MARY CLAIRE PADDOCK

THE EXCRETORY SYSTEM

THE PURPOSE

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.

THE ORGANS INVOLVED THERE ARE SEVERAL ORGANS THAT WORK

TOGETHER IN THE EXCRETORY SYSTEM INCLUDING THE KIDNEYS, URETER, BLADDER, AND URETHA.

THE PROCESS

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 KIDNEY

THE PROCESS

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 25-30 CM LONG AND 3-4 MM IN DIAMETER.

THE URETER

THE PROCESS

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 BLADDER

THE PROCESS

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.

THE EXCRETORY SYSTEM

INTERACTING WITH OTHER SYSTEMS

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.

BIBLIOGRAPHY

http://www.biology4kids/files/systems excretory.html

http://www.cic-carcas.org/departments http://www.fi.edu./learn/heart/systems http://www.teachnet

.com/lessonplans/science/biology/theexcretorysystem

http://www.webmd.com/urinary/bladder

http://www.wikipedia.org/wiki/renalartery