The Excretory System

1. The Excretory System

2. Purpose • Contributes to homeostasis • Regulates internal environment by eliminating metabolic waste products: • Volume • Electrolyte composition • pH

3. Waste Products • Some are metabolic • E.g. Water, salts, CO2, and urea • Urea is a toxic compound that is produced when amino acids are used for energy (contain nitrogen).

4. Three Organs Kidneys Lungs Skin

5. 1. Kidneys • Main organs of excretion. • Remove excess water, urea & other excess mineral wastes from the body. • Act as filters to remove wastes that are collected and transported by the blood. • E.g. Surplus in water or electrolyte (salt) in blood = kidneys excrete in the urine.

6. 2. Lungs • Every time we exhale, we get rid of small amounts of water vapor and CO2. • CO2 is the waste product of cells that must be removed from the body so you can take in oxygen.

7. 3. Skin • Excretes excess water, salts, and small amounts of urea through sweating.

9. The Urinary System • Made up of: • Left and right kidneys • Ureters • Bladder • Urethra • Removes wastes and toxins from the blood and produces urine. • Urine: made of water, excess salts, & urea

10. Kidney Structure • Bean shaped • Either side of the spinal column, near lower back • Size of your fist • Each are attached to a renal artery & a renal vein

11. Renal Vessels • Renal artery – blood from aorta • unfiltered and full of bodily wastes • Renal vein – filtered blood http://www.yoursurgery.com/ProcedureDetails.cfm?BR=1&Proc=69

12. Ureters and Bladder • Ureter leaves each kidney with fluid containing excess water, salts, urea & other waste products • Ureters lead to the bladder; liquid wastes are deposited/stored here • Expulsion of wastes controlled by specific sphincter muscles – voluntary control. http://www.etsy.com/listing/70476539/kidneys-crochet-plush-with-ureters-and http://www.emedicinehealth.com/prolapsed_bladder/page17_em.htm

13. Kidney Regions • 2 distinct regions: • Inner Part: Renal Medulla • Outer Part: Renal Cortex

14. Nephrons • In the renal cortex • Working parts of the kidney • Each acts as an individual unit of filtration • About 1 million nephrons per kidney

15. http://www.agefotostock.com/age/ingles/enam01b.asp?foto=13173541&key1=&foto_clave=BSI-3555309&famp=1http://www.agefotostock.com/age/ingles/enam01b.asp?foto=13173541&key1=&foto_clave=BSI-3555309&famp=1

16. FYI The kidneys receive approximately 10% of the blood that is pumped out of our heart every minute. Adult kidneys filter approx. 180L of blood daily.

17. Filtration-Reabsorption-Secretion-Excretion

18. 1. Filtration - Bowman’s Capsule (BC) • -Hollow bulb surrounding ball of capillaries (Glomerulus) http://www.pitt.edu/~anat/Abdomen/Kidneys/Kidneys.htm

19. http://www.as.miami.edu/chemistry/2086/chap26/chapter%2026-new_part1.htmhttp://www.as.miami.edu/chemistry/2086/chap26/chapter%2026-new_part1.htm

20. Filtration (cont’d) • Blood enters via renal artery • Blood filters through permeable walls under pressure • Filtered materials (urea, glucose, salts, & some vitamins) are called filtrates. http://physrev.physiology.org/content/88/2/451

21. Filtration (cont’d) • Platelets, red and white blood cells remain in the blood (too large to pass) • Adult kidneys filter approx. 180L of blood daily.

22. Filtration-Reabsorption-Secretion-Excretion

23. 2. Re-Absorption - Tubules • Some filtrates reabsorbed by active transport • valuable & can’t be lost • Water returns to blood through osmosis • 99% of the water that is filtered out of BC is reabsorbed into your blood

24. Filtration-Reabsorption-Secretion-Excretion

25. 3. Secretion - Tubules • Excess fluid leaves BC & enters tubules • URINE. • First part – Proximal Convoluted Tubule (PCT). • carries fluid down into the Loop of Henle (LH).

26. 3. Secretion - Tubules • Urine concentrated in the tubule at the LH. • i.e.water reabsorbed • Urine moves up Distal Convoluted Tubule (DCT) & meets ureter

27. Filtration-Reabsorption-Secretion-Excretion

28. 4. Excretion • Purified blood returns to the body through the renal vein, which runs to the Inferior Vena Cava • Urine moves from the nephrons to ureters and goes to the bladder for storage • Once urine is ready to leave the body, the urine will be expelled through the urethra. • Stretch receptors in bladder

29. Recap: http://www.as.miami.edu/chemistry/2086/chap26/chapter%2026-new_part1.htm

30. http://www.ask.com/wiki/Proximal_convoluted_tubule

31. http://www.colorado.edu/intphys/iphy3410saul/outlines08fall/nephron.gifhttp://www.colorado.edu/intphys/iphy3410saul/outlines08fall/nephron.gif

33. Kidney Failure • You have two kidneys in the body located on either side of the spine and extend a little below the ribs. • Your kidneys are bean-shaped organs and is about the size of a fist. • The kidneys receive approximately 10% of the blood that is pumped out of our heart every minute.

34. Your kidneys are responsible for the following: • Regulate fluids • Balance chemicals • Remove wastes • Secrete hormones

35. Condition Explanation: • Progressive in nature • Anemia possible – lack of iron • Malnutrition (lack of appetite) • Decrease well-being • Increased risk for heart disease

36. Toxins build up in blood • Weight gain (excess fluids, swollen ankles, puffiness) • Fluid imbalances – dizziness – nausea

37. Treatment Options: • General • Limit fluid intake, high carb, low protein, low potassium diet • Too much potassium can cause irregular heartbeat

38. Haemodialysis • Most common method • Use of a machine (size of dishwasher) – blood flow through special filter to remove and filter wastes • Clean blood returned to body • Strict schedule – 3 times a week for 3 to 5 hours each time

40. Side effects • Less energy • Loss of time • Once a month blood is tested to see how effective dialysis is – may not work forever!

41. Peritoneal Dialysis • Removes extra water, wastes, and chemicals • Cleansing solution passed through catheter into abdomen • After a couple of hours the solution is drained • Does not require a machine • Strict diet • More recent advances, more flexibility (done at home)

42. Kidney Transplantation • Receive a healthy kidney from a living donor or a recently deceased donor • When effective recovers quality of health AND life • Yields longer life expectancy • Could be long waiting lists (shortage of donors) • Typical Surgery Risks (bleeding, infection, etc.) • Anti-rejection medications after surgery – may weaken immune system • Risk of rejection (body doesn’t accept kidney)