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

Physical Factors: 1. The Effects of Gravity Gravity- (Earth)- affects the body with force 1g. Gravity is responsible for Hydrostatic pressure of body fluids: P H = density (ρ). gravity (g).height (h) - just valid for persons in an upright position - 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 BP a = 180 mmHg, at a level of heart = 100 mmHg, and in the brain arteries = 70 mmHg. Similarly in foot veins BP v = 80 mm Hg, at a heart = 0 mmHg, in brain veins=- 10 mmHg (negative subatmospheric)

Blood Pressures under Orthostasis

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 - 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 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.

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. 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 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.)

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)

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 O 2, N 2..) at those levels does not change, but a total barometric pressure drops. Hence, also par- tial pressures of O 2, N 2... fall down.

Altitude Barom.P PO 2 in air P0 2 in lungs (m ) (mmHg) ( mmHg) (mm Hg)

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 P0 2 )

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 ) 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 O 2 for tissues. for tissues.

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 (containing O 2 and/or Helium) from the tank.

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 N 2, O 2, CO 2 in blood plasma. Because O 2 is consumed, CO 2 is removed, just N 2 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 N 2 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. 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 N 2, O 2, CO 2 in blood plasma. Because O 2 is consumed, CO 2 is removed, just N 2 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 N 2 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.

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 O 2 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 ( N 2 ) Treatment -Fast Recompression in Hyperbaric Chamber and then Slow Decompression

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 0 2 ) is under high pressure (3- 5 atm). Point: Physically dissolved O 2 and Henry´s Law