1. Anatomy of the Urinary System
Exercise 40
Anatomy of the Urinary System

2. OBJECTIVES Function of urinary system
Location & function of urinary system organs
Blood flow through kidney
Nephron A&P
Glomerular filtration, tubular reabsorption, tubular secretion, micturtion

3. URINARY SYSTEM Excretion of nitrogenous wastes from the body
Maintains electrolyte, acid-base, & fluid homeostasis in the body
Filters & processes the blood:
Removing toxins, metabolic wastes, and excess ions via urine
Retaining needed water, ions, etc. & returning them to blood
Fig 26-1

4. Fig 26-3

5. KIDNEYS Renal capsule: layer (collagen fibers) covering outer surface
Renal cortex: superficial region
Renal medulla: deep region, with triangular structures
Fig 26-4

6. KIDNEYS Renal pyramid: each triangle
Papilla of the pyramids: tip of each pyramid
Renal columns: separate each pyramid
Urine’s produced in pyramid/cortex/ column areas
Fig 26-4

7. KIDNEYS
Calyces:
Minor calyx: cup-shaped drain (collects urine) at each papilla
Major calyx: minors merge into one major
Fig 26-4

8. KIDNEYS Renal pelvis: 2-3 major calyces merge into this region
Fig 26-4

9. KIDNEYS
Fig 26-4

10. KIDNEYS: Blood Vessels
Renal artery: brings oxygenated blood to kidney
Segmental arteries: enters renal pelvis area, 5 branches
Fig 26-5

11. KIDNEYS: Blood Vessels
Lobar artery
Lobar arteries: next branches, near papillae
Interlobar arteries: next branches, in renal columns
Fig 26-5

12. KIDNEYS: Blood Vessels
Lobar artery
Arcuate arteries: next (arching) branches, on top of pyramids
Interlobular arteries: next branches, go into the cortex
Fig 26-5

13. KIDNEYS: Blood Vessels
Afferent arterioles: next branches, leads into capillary networks of nephrons (glomeruli)
Fig 26-5

14. KIDNEYS: Blood Vessels
Glomerulus: capillary bed inside each nephron
Efferent arteriole: leads out of the glomerulus, back into the cortex, will flow into capillaries around tubules 
Fig 26-5

15. KIDNEYS: Blood Vessels
Peritubular capillaries: capillaries around the renal tubules of the nephrons, will drain into venules and go out of kidney (through veins) to renal vein
Fig 26-7

16. Blood flow to/from nephron:
KIDNEYS: Blood Flow
Lobar arteries
Blood flow to/from nephron:
Fig 26-5

17. KIDNEYS: NEPHRONS
Nephron: a functional unit of the kidney, urine is produced here—in the cortex of each renal lobe
Each kidney has ~1.25 million!!
Fig 26-7

18. KIDNEYS: NEPHRONS
Glomerular (Bowman’s) capsule: round, cup-shaped structure enclosing the glomerulus
Fig 26-8

19. Convuluted portions are in the cortex
KIDNEYS: NEPHRONS
Proximal convuluted tubule: 1st segment of renal tubule—absorb organic nutrients, ions, water, plasma proteins from tubular fluid, release to interstitial fluid around the tubule *reabsorption*
Convuluted portions are in the cortex
Fig 26-6

20. Loops extend into the medulla
KIDNEYS: NEPHRONS
Descending limb of Loop of Henle: 2nd segment of renal tubule—more reabsorption of water
Ascending limb of Loop of Henle: 3rd segment—more reabsorption-Na+, Cl-
Loops extend into the medulla
Fig 26-6

21. Convuluted portions are in the cortex
KIDNEYS: NEPHRONS
Distal convuluted tubule: 4th segment of renal tubule—secretion of ions, acids, drugs, toxins; some reabsorption (water, Na+, Ca++)
Convuluted portions are in the cortex
Fig 26-6

22. KIDNEYS: NEPHRONS
Distal convuluted tubule actually wraps around the glomerulus
Fig 26-7

23. KIDNEYS: NEPHRONS
Collecting tubule: Final segment of renal tubule—some secretion of ions (Na+, K+, H+, HCO3-), & some reabsorption of water
Fig 26-6

24. KIDNEYS: NEPHRONS
Juxtaglomerular apparatus: endocrine region of each nephron, important in filtrate formation—secretes the hormone erythropoietin & the enzyme renin
Fig

25. KIDNEYS: Juxtaglomerular apparatus
Made up of:
MACULA DENSA CELLS: Epithelial cells of distal convoluted tubule NEAR glomerulus (are taller than the rest along DCT, & nuclei are clustered together)
JUXTAGLOMERULAR CELLS: smooth muscle fibers in the afferent arteriole walls

26. KIDNEYS: Juxtaglomerular apparatus
Fig 26-8

27. Glomerular Filtration
Passive transport (filtration)
Blood (filtrate) passes from glomerulus (capillaries) to glomerular capsule
Then enters proximal convoluted tubule
Fig. 26-9

28. Tubular Reabsorption Mostly in proximal convoluted tubule
Components of filtrate move through tubule cells & return to blood (peritubular capillaries)
Passive (osmosis) or active (highly selective/specific) transport, depending on body’s needs and blood’s composition at that time
Water, glucose, amino acids, ions, some waste products (urea)
Fig. 26-9

29. Tubular Secretion Reverse of Absorption
Mostly in distal conv tubule & collecting ducts
Components of blood move from peritubular capillaries or tubular cells INTO the tubule’s filtrate—to be excreted in urine
Active transport
H+, K+, creatinine, drug metabolites
Fig. 26-9

30. Urine Flow
From collecting duct of renal tubule goes to minor calyx, to major calyx, to renal pelvis, to
URETER: (1 for each kidney) drains urine from kidney to urinary bladder
Fig 26-8

31. BLADDER
Trigone: triangular region near uteral openings and entrance to the urethra
Fig 26-19

32. Internal urethral sphincter: smooth muscle surrounding the opening from bladder to urethra—involuntary control
Fig 26-19

33. External urethral sphincter: skeletal muscle surrounding the opening from urethra to outside—voluntary control (has resting muscle tone, must be voluntarily relaxed)
Fig 26-19

34. Micturition
Process of urination
There is a micturition reflex
Urine moves through ureters to bladder by peristaltic contraction
Bladder fills with urine, stimulates stretch receptors in bladder wall
Afferent fibersspinal cord, brainbecome aware of fluid pressure in your bladder
Efferent fibers stimulate detrusor muscle (walls of bladder), which elevates fluid pressure
If internal (involuntary) and external (voluntary) urethral sphincters BOTH relax urination
If pressure builds too high, it can force the internal sphincter to open, which leads to reflexive relaxation of external sphincter

35. Bladder Location
MALE FEMALE
Fig