1. A&P II URINARY SYSTEM

2. Urinary Anatomy Kidney Ureter Bladder Urethra
The urinary system consists of two kidneys that filter the blood, two ureters, a urinary bladder, and a urethra to convey waste substances to the outside
Kidney
Ureter
Bladder
Urethra

3. Functions of Urinary System
The kidneys are positioned retroperitoneally on either side of the vertebral column between the twelfth thoracic and third lumbar vertebrae
Clears blood of waste products of metabolism
Uremia
accumulation of toxic levels of wastes in blood
maintain normal
H2O and electrolyte balance
fluid volumes
blood pressure
body pH

4. Kidneys Excretory Organ Excretes Intestine, Skin, Lungs N2 wastes
Toxins
H20
Electrolytes

5. Kidney
Kidney Functions
The kidneys function to regulate the volume, composition, and pH of body fluids and remove metabolic wastes from the blood in the process.
The kidneys also help control the rate of red blood cell formation by secreting erythropoietin, and regulate blood pressure by secreting renin.

6. Microscopic Structure
Nephron
unit of function
1.25 million / kidney
Highly vascular
20% of blood pumped / min

7. Functions 1) maintain fluid balance 2) maintain electrolyte balance
3) maintain acid-base balance
4) remove N2 wastes
urea
5) synthesize prostaglandin's
6) influence rate of secretion of hormones
ADH / Aldosterone

8. Nephron Anatomy 1) Glomerulus 2) Tubule Arterioles Bowman’s Capsule
Proximal
Loop of Henle
Ascending
Descending
Distal
Collecting

9. Urine Formation Actions in forming urine 1) filtration 2) reabsorption
3) secretion

10. Fluid is squeezed out of the glomerular capillary bed
Resorption
Most nutrients, water ad essential ions are returned to the blood of the peritubular capillaries
Secretion
c. Moves additional undesirable molecules into tubule from blood of peritubular capillaries

11. Glomerular Filtration
blood flows through glomerular capillaries
H2O and solutes filter out into Bowman’s Capsule

12. Glomerular Filtration
blood flows through glomerular capillaries
H2O and solutes filter out into Bowman’s Capsule

13. Glomerular Filtration
pressure gradient causes filtration
some kidney diseases
permeability of glomerulus increases
allows blood proteins to filter out into the capsule

14. Glomerular Filtration
High blood pressure in the glomerulus forces small molecules from blood into the Bowman’s capsule

15. Glomerular Filtration
Stress can lead to constriction of afferent arterioles
causes filtration rate to lower
and renal suppression “kidney shutdown”

16. Glomerular Filtration
glomerular filtration rate directly related to systemic blood pressure
↓ BP = ↓ glomerular filtration
↑ BP = ↑ glomerular filtration (slight)

17. Tubular Reabsorption
Glucose, amino acids, ions and other useful substances are actively transported from the tubule into blood

18. Glucose Reabsorption
if blood glucose levels exceed threshold amount (150mg/100ml)
not all glucose is reabsorbed

19. Reabsorption from Loop of Henle
Descending Loop
Water diffuses out of the tubule by osmosis

20. Reabsorption from Loop of Henle
Ascending Loop
Salts are actively transported out of the tubule, but water cannot follow because the walls of the tubule are impermeable to water

21. Reabsorption from Loop of Henle
NaCl is trapped in interstitial fluid of kidney medulla

22. Reabsorption from Distal Tubules
proximal tubules reabsorb 2/3 of Na+
distal tubules reabsorb 1/10 of Na+

23. Reabsorption from Distal Tubules
distal tubules reabsorb H2O if antidiuretic hormone (ADH) is present

24. Distal Tubule
K+, H+ and other ions, and certain large molecules are actively transported from the blood into the tubule, regulating the pH and ionic concentration of the blood

25. Collecting Duct
As the urine passes down the duct, water moves by osmosis from the duct into the blood

26. Collecting Duct
As the urine passes down the duct, water moves by osmosis from the duct into the blood

27. ADH
cause distal tubules to become permeable to H2O

28. Regulation of Urine Volume
1) ADH
2) Aldosterone
3) Extracellular fluid volume
4) Urine solute concentration

29. Regulation of Urine Volume
1) ADH
Presence
decrease Urine Volume
Absence
increase Urine Volume

30. Regulation of Urine Volume
2) Aldosterone
increases Na+ reabsorption in distal tubule with H2O following

31. Regulation of Urine Volume
3) urine volume relates directly to extracellular fluid volume (ECF)
ECF ↓ urine volume ↓
ECF ↑ urine volume ↑
rapid ingestion of large amount of fluid and resulting increased ECF leads to increased urinary output

32. Regulation of Urine Volume
4) high solute concentration in urine increases urine volume by osmotic pressure
untreated diabetes
void large amounts of urine because excess glucose in blood “spilling over”

33. Influence of Kidney on Blood Pressure
Renal Hypertension
decreased blood flow to kidney
constriction of arterioles
increased BP

34. Ureters Tubes leading from kidney to bladder
Urine moves by peristaltic movement

35. Ureters Renal Calculi distend ureter walls
stones develop in kidney, washed out by urine into ureter
distend ureter walls
pain

36. Bladder
collapsible, elastic bag
Ureters 2
Bladder
Urethra 1

37. Functions of Bladder 1) reservoir for urine 2) expels urine
distended causes sensation and desire to void

38. Urethra
passageway for eliminating urine

39. Urethra passageway for eliminating urine
Smooth muscle with inner mucosa changes from transitional through stages to stratified squamous near end
Drains urine out of the bladder and body
Male: about 20 cm (8”) long
Female: 3-4 cm (1.5”) long
Short length is why females have more urinary tract infections than males - ascending bacteria from stool contamination

40. Urine
H2O
95%
N2 wastes
Electrolytes
Toxins
Pigments
Hormones