1. The Excretory System
9.5
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2. Excretory System Two main functions:
concentrates wastes & removes them from the body
regulates fluids & water within the body

3. Unicellular Organisms
water balance is often maintained by contractile vacuoles
video of Paramecium
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4. Excretion in Earthworms
hemolymph is taken into metanephridia
ions and waste are reabsorbed & secreted into bladders
excess water & wastes exit through pores
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5. Excretion in Grasshoppers
grasshoppers & other insects use Malphigian tubules to remove uric acid & other wastes
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6. Excretion in Birds
uric acid is excreted through the cloaca (end of digestive tract), along with feces
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7. Human Excretory System
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8. Renal Blood Flow)
blood is brought to the kidneys by the renal arteries
filtered blood leaves the kidneys through the renal veins
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9. The Excretory System
the kidneys remove wastes, balance blood pH, and maintain water balance
they filter the blood plasma
urine (with wastes and toxins) is conducted to the bladder through the ureters

10. Kidney Structure Basic structure: cortex medulla renal pelvis
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11. Kidney Kiwi
Found this website of a medical illustrator on December 6, 2011
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12. Kidney Kiwi Dissection

13. Nephron the functional unit of the kidney is the nephron
about 1 million nephrons in each kidney
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15. Review of Structures…

16. Image from: http://commons. wikimedia

18. Image from :http://kcfac. kilgore. cc. tx

19. (Image from: http://www. medical-illustrations
Afferent Arrives…Efferent Exits

20. How is urine formed?

21. Urine Formation filtration reabsorption secretion
(Image on previous slide from: ,-Sterile.html

22. Filtration higher blood pressure in glomerulus
water, ions, smaller dissolved molecules (glucose, amino acids, urea) move through the walls of the glomerulus
your kidneys filter your entire blood plasma 65 times every day!
glucose, NaCl, H+ ions, amino acids,

23. Reabsorption ion pumps reabsorb Na+, K+, Cl- (active)
active transport proteins reabsorb pretty much all amino acids, glucose & other nutrients
reabsorption of water is by osmosis (passive) and aided by aquaporins
If you produced 120 mL of urine a minute…
(your bladder’s stretch receptors signal to your brain when there is 200mL of urine; can hold up to )
Osmotic gradient created by glucose, amino acids moves water back to blood.

24. Proximal Convoluted Tubule
microvilli increase surface area
ions, gluose, amino acids reabsorbed by passive & active methods
water reabsorbed by osmosis
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25. Loop of Henle water is reabsorbed in the descending portion
ions are reabsorbed in ascending portion (“make medulla salty” as Sal Khan says)
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26. Image: http://droualb. faculty. mjc

27. Distal Tubule & Collecting Duct
reabsorption of ions & secretion of H+ and K+ in distal convoluted tubule
reabsorption of water in collecting duct
some urea reabsorbed (passive) to allow more reabsorption of water

28. Secretion
in the proximal and distal convoluted tubules, and the collecting duct
Blood pH maintained through secretion of H+ ions and reabsorption of HCO3-
detoxified poisons, water-soluble drugs, nitrogen-containing wastes are all secreted

29. Resources
This is a nice detailed animation that goes through the structure of the kidney & the formation of urine:

30. Kidney Disorders

31. Urinalysis
can be used to detect many metabolic and kidney disorders as well as urinary tract infections
urine can be assessed using a dipstick or at a laboratory

32. Multiple Test Dipstick
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33. Diabetes Mellitus Type 1 - body cannot produce insulin
Type 2 - cells fail to use insulin properly
gestational - hormones of pregnancy interfere with action of insulin
urinalysis would show high levels of glucose (and greater volumes of urine)

34. Kidney Stones
caused by precipitation of minerals, can be alkaline or acidic
VERY painful
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35. Kidney Stones - Treatment
time…
lithotripsy (shock-wave therapy)
ureteroscopy (and placement of stent or surgical removal of stone)
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36. Dialysis
for low-functioning kidneys, dialysis machine can filter blood
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37. (Image from: http://www.metrohealth.org/body.cfm?id=1452)