1. The Urinary System

2. Functions Excretion of aqueous wastes Monitor and regulate:
Fluid balance
Blood volume
Blood pressure
Red blood cell levels
Blood chemistry
Vitamin D synthesis

3. Four Organs of Urinary System

4. Placement of Kidneys
Kidneys are retroperitoneal

5. Internal Anatomy of the Kidney
Filtration occurs in the cortex
Medulla fine-tunes filtrate into urine

6. Kidney Blood Flow

7. Kidney Blood Flow

8. Your body takes nutrients from food and uses them to maintain all bodily functions including energy and self-repair. After your body has taken what it needs from the food, waste products are left behind in the blood and in the bowel. The urinary system works with the lungs, skin, and intestines—all of which also excrete wastes—to keep the chemicals and water in your body balanced.

9. Adults eliminate about a quart and a half of urine each day
Adults eliminate about a quart and a half of urine each day. The amount depends on many factors, especially the amounts of fluid and food a person consumes and how much fluid is lost through sweat and breathing. Certain types of medications can also affect the amount of urine eliminated.

10. Kidneys
The kidneys remove urea from the blood through tiny filtering units called nephrons.
Each nephron consists of a ball formed of small blood capillaries, called a glomerulus, and a small tube called a renal tubule.
Urea, together with water and other waste substances, forms the urine as it passes through the nephrons and down the renal tubules of the kidney.

11. Ureters
From the kidneys, urine travels down two thin tubes called ureters to the bladder.
The ureters are about 8 to 10 inches long. Muscles in the ureter walls constantly tighten and relax to force urine downward away from the kidneys.
If urine is allowed to stand still, or back up, a kidney infection can develop. Small amounts of urine are emptied into the bladder from the ureters about every 10 to 15 seconds.

12. Bladder
The bladder is a hollow muscular organ shaped like a balloon. It sits in your pelvis and is held in place by ligaments attached to other organs and the pelvic bones. The bladder stores urine until you are ready to go to the bathroom to empty it. It swells into a round shape when it is full and gets smaller when empty.

13. Sphincter
Circular muscles called sphincters help keep urine from leaking. The sphincter muscles close tightly like a rubber band around the opening of the bladder into the urethra, the tube that allows urine to pass outside the body.

14. Nerves in the bladder
Nerves in the bladder tell you when it is time to urinate, or empty your bladder.
As the bladder first fills with urine, you may notice a feeling that you need to urinate.
The sensation to urinate becomes stronger as the bladder continues to fill and reaches its limit.
At that point, nerves from the bladder send a message to the brain that the bladder is full, and your urge to empty your bladder intensifies.

15. Nephron Anatomy
Millions of these units accomplish the filtering of blood

16. Glomerular Pressure
What consequences would a drop in blood pressure produce here?

17. Renal Corpuscle Histology
Filtration occurs here through fenestrations
Formed elements and plasma proteins remain

18. Proximal Convoluted Tubule
What feature facilitates the reabsorption of important solutes?

19. Distal Convoluted Tubule
Secretion of larger unwanted substances
Final fine-tuning of blood in peritubular capillaries

20. Nephron Loop
Countercurrent multiplication produces a very salty medulla
Descending limb permeable to water, ascending limb is not

21. Urine Formation Summary

22. Ureters
Carry urine from renal pelvis to urinary bladder

23. Urinary Bladder Transitional epithelium allows this organ to stretch
Mucus protects lining from toxic substances in urine

24. Urethra
Compare the male and female urethra.

25. Urethra
Compare the male and female urethra.

26. Dilute Urine Formation
Brown and blue line indicate impermeability to water in specific regions

27. Concentrated Urine Formation
Salty medulla and ADH create the conditions for producing concentrated urine

28. Antidiuretic Hormone and Homeostasis
Acts to preserve volume of water in body at healthy level
Increases permeability to water at end of nephron

29. Other Factors Aldosterone
Excretion of K+ and reabsorption of Na+
Atrial natriuretic peptide, brain natriuretic peptide
Oppose ADH
Caffeine and alcohol
Decreases ADH production

30. Bicarbonate Buffer System
H+ + HCO3-  H2CO3  H2O + CO2
As indicated by the arrows, this chemical reaction can proceed in either direction
For example, increasing CO2 will drive the reaction to the left
Increases acidity

31. Respiratory Regulation of Blood pH

32. Urinary Regulation of Blood pH
Kidneys can adjust excretion of H+ and HCO3- according to the need

33. Urinary Regulation of Blood pH
Kidneys can adjust excretion of H+ and HCO3- according to the need

34. Urinalysis

35. Urinalysis

36. Urinary Disorders
Benign prostatic hyperplasia (BPH) is a condition in men that affects the prostate gland, which is part of the male reproductive system. BPH is an enlargement of the prostate gland that can interfere with urinary function in older men.
It causes blockage by squeezing the urethra, which can make it difficult to urinate. Most men over age 60 have some BPH, but not all have problems with blockage. There are many different treatment options for BPH.

37. Urinary Disorders
Kidney stones is the term commonly used to refer to stones, or calculi, in the urinary system. Stones form in the kidneys and may be found anywhere in the urinary system. They vary in size. Some stones cause great pain while others cause very little. The aim of treatment is to remove the stones, prevent infection, and prevent recurrence. Both nonsurgical and surgical treatments are used. Kidney stones affect men more often than women.

38. Kidney Stones As water is absorbed, stones can form
Jagged edges are painful
Larger stones can be broken by ultrasound

39. Kidney Diseases Failing kidneys require help
Dialysis artificially mimics the kidneys by diffusion across a membrane
Hemodialysis
Blood is withdrawn and passed across a dialysis membrane
A carefully prepared solution will prevent necessary components from being lost and force the diffusion of wastes
Peritoneal dialysis
Dialysis fluid is put directly into abdominal cavity and left to diffuse

40. Urinary Disorders
Renal (kidney) failure results when the kidneys are not able to regulate water and chemicals in the body or remove waste products from your blood. Acute renal failure (ARF) is the sudden onset of kidney failure. This condition can be caused by an accident that injures the kidneys, loss of a lot of blood, or some drugs or poisons.
Can be saved if caught in time

41. Urinary Disorders
Urinary tract infections (UTIs) are caused by bacteria in the urinary tract. Women get UTIs more often than men. UTIs are treated with antibiotics. Drinking lots of fluids also helps by flushing out the bacteria.
The name of the UTI depends on its location in the urinary tract. An infection in the bladder is called cystitis. If the infection is in one or both of the kidneys, the infection is called pyelonephritis. This type of UTI can cause serious damage to the kidneys if it is not adequately treated.

42. Summary of Main Points
The urinary system is composed of the kidneys and their nephrons, ureters, urinary bladder and urethra
Urine formation is accomplished by:
Filtration
Reabsorption
Secretion
Maintains:
Water-salt balance
Acid-base balance
Dialysis can mimic the kidney function