels by nitrogen bubbles) and also a
  death of diver. Decompression physically
  resam-bles to an opening of bottle with soda,
  when bubbles escape, because the high air
  pressure falls to normal one.

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Signs of Decompression Disease, Treatment,
Hyperbaric chamber

• - bad pain in the joints and bones,
• - strong itching of the skin,
• - lung and heart disorders with collapse
• - even death - because pulmonary oedema
• How to prevent Decompression Disease?
• instead of air, tank is filled with O2 and Helium
• diver must take some breaks when turning back to
  see level (e.g. whe he had dived to 60 m and
  worked there 30 min, he must care for
  physiological decompression i.e. move upwards
  step by step taking totally 90 min. with
  forceful active hyperventilation during breaks (
  N2 )
• Treatment
• Fast Recompression in Hyperbaric Chamber and then
  Slow Decompression

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Hyperbaric Chamber Hyperbaric Oxygenation

• It is a special device for treatment of
  Decompre-ssion disease, Carbone monoxide
  poisoning and Clostridial infections ( Clostridia
  are bacte-ria very sensitive to oxygen, which
  kills them). Air (and 02) is under high pressure
  (3- 5 atm). Point Physically dissolved O 2 and
  Henrys Law