1. Excretion AP Biology Ms. Day

2. Waste disposal H OH H N –C– C–OH R CO2 + H2O | | | |
Animals
can’t store
extra
proteins
What waste products?
What do we breakdown?
carbohydrates = CHO  CO2 + H2O (in CR)
lipids = CHO  CO2 + H2O (in CR)
proteins = CHON  CO2 + H2O + N
nucleic acids = CHOPN  CO2 + H2O + P + N
relatively small amount in cell
Can you store sugars? YES
Can you store lipids? YES
Can you store proteins? NO
Animals do not have a protein storage system
=can store H OH H N | | |
CO2 + H2O
–C–
C–OH |
NH2 + H+=
ammonia R

3. Types of Nitrogenous Wastes
Nitrogenous wastes = wastes that contain nitrogen
Toxic by-products of metabolism
Result from breakdown of proteins & nucleic acids
3 Types of wastes
Ammonia (NH3) Excreting it directly is very efficient  no energy expended
Very toxic!!!
Ex: Marine fish
Urea and Uric Acid
Requires energy to convert -NH2 to these forms
Less toxic (uric acid is more toxic than urea b/c not soluble in water)
Ex: Mammals (urea) and Birds (uric acid)

4. VERY TOXIC; very soluble in H2O
produced in liver
VERY TOXIC; very soluble in H2O
LESS TOXIC;
soluble in H2O
TOXIC; Form ppt 
NOT soluble in H20

5. Mammalian Kidneys Bean shaped organs Fist sized
Filters water and solutes such as toxins (except NO proteins…TOO BIG) from blood
Make urine
Helps maintain salt/H2O balance

6. Mammalian Kidney Two regions Renal cortex – outer
Renal medulla – inner
Both regions have nephrons
Nephron
the functional unit of the kidney
Single long tube
Has ball of capillaries called glomerulus
Cup shaped structure at beginning of tube called “Bowman’s capsule”
Surrounds the glomerulus like a funnel

7. Nephron Structure

8. Renal means “kidney”

10. Human Excretory System
Unfiltered blood enters the kidney by the renal artery
Filtered (clean) blood leaves by the renal vein
Urine exits the kidney through a tube called the ureter
Ureters drain into the urinary bladder
Urine exits the bladder through the urethra
Think “a” for away

11. The kidneys, ureters, bladder, and urethra make up the urinary tract.

12. Excretory System in Kidney
Built on a complex network of tubules (TUBES!!!)
Provides a large surface area for the exchange of water and solutes
Including nitrogenous bases (ex: urea)

13. 4 Main Steps in Excretory System1
4 Main Steps in Excretory System 2 3 4

14. 4 Main Processes of Excretory Systems
1. Filtration
Blood goes through filter made of selectively permeable membranes
Keeps proteins and other large molecules
Blood pressure in renal artery forces water/small solutes into kidney
Salts, Sugars, Amino acids, Nitrogenous wastes are filtered into tube/nephron
This makes a liquid called the FILTRATE

15. Occurs in tubes and capillaries
2. Reabsorption
Active transport used
Water and valuable solutes (ex: Ca+2) are moved from filtrate (tubes) back to blood
Required because filtration is not
extremely selective
3. Secretion
Solutes are removed from animal’s body and added to the filtrate
Excess salts & toxins (like urea, drugs)
Urine is drained into the renal pelvis
Renal pelvis collect URINE before ureters get it
4. Excretion
the filtrate (urine) leaves the system
Occurs in tubes and capillaries

16. 1 2 3 4 2 1= filtrate collected here from blood  into nephron
2= Reabsorption into blood occurs (osmosis /active transport)
3= secretion occurs in filtrate
4= urine is collected and dumped into renal pelvis  ureter  excreted into bladder!

18. Animation #4 URINE FORMED!!

19. Summary Not filtered out (remain in blood) Blood cells and proteins
Reabsorbed: active transport
Na+, Cl-, Ca+2 (at times), glucose and amino acids
Reabsorbed: diffusion
Na+ and Cl-
Reabsorbed: osmosis
H2O
Excreted
Urea, H2O, any excess solutes, toxins/drugs

20. Maintaining Water Balance
Monitor blood osmolarity
amount of dissolved material in blood
Acts on collecting duct!!
Drugs and other poisons pass from the peritubular capillaries into the interstitial fluid and then across the epithelium to the nephron’s lumen.
ADH = anti-diuretic hormone

21. Any Questions??

22. http://wps. aw. com/bc_martini_eap_4/40/10469/2680237
x.html
Kidney