1. Mammalogy (Spring 2015 Althoff)
LEC
10A
• Urinary (Excretory) Systems Overview
Body Fluid Regulation

2. Overview of Excretion External Environment gut lungs kidney skin liver
Blood
TISSUES
CELLS

3. Body Fluid Regulation Keys here: ION & H20 concentrations
Key ions: Na+, Cl-, K+ and HCO3-
Body fluids gain mineral ions from eating foods and drinking fluids
Excretion is the primary way the body loses ions
H20: in via eating foods that contain H20, and drinking H20…and via metabolism (e.g. cellular respiration produces H20 = metabolic water

4. Differences in Osmolarity (i.e., solute concentration
If difference in concentration between two regions, H2O tends to move from regions of greater concentrations to regions of lower concentrations.
Thus H20 moves to regions of highest ION CONCENTRATIONS

5. Fishes & Body Fluid Regulation
FRESHWATER FISH
passive gain of water
across body surface
and through gills
DOES NOT
DRINK
large amounts
of hypotonic urine
contain little salts
salt actively taken
up by gills

6. Fishes & Body Fluid Regulation
DRINKS
SEAWATER
MARINE FISH
passive loss of
water through gills
small amounts of
isotonic urine
Contains
some salts
salt actively excreted
by gills

7. Nitrogenous Waste Products
NITROGENOUS WASTES = breakdown of various molecules, including nucleic acids and amino acids
AMINO ACIDS NOT used for protein synthesis are broken down by the body to generate energy or converted to fats or carbs that can be stored…
…this requires amino groups (-NH2) be removed excreted as ammonia, urea, or uric acid

8. Nitrogenous Wastes PROTEINS amino acids -NH2 Need water to excrete
ammonia
urea
uric acid
Need water to excrete
Need energy to produce

9. Nitrogenous waste Ammonia Urea Uric acid habitat animals toxicity
water
highest
aquatic invertebrates.
bony fishes
amphibian larvae
land
adult amphibians
mammals
2nd
highest
lowest
land
insects
birds
reptiles

10. Maintenance System (1 of 3…digestive & respiratory other 2)
URINARY SYSTEM—kidneys, bladder, & tubes A) rids blood of metabolic wastes B) helps regulate fluid level & chemical content of blood
EXCRETION = rids body of metabolic wastes (remember cellular metabolism) and breakdown of substances that enter the body (non-digestive system).

11. Major role in maintaining HOMESTASIS
Metabolic wastes OUT

12. FUNCTIONS of the Urinary System
Regulate water content of blood
Regulate ion concentrations: Na+, Ca+, K+, Cl-
Regulate pH of blood
Produce erythropoietin  RBC production increases
Eliminate cellular waste such as urea, drugs, etc.

13. Organs of the URINARY System
Kidney (2)
Ureter (1 per kidney)
Urinary bladder
Urethra

14. ORGANS
KIDNEYS – where urine is made
URETERS— muscular tubing carrying urine from kidney to bladder
BLADDER— muscular bag that stores urine until urination (holds ~600 ml)
URETHRA— carries urine out of body

15. URETHRA –some important “minute”
Bladder
infections
Length: cm long, cm long
Passes through prostate gland in (females don’t have) prostate gland contributes fluid to semen that serves as buffer by raising pH of semen to >6.5 to overcome pH environment of vagina
If prostate gland enlarges, it reduces urethrea’s ability to maintain original diameter

16. sphincter “relaxed” at 250 ml
600 ml capacity,
…..internal
sphincter “relaxed”
at 250 ml
INTERNAL SPHINCTER
EXTERNAL SPHINCTER

17. KIDNEY is “the” functional unit of the urinary system

18. Kidney MACROanatomy
Blood supply
Cortex
Medulla
Renal Pelvis

19. Kidney- NEPHRON Functional unit of the kidney 1,000,000 per kidney
Actually produces urine
Transerves the renal cortex and renal medulla
Very detailed structurally speaking

20. Kidney MICROanatomy
Nephron

21. Nephron Detail 4 5 3 2 8 3 1 7 6 Afferent arteriole Efferent arteriole
GLOMERULUS
Glomerular capsule
Proximal convoluted tubule (PCT)
Loop of the Nephron
Distal convoluted tubule (DCT)
Collecting duct 5 3 2 8 3 1 7 6

22. GLOMERULAR
FILTRATION

23. SEM picture
Of a
glomerulus

24. 1 2 NEPHRON CAPSULE Site where, if high blood pressure or injury,
RBC “escape” and
end up in urine 1 2

25. Proximal convoluted tubule (PCT) CROSS-SECTIONAL view
Microvilli (many per cell)

26. URINE FORMATION 3 1 2 4 GLOMERULAR FILTRATION TUBULAR ABSORPTION
TUBULAR SECRETION
And….then there is urine 1 2 4

27. Keep in mind
nephron
transverses
Cortex
AND
medulla
regions of
the kidney

28. Glomerular FILTRATION
Blood is “filtered” (but typically only things dissolved…not formed elements of blood)
Filtrate is one-way….balance of blood moves on through blood vessel
Blood in urine “happens” here….before it gets to the bladder…. BAD!!!!

29. Tubular REABSORPTION
H20 taken out of urine (was part of blood that “filtered out” (60-70%)
NaCl (salts) taken out (think….osmosis process here) (60-70%)
Urine becomes more and more concentrated

30. Tubular SECRETION
Drugs secreted from blood  DCT (distal convulated tubule)
K+, H+, etc. Secreted from blood  DCT (active transport!!!)
NaCl could be reabsorbed here ??? (if low in concentration)
H2O still being taken out of urine, becomes more and more concentrated

31. 1 3
osmosis
active
transport 2
diffusion 4

32. Processes and materials “moved”
Osmosis
Active Transport
H2O
NaCl
Nutrients
SAVED
Diffusion
Urea
NaCl
Drugs K+ H+
NH3
EXCRETED

33. 3 1 2 4 Changes in concentrations of H20, salts, etc. INSIDE & OUTSIDE
the tubules
as urine it flows from
renal cortex to
renal medulla and
back up to renal
cortex…. 3 1 2 4

34. The KING of minimizing H20 loss from the process of urine formation!
KANGAROO RATS (Dipodomys sp.)

35. Controlling pH of the blood…..
CAPILLARY
H++NH3 NH4
KIDNEY
TUBULE
HCO3-
NH4 = ammonium

36. Hormones & the Urinary System
RENIN – promotes retention of NaCl
ANH – (atrial natriuretic hormone) suppresses retention of NaCl
ADH – (antidiuretic hormone) increases H20 taken out of urine
DIRURETICS including alcohol, caffeine drinks: they inhibit ADH, thus not as much reabsorption of H20
Aldosterone– secreted by kidneys promotes K+ secretion.

37. SUMMARY: Urine Formation
Reabsorption
Filtration
Secretion
Glomerulus
Proximal con. tubule
Distal con. tubule
Ureter
Bladder
Urethra
H20 retention is…
decreased
increased
Diuretics
Antidiuretics

38. Kidney Stones