Show YOURSELF tit TD TT by WILFRED ALFRED LJ T GRENFELL nd and YOUR BODY I 1 THE PUMP AND PIPES AOTA ct MAIN MAIM PIPE TO rca BODY BI BLOOD SECOND CHAMBER tr ALONG MUSCLE WE CID 3 ED valvik CH CHAMBER A M B E ft 1 0 CLEAN sla V VEW eha FROM luwi luna 13 j UT father how does the L lymph gei get back every 1 time you move a muscle or breathe you squeeze it out ot of tile the spaces which end rid in openings into special little ies esela eig valves keep it from ever getting back so on and on it has to go into a large pipe which empties at last into the blood through a hl big vein in the neck near the heart it 1 is pushed on also a little by the heart and sucked on by the current in the vein moreover it Is helped tilon along by the fact that it Is different in composition from the other fluids fluid and zo so passes out olit into any fluid next to it IL this process Is called diffusion cut but father ant makes the blood go round to all tile the cells 1 I dont bondor you ask that Is a real job I wt it for you see the cells cannot live as we can on me meals als throe three times a day they anu must t get air rind and food brought to to them dav and night and all the time so long lone as they get that they do not care where they are and they will therefore prow outside the body just us as well as inside if you also krep keep them then you must remember what in an awful I 1 lot of pipes we must murt have to reach all the cells and what an awful heap berill of pumping we shall have to make our pump do moreover ours are far the most moot wonderful pipes in the world th they ey grow bigger or smaller just as they are told there Is a ernp in the pipe what makes the trap shut why because it Is a valve valre or trap which opens only one wiy and the rubber springing lip again sucks or pulls palls up the lid and when you ton squeeze down the lid aln closes es again it is exactly like tile the trapdoor trap trop door of our attle attic and dont you vou reme remember luber the one we made to pump out our bout boat with a woolen wooden flap a leather hinge a heavy cont coat of lead fixed on the trapdoor trap door to shut it down that thai work well sill splendidly end I 1 oly well the heart has invented tar fir better valrea for itself and it has built two bulbs to make it throw stronger than it could with one and to give a more even fl lot oIn ting current not one that jerks well take the best pump in the world a good heart so we have two two cylinder engines as you see in the picture one set pumps the impure blood into the lung and the other pumps the pure blood into the body this pure blood car carries carlip rip the food and air the pumps lie side by side and are joined tn together gether making a shape something like the see are of hearts they throw twenty tumbler fuls in a minute and all the blood in the body in one and one halt half minutes eu bul it if you run a race or climb a high ghigli mountain fill all the blood in your body may puss pass through in one minute the first pipes pipe pre large and are called arteries or air thoroughfares they pet get smaller and smaller anaf and smaller maller like allee alice in wonderland till they tire are mere hair til tubes loes or e apilla rles and then these join together and get bigger and bigger again till they are pipes called veins the arteries ore are strong and thick and very elastic cun can you guess why because the heart pumps hard right into them yes that Is if part of the reason but there Is another and a very clever reason you know those squeaker toys with elastic bags that you blow up lip dont you what makes them so go on squeaking gf be long oh the elastic bag squeezes the air out scowl slowly y through the pipe exactly so go that Is why th the 0 arteries artere I 1 a are so elastic because 1 in between the strokes of the pump they are squeezing out through the pipes the blood which was forced into them their the splendid result Is that the stream flows onward evenly all the time through the hair tubes into the veins and back bach again to tho the heart on its never ending round the veins are soft and have thin walls but they have fine valves to help the blood not to rush back into the hair tubes sometimes those valves give out they are not very strong and they have a heavy weight on them if 1 they happen to be in the legs of a fat per son then what happens Is this the blood does docs run back and leaks leak out everywhere and the legs s well swell up ond and turn blue and hurt and tile the poor man cannot get his boots on where Is IB your heart can you feel it surely what Is it doing Thum thumping pin 11 how flow many thumps to the alere Is my watch count them seventy now lift this chair up five birnes now count again how many thumps now eighty right every bit of work you see gives our hearts more to do if you listen carefully you can hear that the pump rests for a fraction of oc a second after every two beets beats all the rest it eer cier takes less jess than ten minutes in twenty four tl hours urs like every other pump we ahall have to grease it otherwise it will get hot and jam like the engine we will hang it tn in an oil bag that thai will help also to keep it in its place the bag Is slung by fine ties inside the box made by the ribs inside the bag there Is a beautiful soft moist lining very thin and covered with the buz samo cells which prevent blood clotting in tile the pipes the cells lining the oil bag must of course manufacture their own oil I 1 wish the lining of our gasoline tank would do liken ise every dog has to have a 8 name to tell it from other dogs and all these parts of the body have latin names or greek ones they are very ersy easy it if you know latin and greek but we do not really need them the big pipes which are elastic remain open find and are full of air after the body Is dead because of course the elastic has squeezed all the blood out of them but that made doctors thlik think that they always carried sir air tind and to BO they called them ncr ferfes and ami we i still call them by the old name just as the first bulb of tile the heart Is called tile tho auricle which just means ear and the second bulb Is called the ventricle which only means belly thus tile the pipe to the lungs Is called tile lung pipe or pulmonary artery and the pipe that carries blood to the whole boda Is called the aorta or carrier for the hearts guidance local offices exist both in and on its walls some messages come collie direct by special wires all the way from the central office in the brain these long wires are called the wanderers it odd these only bring messages to say go slow brother exactly like the slang phrase keep your shirt f on or keep cool all the messages to speed up or hurtle hu itle come from offices close to the heart and connected directly with the big wires in the spine right alongside the heart the hair tubes are so go fine that it takes two to three thousand side by side to measure one inch As people get old the arteries get very chalky a and rid break easily when an old person has a stroke it Is because an artery has broken inside the licad office la in the brain and the managers are drowned just so EO the body dies eventually but it if we are careful not to overeat and if we avoid toxins or poisons like alcohol there Is no rea son eon that the pipes should not last a hundred bund reil years easily a by br the bell it 1 |