 HIDDEN THROUGHOUT YOUR BODY ARE DANGEROUS POISONS THAT MUST BE REMOVED IN ORDER FOR YOU TO SURVIVE. THE PROCESS OF EXCRETION INVOLVES FINDING AND REMOVING WASTE MATERIALS PRODUCED BY THE BODY.

 THERE ARE SEVERAL ORGANS THAT WORK TOGETHER IN THE EXCRETORY SYSTEM INCLUDING THE KIDNEYS, URETER, BLADDER, AND URETHA.

 BLOOD IS SUPPLIED TO THE KIDNEYS BY THE RENAL ARTERY. ONCE THE BLOOD ENTERS THE KIDNEYS, THE FILTERING PROCESS BEGINS. WATER AND OTHER WASTE PRODUCTS ARE REMOVED FROM THE BLOOD BY MICROSCOPIC STRUCTURES WITHIN THE KIDNEYS CALLED NEPHRONS. EACH KIDNEY CONTAINS OVER ONE MILLION NEPHRONS. THIS ORGAN IS ABOUT THE SIZE OF A HUMAN FIST.

 THE WASTE FILTERED FROM THE BLOOD FORMS A LIQUID CALLED URINE. THE KIDNEYS FUNNEL THE URINE INTO THE BLADDER ALONG TWO SEPARATE TUBES CALLED URETERS. URETERS ARE TUBES MADE OF SMOOTH MUSCLE FIBERS THAT PROPEL URINE FROM THE KIDNEYS TO THE BLADDER. IN ADULTS, URETERS ARE USUALLY CM LONG AND 3-4 MM IN DIAMETER.

 FROM THE URETERS, THE URINE IS FUNNELED INTO THE BLADDER. THE BLADDER STORES THE URINE UNTIL MUSCULAR CONTRACTIONS FORCE THE URINE OUT OF THE BODY THROUGH THE URETHA. EACH DAY, YOUR KIDNEYS PRODUCE ABOUT 1.5 LITERS OF URINE. ALL OF IT NEEDS TO BE REMOVED FROM YOUR SYSTEM. WHEN EMPTY, THE BLADDER IS ABOUT THE SIZE AND SHAPE OF A PEAR.

 THE RENAL VEINS DRAIN THE KIDNEYS AND CARRY THE FILTERED BLOOD TOWARDS THE HEART. THEY CONNECT THE KIDNEY TO THE INFERIOR VENA CAVA. BECAUSE THE INFERIOR VENA CAVA IS ON THE RIGHT HALF OF THE BODY, THE LEFT RENAL VEIN IS GENERALLY THE LONGER OF THE TWO.

 ALL BLOOD THAT CIRCULATES THROUGHOUT THE BODY PASSES THROUGH ONE OF THE TWO KIDNEYS. THE EXCRETORY SYSTEM CLEANS THE BLOOD OF WASTE PRODUCTS PRODUCED BY THE SKELETAL, MUSCULAR, DIGESTIVE, RESPIRATORY, CIRCULATORY, AND NERVOUS SYSTEMS.

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