Excretory System


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Excretory System

  1. 1. T- 1-855-694-8886Email- info@iTutor.comBy iTutor.com
  2. 2.  The human excretory system functions to remove wastefrom the human body. During this process animals get rid of nitrogenous wasteproducts of metabolism, including ammonia, urea, anduric acid. Although excretory systems are diverse, nearly all produceurine in a process that involves several steps.KidneysUrethrasUrinary bladderUrethraOrgans of theExcretory System© iTutor. 2000-2013. All Rights Reserved
  3. 3. 1. Filtration: The excretory tubule collects filtrate from the blood.Water and solutes are forced by blood pressureacross the selectively permeable membranes of acluster of capillaries and into the excretory tubule.2. Reabsorption: The transport epithelium reclaims valuablesubstances from the filtrate and returns them.3. Secretion: Other substances are extracted from body fluids andadded to the contents of the excretory tube.4. Excretion: The filtrate leaves the system and the body.© iTutor. 2000-2013. All Rights Reserved
  4. 4.  This system consists of specialized structures andcapillary networks that assist in the excretory process. The human excretory system includes the kidney andits functional unit, the nephron. The excretory activity of the kidney is changed byspecialized hormones that regulate the amount ofabsorption within the nephron.Bladder KidneysUrethraUretersMeatus© iTutor. 2000-2013. All Rights Reserved
  5. 5.  Located both sides of the spine betweenthoracic and lumbar vertebrae. Blood enters the kidneys through renalarteries and leaves through renal veins. Tubes called ureters carry wasteproducts from the kidneys to the urinarybladder for storage or for release.During urination, urine is expelled from the urinarybladder through the urethra.© iTutor. 2000-2013. All Rights Reserved
  6. 6. Flow of UrineFlow of UrineGlomerulusRenal TubulesRenal PelvisRenal CalicesUretersRenal cortexRenal capsuleRenal medullaUreterRenal veinRenal arteryNephron© iTutor. 2000-2013. All Rights Reserved
  7. 7. Parts of the KidneyKidneys filter about 1700 liters of blood daily in the average adult.Parts of the kidneys• Cortex-outer protective portion• Medulla-inner soft portion• Hilum-a depression located in the middle of theconcave side of the kidney where bloodvessels, nerves, and the ureters enter andexit the kidneys CortexMedullaHilum© iTutor. 2000-2013. All Rights Reserved The cortex is where the blood is filtered. The medulla contains the collecting ducts which carryfiltrate (filtered substances) to the pelvis. The pelvis is a hollow cavity where urine accumulatesand drains into the ureter.
  8. 8.  The functional units of the kidney are called nephrons. Nephrons are located in the renal cortex, except for theirloops of Henle, which descend into the renal medulla.Nephron© iTutor. 2000-2013. All Rights Reserved
  9. 9. Two partsa. Renal Corpuscle1. Bowman Capsule2. Glomerulusa. Fenestrae - pore in endothelial walls of glomerulus.b. Podocytes - specialized cells.c. Filteration slitsb. Renal Tubule - Series of single layer tubules1. Proximal Convoluted tubule2. Loop of Henle3. Distal Convoluted tubuleNephronKidneys are made up of nephrons. Blood enters the nephron, whereimpurities are filtered out and emptied into the collecting duct. Thepurified blood leaves the nephron through the renal vein.© iTutor. 2000-2013. All Rights Reserved
  10. 10. ArteryVeinLoop of HenleBowman’s capsuleGlomerulusCapillariesCollectingductTo the ureter© iTutor. 2000-2013. All Rights ReservedNephron
  11. 11.  The glomerulus is a mass of thin-walled capillaries. The Bowman’s capsule is a double-walled, cup-shapedstructure. The proximal tubule leads from the Bowman’s capsule tothe Loop of Henle. The loop of Henle is a long loop which extends into themedulla. The distal tubule connects the loop of Henle to thecollecting duct. Each nephron has its own bloodsupply: An arteriole A venule A network of capillariesconnecting themEach nephron releases fluidsto a collecting duct, whichleads to the ureter. © iTutor. 2000-2013. All Rights Reserved
