1. Excretion CO2, H2O H2O mineral salts
The removal of cellular waste products.
The metabolic activities of living organisms produce wastes.
metabolic activity waste
respiration
dehydration synthesis
protein* metabolism
other metabolic
activities
CO2, H2O
H2O
nitrogenous wastes
*proteins contain
nitrogen!
mineral salts

2. Proteins are composed of repeating units called _________________
amino acids
Proteins are composed of repeating units called _________________
Amino acids contain the element Nitrogen: O H H
C C N
OH R H
When these amino acids are broken down (hydrolyzed), nitogenous wastes are produced . This process is called _____________________
deamination
Nitrogenous wastes vary from the extremely toxic to nontoxic as follows:
extremely toxic
less toxic
nontoxic
ammonia
urea
uric acid

3. Adaptations for Excretion
1. Protists (ameba, paramecium)
CO2 & H2O diffuse across the cell membrane
excess H2O pumped out by contractile vacuole
2. Algae
CO2 from respiration is recycled/reused for photosynthesis

4. See “Awesome Adaptations” sheet
3. Plants
recycle CO2 & O2 for photosynthesis and respiration
excess gases leave stomates and lenticels
toxic wastes are stored in vacuoles ( can be harmful to
organisms that eat the plant)…go to
See “Awesome Adaptations” sheet

5. Human Excretion excretion vs. egestion
removal of metabolic wastes (CO2, H2O, salts & nitrogenous wastes: ammonia, urea, uric acid)
removal of undigested or indigestible material (fiber, corn, penny)

6. lungs
liver
kidney
4. skin

7. Organs of Excretion 1. Lungs-
CO2 & H2O from aerobic respiration are removed when you exhale
2. Liver-
“clearing house” of the body
largest organ in the body
breaks down dead and worn out RBCs
hemoglobin found in RBC broken down to urochrome (yellow):the pigment in bile
if bile isn’t eliminated properly, the skin becomes jaundice (yellow)
bile …
~stored in gall bladder
~aids in the emulsification of fat
~contains salts, cholesterol & urochrome
~eliminated with feces

8. The liver also disposes of nitrogenous wastes by making urea :
sweat
Proteins amino
acids
travels
through
deamination
urea
blood
urine
Deamination…breaks down an amino acid and removes the NH2 group : O H H
C C N
OH R H
The remaining C,H and O are avaialable now to be reassembled into products that are useful to the body (very efficient!)

9. Ex). pyruvic acid- can enter the respiration pathway &
produce energy
glycogen- form of stored energy in animals
fats- can be stored for energy
The liver also detoxifies (makes harmless) substances such as alcohol

10. skin-
contains sweat glands (coiled tubes in dermis) that have ducts leading to pores in the epidermis
capillaries surround sweat glands: H2O, salts & urea
diffuse from blood gland to form sweat
sweat regulates body T0/homeostasis when sweat
evaporates and cools the skin

12. 4. Urinary system
consists of:
1. kidneys-
filter waste from blood, produce urine
2. ureters-
carry urine from kidney to bladder
3. urinary bladder-
stores urine
4. urethra-
carries urine from bladder out of body

13. B. Structure of the kidney
1. cortex-
outer region, blood is filtered, has nephrons
2. medulla-
middle, has collecting tubules & nephrons
3. pelvis-
inner, connected to the ureter
C. Nephron: the functional unit of the kidney
1. microscopic filtering units
2. about 1 million/kidney (increased surface area for
filtration)
3. located in the cortex and medulla

14. cortex medulla pelvis ureter renal artery renal vein adrenal gland
kidney
ureter
pelvis
bladder
ureter
urethra

15. D. Formation of Urine
occurs in the nephrons
consists of 2 stages:
filtration (of the blood)
reabsorption (when the blood
reabsorbs the materials it needs)
FILTRATION
a. blood enters the glomerulus (bed of capillaries)
b. substances under pressure move into the Bowman’s capsule
c. this is called filtrate and contains:
water glucose
salts amino acids
urea

16. reabsorbed collected as urine
Bowman’s capsule
renal arteriole
renal artery
glomerulus
capillary
collecting tubule
renal vein
renal venule
Loop of Henle
good stuff waste
reabsorbed collected as
urine

17. Note: blood cells and large molecules like proteins are too large to pass into Bowman’s capsule.
If they detect blood or protein in your urine, there’s a problem!
Approx. 180 L filtrate/day produced but only 1 to 1.5L urine/day b/c …….
your kidneys reabsorb most of the filtrate to maintain water, salt and nutrient levels in your body.
REABSORPTION
a. Filtrate moves through the Loop of Henle
Most water, some salts & all glucose and amino acids are
reabsorbed (returned to the blood) by the capillaries
that surround the Loop of Henle.
~water diffuses
~other substances may require active transport

18. c. The fluid remaining in the tubule is called urine (water,
salts, urea)
d. Urine passes to the collecting duct ureter bladder
Kidney threshold level
~most substances have a threshold level in the blood
~ if the blood concentration of a substance exceeds this level, the excess is NOT reabsorbed, but it is excreted
ex) sugar found in the urine of a diabetic
nephron clip\\Shsshared\SHSSHARED\Science Dept L\biomovies\nephron.mov
Diuretic drugs-
Medications that decrease the amount of fluid/water in your body by INCREASING FILTRATION AND DECREASING REABSORPTION (of the fluid/water)
An increase in fluid may be caused by (and a cause of) congestive heart failure, liver disease, kidney disease

19. Disruption sheet

20. Functional unit analogy
alveoli :: lungs
villi :: small intestine
:: kidney
nephron

22. /loop of Henle
blood vessels