1. Osmoregulation and Excretion
Chapter 44.1 to 44.4
Osmoregulation and Excretion

2. Selectively permeable membrane
Fig Fill in the missing information.
Selectively permeable
membrane
_________
Net water flow
_________
Figure 44.2 Solute concentration and osmosis
______________ side
__________________ side

3. Excretion of salt ions and small amounts of water in
Fig. 44-4a Are saltwater fish losing or gaining water from its environment? Is there urine dilute or concentrated?
Gain of water and
salt ions from food
Excretion
of salt ions
from gills
Osmotic water
loss through gills
and other parts
of body surface
Figure 44.4a Osmoregulation in marine and freshwater bony fishes: a comparison
Gain of water
and salt ions from
drinking seawater
Excretion of salt ions and
small amounts of water in
scanty urine from kidneys
(a) Osmoregulation in a saltwater fish

4. Uptake of salt ions by gills
Fig. 44-4b Are freshwater fish losing or gaining water from its environment? Is there urine dilute or concentrated?
Uptake of water and
some ions in food
Osmotic water
gain through gills
and other parts
of body surface
Uptake of salt ions by gills
Figure 44.4b Osmoregulation in marine and freshwater bony fishes: a comparison
Excretion of large
amounts of water in
dilute urine from kidneys
(b) Osmoregulation in a freshwater fish

5. (a) Hydrated tardigrade (b) Dehydrated tardigrade
Fig How have these organisms evolved to survive with little water?
100 µm
100 µm
Figure 44.5 Anhydrobiosis
(a) Hydrated tardigrade
(b) Dehydrated
tardigrade

6. Water balance in a kangaroo rat (2 mL/day) Water balance in a human
Fig. 44-6a If both animals are mammals, why don’t they use the same method to obtain water?
Water
balance in a
kangaroo rat
(2 mL/day)
Water
balance in
a human
(2,500 mL/day)
Ingested
in food (0.2)
Ingested
in food (750)
Ingested
in liquid (1,500)
Water
gain
(mL)
Figure 44.6 Water balance in two terrestrial mammals
Derived from
metabolism (1.8)
Derived from
metabolism (250)

7. EXPERIMENT Nasal salt gland Nostril with salt secretions Ducts
Fig How would the type of animal prey that a marine bird eats influence how much salt it needs to eliminate?
EXPERIMENT
Nasal salt
gland
Ducts
Nostril
with salt
secretions
Figure 44.7 How do seabirds eliminate excess salt from their bodies?

8. Proteins Nucleic acids Amino acids Nitrogenous bases Amino groups
Fig Where does the amino group
that is eliminated as waste
product come from? How does the
environment affect the form in which
the amino group is eliminated?
Proteins
Nucleic acids
Amino
acids
Nitrogenous
bases
Amino groups
Most aquatic
animals, including
most bony fishes
Mammals, most
amphibians, sharks,
some bony fishes
Many reptiles
(including birds),
insects, land snails
Figure 44.9 Nitrogenous wastes
Ammonia
Urea
Uric acid

9. Filtration Capillary Excretory tubule
Fig Match the statements with the functions in the diagram.
Secretion: Toxins and excess ions are pulled from the blood to the filtrate.
Filtration: Initial step of altering blood composition by moving water and solutes through Bowman’s capsule.
Excretion: When the final filtrate called urine leaves exits.
Reabsorption: The filtrate is adjusted by pulling out valuable substrates and returning them back into the body fluids.
Filtration
Capillary
Filtrate
Excretory
tubule
Figure Key functions of excretory systems: an overview
Urine

10. (a) Excretory organs and major associated blood vessels
Fig a What supplies blood to the kidneys? Drains blood away from the kidneys?
vena cava
Renal artery
and vein
Kidney
Aorta
Ureter
Figure 44.14a The mammalian excretory system
Urinary
bladder
Urethra
(a) Excretory organs and major
associated blood vessels

11. Renal medulla Renal cortex Renal pelvis Ureter Section of kidney
Fig b Where does fluid from the renal medulla initially collect? Where does all of that fluid collect?
Renal
medulla
Renal
cortex
Renal
pelvis
Figure 44.14b The mammalian excretory system
Ureter
Section of kidney
from a rat
(b) Kidney structure
4 mm

12. 10 µm Bowman’s capsule Glomerulus SEM Proximal tubule Distal tubule
Fig d What pattern can be seen in how the pathway of oxygenated and deoxygenated blood is laid out?
10 µm
Glomerulus
Bowman’s capsule
SEM
Proximal tubule
Distal
tubule
Collecting
duct
Descending
limb
Figure 44.14d The mammalian excretory system
Loop of
Henle
Ascending
limb
Vasa
recta
(d) Filtrate and blood flow

13. Proximal tubule Distal tubule Filtrate CORTEX Loop of Henle OUTER
Fig Some cells lining tubules in the kidney synthesize organic solutes to maintain normal cell volume. Where in the kidney would you find these cells? Explain.
Proximal tubule
Distal tubule
NaCl
Nutrients
H2O
HCO3–
H2O K+
NaCl
HCO3– H+
NH3 K+ H+
Filtrate
CORTEX
Loop of
Henle
NaCl
H2O
OUTER
MEDULLA
NaCl
NaCl
Collecting
duct
Figure The nephron and collecting duct: regional functions of the transport epithelium
Key
Urea
Active
transport
NaCl
H2O
Passive
transport
INNER
MEDULLA

14. Fig The drug furosemide blocks the contransporters for Na+ and Cl- in the ascending limb of the loop of Henle. What effect would you expect this drug to have on urine volume?
Osmolarity of
interstitial
fluid
(mOsm/L)
300
300
300
100
100
300
300
H2O
NaCl
H2O
CORTEX
400
200
400
400
H2O
NaCl
H2O
NaCl
H2O
NaCl
H2O
NaCl
H2O
NaCl
H2O
OUTER
MEDULLA
600
400
600
600
Figure How the human kidney concentrates urine: the two-solute model
H2O
NaCl
H2O
Urea
H2O
NaCl
H2O
900
700
900
Key
Urea
H2O
NaCl
H2O
Active
transport
INNER
MEDULLA
Urea
1,200
1,200
Passive
transport
1,200

15. Fig. 44-17 What is the advantage of excreting waste as uric acid like this roadrunner does?
Figure The roadrunner (Geococcyx californianus), an animal well adapted for conserving water