Environmental Biophysics The Interaction of Mechanical & Meteorological Factors With Human Body .

1. Environmental BiophysicsTheInteraction of Mechanical&Meteorological Factors With Human Body. Ján Jakuš

2. Physical Factors: 1. The Effects of Gravity Gravity- (Earth)- affectsthe body withforce 1g. GravityisresponsibleforHydrostaticpressureof body fluids: PH = density (ρ). gravity (g) .height (h) -justitisvalidforpersons in anuprightposition Because a gravity, thehigherbloodpressures are belowtheheart,thelowervalues are abovetheheart. Thepressuredifferencecaused by gravityis: 0.77 mm Hg/ 1 cm of a verticaldistance Thus, in thefootarteriesaroundtheanklethereisBPa = 180 mmHg, at a levelofheartV.= 100 mmHg, and in thebrainarteries = 70 mmHg. Similarly in footveinsBPv= 80 mm Hg, ata heartatrias = 0 mmHg, in brainveins= - 10 mmHg (negative)

3. Blood Pressures under Orthostasis

4. 2. Effects of Overloading- acceleration, or deceleration. Weightlessness state. Overloading: 1.longitudinal - positive (+ g )Itisdirectedfromtop to botom, i.e in theoppositeway to theupwardmovement - negative (- g )Itactsfrombotom to a top, in theoppositeway to thedow-nwardmovement 2. transversal(actsfromtheback to thechest or fromthechest to back), in theoppositeway to themovement Positive+ overloading(actsfrom top to botom)whenrocketmovesupwards, then + g pushesbloodfromhead to thefeet. Thesignsofbrainischeamiadevelop (i.e.whitevision-becauseretinalvessels are poorlysupplied, or anunconsciousness)Overloading + 5g mayincreasearterialbloodpressure in feetup to 400 mm Hg.Protection:astronauts are wearingdoublewalledantigravitaldresswithcompressedair.

5. Negative overloading (- g ) Itisdirectedfrombotom to a top, e.g. duringlendingof a rocket, or in thefastelevatorsmovingdownwards. Negative - g drivesbloodfromfeet to head, thebrain and retinalvessels are overfilledwithblood and thussymp-tomsofredvisionappear. Transversaloverloading Humans are able to acceptbetterkindoftransversalthanlongitudinaloverloading. Thisoverloadingactseitherfromthechest to back( astronautscankeepeven 17g/ per 4 min withoutunconsciousness)), orfromtheback to chest (16 g / 3 min). Thereforeastronautskeeplayingpositionbothatstart and duringlendingoftherocket Spacesiccness-kindofdisorderduringspacemissionwithsymptoms (nausea, vomiting, headache, etc.)

6. Weightlessnessstate-because no gravity in SPACE astronautsmaysufferfrom SYMPTOMS: a lossofminerals (decalcification),(lossofmuscletissue (reduce a body mass), dehydratation( waterdeficiency)

7. 3. Effects of a Low Barometric Pressure (Hypobaria) Ithappenswhenoneclimbs to thealtitudesabove 3,000- 8,000 m. Compositionofair ( O2, N2, ..)atthoselevelsdoesnotchange, but a totalbarometricpressuredrops. Hence, alsopartialpressuresof O2, N2...falldown.

8. Altitude Barom.PPO2 in airP02 in lungs(m)(mmHg)(mmHg)(mm Hg)

9. 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)

10. Symptoms of hypoxia. The Mountain Disease,Acclimatization Thesignsofchronichypoxia: Breatlessness, whirlingsensation, dizzeness, nausea, vomiting, tachy-cardia, lossoforientation – are typicalfortheMauntainDisease Thesignsofacutehypoxia:Colabs, Lossof , consciousness,PulmonaryOedema, Death (if no oxygen in tank) Acclimatization: isimportantforclimbers to preventhypoxicsymptoms. Duringclimbingthey are notallowed to climbquickly ,butmusttakesomebreaksfortwo- threedays. Hence, hormon ERYTROPOETINE isreleasedfromkidneys, and in turn, itstimulatestheproductionofredbloodcells in bone marrow. Thus, hypoxia,caused by hypobaria, isbalanced by theriseofredbloodcells, in order to assure a sufficientamountof O2 fortissues.

11. 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 diver´s body, and in order to breath and retain alive, the diver must inhale the com-pressed air 3-4 atms (containing O2 and/or Helium) from the tank.

12. Decompression (Cushion) Disease Inhalationthecompressedair ( 3- 4 atm)fromthe tank balancestheambientwaterpressure. However, becauseair in tank isunderhighpressure, thisresults in a riseofphysicallydissolved N2, O2, CO2 in bloodplasma ( Henry´sLaw.) Because O2isconsumed, CO2 isremoved, just N2 dissolves in thebrain and fattissues. Thussymptomsof „nitrogennarcosis“appear. Atitdiverlosesorientation and feel „happy“ (asafteranalcoholconsumption). Problemiswhenhewants to returnbacktoseelevelquickly. Thenthesymptomsofdecompressiondiseasedevelop. The point isthat N2bubblesdissolved in tissues and in blood RELEASE and maycauseannitrogenembolization (i.e.obstructionoflungs and brainvessels by nitrogenbubbles) and also a deathofdiver. Decompressionphysicallyresembles to anopeningofbottlewithsoda,whenbubblesescape,becausethehighairpressurefalls to normalone.Thisphysicaleffectisnamed EVASION.

13. Signs of Decompression Disease, Treatment, Hyperbaric chamber - badpain in thejoints and bones, - strongitchingofthe skin, - lungs and heartdisorderswithcollapse - evendeath - becausepulmonary and brainoedema How to preventDecompressionDisease? • insteadofair(O2 + N2 + CO2..), tank isfilledwithmixtureof O2and Helium • divermusttakesomebreakswhenturningback to seelevel (e.g. whenhe had dived to 60 m and workedthere 30 min, hemustperformthe „physiologicaldecompression“ i.e. hemovesupwardsslowly- step by step- takingtimetotally 90 min. withforcefulactivehyperventilationduringbreaks (CO2 and N2 are released) Treatment • ThefastRecompression in HyperbaricChamber and thenSlowDecompression

14. Hyperbaric Chamber & Hyperbaric Oxygenation Itis a special device fortreatmentofDecompre-ssiondisease, Carbonemonoxidepoisoning and Clostridialinfections ( Clostridia are bacte-riaverysensitive to oxygen, whichkillsthem). Air (and 02)withinchamberisunderthehighpressure (3- 5 atm). Point: Physicallydissolved O 2 risesupbecausetheHenry´sLaw

15. Thank You For Attention