  12. 12. Each kidney contains more than 1 million nephrons. Blood Flow through the KidneysBlood enters through the renal artery ArteriolesEach arteriole leads to a nephron Renal corpuscleThe glomerulus filters fluid from the blood, and is thefirst place where urine is formed in the kidneys.Blood flows through the glomerulus at a constant rate.Each glomerulus is surrounded by a capsule known asBowman’s capsule.Blood then passes into the renal tubules where somesubstances are reabsorbed and the remaining becomeurine.© iTutor. 2000-2013. All Rights Reserved
  13. 13. – As blood enters a nephron through thearteriole, impurities are filtered out and emptiedinto the collecting duct.– The purified blood exits the nephron through thevenule.How is blood filtered?The mechanism of blood purification involvestwo distinct processes:FiltrationReabsorption© iTutor. 2000-2013. All Rights Reserved
  14. 14. • Filtration– Passing a liquid or gas through a filter to remove wastesis called filtration.– The filtration of blood mainly takes place in theglomerulus.– The glomerulus is a small network of capillaries encasedin the top of the nephron by a hollow, cup-shapedstructure called Bowmans capsule.– Fluid from the blood flows into Bowman’s capsule.– The materials filtered from the blood includewater, urea, glucose, salts, amino acids, and somevitamins.– Plasma proteins, cells, and platelets remain in the bloodbecause they are too large to pass through the capillarywalls.© iTutor. 2000-2013. All Rights Reserved
  15. 15. • Reabsorption– Most of the material removed from the blood atBowmans capsule makes its way back into the blood.– The process in which liquid is taken back into a vesselis called reabsorption.– Almost 99% of the water that enters Bowman’s capsuleis reabsorbed into the blood.– When the filtrate drains in the collecting ducts, mostwater and nutrients have been reabsorbed into theblood.© iTutor. 2000-2013. All Rights ReservedGlomerulusAfferent arterioleEfferent arterioleBowman’scapsuleGlomerularFiltration
  16. 16.  Remaining material, called urine, is emptied into acollecting duct. Urine is primarily concentrated in the loop of Henle. The loop of Henle is a section of the nephron tubule inwhich water is conserved and the volume of urineminimized. As the kidney works, purified blood is returned tocirculation while urine is collected in the urinarybladder. Urine is stored here until it is released from the bodythrough a tube called the urethra.© iTutor. 2000-2013. All Rights Reserved
  17. 17. UretersPeristalsis, a rhythmiccontraction of the ureter smoothmuscle which helps to move theurine into the bladder.A tube approximately 6 to 7inches long attached to eachkidney. Made up of three layers oftissue Smooth muscle Fibrous tissue Mucous layerUreter© iTutor. 2000-2013. All Rights Reserved
  18. 18. Urinary BladderUrinary Bladder•Hollow, muscular organ thatstores urine•Sphincter muscles hold theurine in place•Holds 300 to 400 milliliters ofurine before emptying•Walls contain epithelial tissuethat stretch to allow the bladderto hold twice its capacityUrethraProstateglandUreterUrinary bladder•The trigone is a triangular areaat the base of the bladder wherethe ureters enter and the urethraexits
  19. 19. UrethraUrethraFemale Urethra Male Urethra•Approximately 1.5inches long•Opens through themeatus•Approximately 8 inches long•Passes through three differentregions:Prostate glandMembranous portionPenisA tube of smooth muscle with a mucous lining that carriesurine from the bladder to the outside of the body.
  20. 20.  Tiny pores in the tubing allowsalts and small molecules topass through. Wastes diffuse out of theblood into the fluid-filledchamber, allowing purifiedblood to be returned to thebody.DialysisAirdetectorDialysismachineFresh dialysisfluidCompressed airVeinArteryShuntBlood pumpBlood in tubing flowsthrough dialysis fluidUsed dialysis fluid Blood is removed by a tube andpumped through special tubingthat acts like nephrons.
  21. 21. The EndCall us for moreInformation:www.iTutor.com1-855-694-8886Visit