1. The Excretory System

2. Purpose Contributes to homeostasis by helping regulate the volume, electrolyte composition, pH of internal environment and by eliminating metabolic waste products.

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 Main Organs of Excretion 1.) Kidneys These are the main organs of excretion. They are responsible for removing excess water, urea & other excess mineral wastes from the body. The kidneys 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.

5. Three Main Organs of Excretion 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.

6. Three Main Organs of Excretion 3.) Skin: Excretes excess water, salts, and small amounts of urea through sweating.

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

9. How is this different from the excretory system?

10. Structure of Kidney 2 bean shaped kidneys Located on either side of the spinal column, near the lower back Each kidney is about the size of your fist Each are attached to a renal artery & a renal vein

11. Structure of Kidney Each are attached to a renal artery & a renal vein Renal artery carries blood from the heart’s aorta, this blood is unfiltered and full of wastes collected from the whole body!! The renal vein carries blood that has been filtered out of the kidney

12. Structure of Kidney A ureter leaves each kidney with fluid that contains excess water, salts, urea & other waste products Ureters lead to the bladder, where liquid wastes are deposited/stored until released as urine from the body. Expulsion of wastes from bladder is controlled by specific sphincter muscles – voluntary control.

14. Anatomy of a Kidney If you cut a kidney in half you will find 2 distinct regions: 1. Inner Part: Renal Medulla 2. Outer Part: Renal Cortex

15. Anatomy of a Kidney Nephrons  Found in the renal cortex  Working parts of the kidney  Each acts as an individual unit of filtration  About 1 million nephrons per kidney

16. http://www.pitt.edu/~anat/Abdomen/Kidneys/Kidneys.htm

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

18. Nephrons A. Filtration  The nephron begins with Bowman’s Capsule (BC)  BC is a hollow bulb that surrounds a ball of capillaries known as the glomerulus  BLOOD ENTERS BC via the renal artery  Walls of the BC are permeable so blood is filtered through  Filtered materials (urea, glucose, salts, & some vitamins) are called filtrates.

19. Nephrons Filtration Cont’d  Platelets, red and white blood cells are too large to pass, so they remain in the blood  Filtration of blood occurs in the Glomerulus & BC  Adult kidneys filter approx. 180L of blood daily.

20. Nephrons Re-Absorption  Some filtrates are valuable & can’t be lost, so the body reabsorbs them.  Capillaries in the blood reabsorb valuable materials through active transport.  Water returns to blood through osmosis, 99% of the water that is filtered out of BC is reabsorbed into your blood  Takes place in the tubules of the nephron  Excess fluid leaves the BC, enters the tubules and is called URINE.

21. Nephrons Re-absorption Cont’d  First part of tubule is the Proximal Convoluted Tubule (PCT).  The PCT carries fluid down into the Loop of Henle (LH).  Urine is concentrated at the LH.  The urine then moves up the Distal Convoluted Tubule where it eventually meets the ureter

22. Nephrons Re-absorption Cont’d  Purified blood returns to the body through the renal vein, which runs to the Inferior Vena Cava  The urine then moves from the nephrons to the ureters and goes to the bladder where it is stored  Once urine is ready to leave the body, the urine will be expelled through the urethra.

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

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

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

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

28. 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.

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

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

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

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

33. 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

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

36. 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)

37. 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)