The Urinary System

1. The Urinary System

2. Primary Functions of the Urinary System Excretion -The removal of organic waste products from body fluids Elimination -The discharge of excess water and waste products Homeostatic regulation of blood -Regulating blood volume and pressure -Regulating plasma ion concentrations -Stabilizing blood pH

3. Urinary System Organs

4. Urinary System Organs: the Kidneys • About the size of your fist, the kidneys are bean shaped organs located in the posterior abdominal cavity.

5. Urinary System Organs: the Kidneys cont. • the kidneys' main role is to filter water soluble waste products from the blood, and to regulate the water volume in the blood.

7. The Kidney • Blood enters each kidney through the renal artery and branches into arterioles and capillaries which encompass the medulla.

8. The Kidney cont. • Capillaries then come into contact with the functional unit within the kidney called the nephron. • A healthy kidney has over one million functional nephrons

9. The Nephron at a Glance…

11. The Kidney cont. • The filtering unit within the nephron is called the glomerulus. High pressure results in the It removal of water and solutes from the blood , which collect in the Bowman’s Capsule.

12. The Kidney cont. • The filtrate (excess water and solutes) then pass through tubules. • The tubules are lined with specially designed cells which process the filtrate, allowing the reabsorbtionof water and chemicals useful to the body, while passing on excess water and waste products.

13. Reabsorbtion and ADH The Renin-Angiotensin-Alderosterone System is a hormone system that regulates blood pressure and fluid balance… Via both active and passive transport, specialized cells which line the proximal/distal tubules respond to ADH (from the pituitary) and aldosterone (from the adrenal glands) effectively regulating the re-uptake of water, conservation of Na+ ions, and secretion of K+ ions. This re-absorption capacity is essential in homeostatic regulation of the blood.

14. Angiotensinogenis generated by the liver and becomes Angiotensinwhen activated by Renin secretion (from the juxtaglomerularapparatus within the kidneys). These hormones ellicit a cascade of responses among multiple body systems to maintain homeostasis. Can you trace these pathways?....

17. Did you know? kangaroo rats produce the most concentrated urine of all mammals, and only pass a few drops per day. the extended Loop of Henle, which enables the enhanced concentration process.

18. Collecting Waste Material • The excess filtrate leads to the renal pelvisvia collecting ducts and eventually to the ureter. • What is “filtrate” referred to as at this point?

19. The Kidney cont. • Filtered “clean” blood (now blue) re-collects and returns to the heart via the renal vein. What are the structures labeled at X and Y?

20. Did you know… • The kidneys take in and process 1.25 liters of blood per minute. That’s 25% of your total blood volume!

21. Filtrate = Urine • Urine is composed primarily of water, but also contains: -Urea/Uric Acid-Bi-product of protein metabolism -Dissolved Materials-Sodium, Chloride, potassium, bicarbonate, hydrogen Ions, and various other water soluable components.

22. Did you Know?... Biliruben, the chemical that makes urine yellow, is generated in the liver. The color of your urine is a key hydration indicator. Normal Hydration dehydration

23. The Ureters • Urine collects in the renal pelvis and drains through long muscular tubes called ureters to the bladder.

24. The Bladder • The urinary bladder is a hollow muscular pouch that sits on the floor of the pelvis. Urine enters the bladder via the ureters and exits via the urethra.

25. Did You Know? The world famous astronomer Tycho Brahe died of a complication to his bladder, when he did not urinate from politeness at a dinner in Prague 1601, eleven days before his death.

27. The Urethral Sphincter urethral sphincter muscles are used to control the flow of urine, or micturition from the urinary bladder. These muscles surround the urethra, effectivley sealing the urethra shut until relaxed.

28. Did you Know…. Males have a 2nd urethral sphincter at the base of the prostate gland (it prevents reflux of seminal fluids into the bladder during ejaculation) which is not present in females. Females typically must urinate more often than males due to the bladder sharing space with reproductive organs.

29. Challenge Question • How much urine can your bladder hold?

30. Kidney Disease Sometime genetic and/or environmental factors can lead to a decline in kidney function over time. When this happens one must undergo regular dialysis sessions, in which a machine (a hemodialyzer) substitutes for regular kidney function.

31. Kidney Stones Mineral crystals can sometimes form in the renal pelvis and are usually passed without notice, however, if they get large enough, they’re referred to as kidney stones. Passing a kidney stone is remarkably painful!

32. The Urethra • the urethra is a tube which connects the urinary bladder to the outside of the body. In males, the urethra acts as a passage for semen and urine.

33. H Pop Quiz! I O N G M J L K Identify structures A-R Q P R

34. “That’s All Folks!” More to come…