Show n mk 4 11 ap AT A 4 awil covin A otye donvin i kp I 1 uart IJ A mw foa weekly guide to science HOW MUCH AIR DO YOU BREATHE the lungs of an average man will hold about ten pints but they are seldom as full as this unless you take a very deep breath usually they hold about six pints and only about one pint Is br breathed eath in and out at each breath ordinary people breathe about twenty times a minute so EO you use about twenty pints ot of air per minute or gallons per hour WHAT CONTROLS THE NUMBER OF TIMES YOU BREATHE IN A MINUTE A nerve center in the lower part of tho the brain which Is extremely sensitive to the amount ol of calbon cairon dioxide in the blood II if there Is more carbon dioxide than there ought to be this center sends out nerve messages to the muscles ot of the chest and makes you breathe taster faster so so that the lungs will get more fresh air and the carbon dioxide will be carried away faster WHY DO YOU GET SHORT OF WHEN YOU RUN running requires more energy the ving living cells mainly in the muscles work taster faster end and make more carbon dioxide they may make it so BO tast fast that the lungs cannot get rid ot of it properly the nerve center in your brain gets alarmed and makes you breathe taster faster and faster so BO that you pant HOW ARE ABE THE LUNGS PROTECTED AGAINST DUST IN TH THEAIR EAlR the tubes leading to the lungs are lined with a rembrance mem brance which produces a thick fluid all over its surface the dust particles stick to this the membranes mem brance has on its surface millions ol of short hair like projections project lona which are continually waving backward and to forward r these waving hairs gradually force the sticky fluid arid and the dust particles caught by it back into the throat where the dust will do no harm WHY CAN PEOPLE WHO HAVE BEEN apparently DROWNED BE REVIVED BY artificial respiration lack of air does not cause actual death until the tissues of the body have been without oxygen tor for some time and have suffered sult ered serious chemical chan changes gesas as a result it you restore breathing a artificially artl fici fic ally lally before these changes have had bad time to happen the thel tissues will recover and no harm will be done IS IT TRUE THAT A DROWNING PERSON ALWAYS COMES UP THREE TIMES X no the number ot of times he comes up of it at all will depend on the circumstances on his strength on the weight ot of his bis body on whether the water is salt or fresh on the currents etc WHY DOES THE BODY PERSPIRE WHEN IT IS overheated this Is a device tor for keeping the body temperature from getting too high the perspiration evaporates and that cools us ott off because of the large amount of beat which always Is absorbed when water changes from a liquid into a gas WHY DO WE FEEL COOLER WHEN RIDING IN AN automobile THAN WE DO WHEN SITTING STILL THOUGH TUE THE AIR ITSELF IS NO COOLER because the breeze created by the rapid motion of the automobile evaporates the perspiration more quickly and therefore absorbs heat from us at a taster faster rate WHY DO WE HIVE II 11 I 1 VI TO DRINK WATER two thirds of the body Is water nearly all the chemical changes which go on in the body take place in solution in water and will not take place any other way water Is being continually lost from the body as perspiration and this loss must be made up by the water we drink WHY DOES THE DOCTOR TAKI TAKE I 1 YOUR temperature WHEN YOU ARE ILL the normal t temperature empera ture ot of the human body Is 98 4 degrees fahrenheit and it contains regulating me mechanisms machanis chanis ins which keep the temperature very constant at this point any rise or fall of temperature means that something Is seriously asly wron wrong g so this Is one of mhd first signs that the doctor looks for or WHAT IS THE HIGHEST temperature TUREA A PERSON CAN STAND it if the temperature ot of the body itself gets above degrees even tor for a short time death Is nearly certain even degrees is dangerous the brain stops working at this point A person can withstand an outside temperature much higher than this because the body itself does not get hot in death valley men can work in a temperature of degrees even degrees has been observed but the copious perspiration and its quick evaporation due to the dryness of the air keep the body much cooler than this WHY DO DIFFERENT RACES HAVE DIF DIFFERENT COLORED SKIN scientists suppose that it Is because the various races have lived in different climates for instance the negro race has probably lived tor for millions of years in hot and sunny parts of the earth the long continued exposure to sunburn has darkened their skins WHAT ARE CORNS when the skin on oil the hands or feet is rubbed or pressed a good deal the living cells in it grow and m multiply u estape lueata 7 in order to protect the soft tissues u beneath this Is what makes calloused cal louses and horny borny spots but sometimes the growing skin cells make a mistake and grow inward in tad of outward atward D then they press against the tender tissues underneath nd and this makes a corn |