Transcript The Excretory System - Cal State LA

BIOL 100C:
Introductory Biology III
The Excretory System
Dr. P. Narguizian
Fall 2012
Principles of Biology
Education-Portal: Online Video
• Excretory System
• http://education-portal.com/academy/lesson/excretorysystem.html
OSMOREGULATION
AND EXCRETION
•
Animals balance the gain and loss of water
and solutes through osmoregulation
 Osmoconformers
– Have the same internal solute concentration as
seawater
– Many marine invertebrates are osmoconformers
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Animals balance the gain and loss of water and
solutes through osmoregulation
 Osmoregulators control their solute
concentrations
 Freshwater fishes
– Gain water by osmosis
– Excrete excess water
– Pump salt across their gills
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Osmotic water gain through gills
and other parts of body surface
Uptake of
some ions
in food
Uptake of
salt by
gills
Excretion of
large amounts of
water in dilute
urine from kidneys
Animals balance the gain and loss of water and
solutes through osmoregulation
 Saltwater fish
– Lose water by osmosis
– Drink seawater
– Pump out excess salt
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Gain of water and
salt from food
and by drinking
seawater
Excretion of salt
from gills
Osmotic water loss
through gills and other
parts of body surface
Excretion of excess
ions and small
amounts of water
in scanty urine
from kidneys
Animals balance the gain and loss of water and
solutes through osmoregulation
 Land animals
– Gain water by drinking and eating
– Lose water by evaporation and waste disposal
– Conserve water using
– Kidneys
– Behavior adaptations
– Waterproof skin
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EVOLUTION CONNECTION: A variety of
ways to dispose of nitrogenous wastes have
evolved in animals
 Nitrogenous wastes are toxic breakdown products
of protein
 Animals dispose of nitrogenous wastes in different
ways
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EVOLUTION CONNECTION: A variety of
ways to dispose of nitrogenous wastes have
evolved in animals
 Ammonia (NH3)
– Poisonous
– Soluble in water
– Easily disposed of by aquatic animals
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EVOLUTION CONNECTION: A variety of
ways to dispose of nitrogenous wastes have
evolved in animals
 Urea
– Less toxic
– Easier to store
– Some land animals save water by excreting uric acid
– A virtually dry waste
– Urea and uric acid take energy to produce
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Proteins
Nitrogenous bases
Amino acids
Nucleic acids
—NH2
Amino groups
Most aquatic animals,
including most fishes
Ammonia
Mammals, amphibians, Birds and many other
sharks, some bony
reptiles, insects, land
fishes
snails
Urea
Uric acid
The urinary system plays several major roles in
homeostasis
 The excretory system
– Expels wastes
– Regulates water balance
– Regulates ion balance
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The urinary system plays several major roles in
homeostasis
 Nephrons
– Functional units of the kidneys
– Extract a filtrate from the blood
– Refine the filtrate to produce urine
 Urine
– Ureters drain the kidneys
– Stored in the urinary bladder
– Expelled through the urethra
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Aorta
Inferior
vena cava
Renal artery and vein
Kidney
Ureter
Urinary bladder
Urethra
Renal cortex
Renal medulla
Renal pelvis
Ureter
Bowman’s
capsule
Tubule
Renal cortex
Renal artery
Renal vein
Collecting
duct
Renal medulla
To
renal
pelvis
Bowman’s
capsule
Arteriole
from renal
artery
Glomerulus
Arteriole
from
glomerulus
1 Proximal tubule
Capillaries
3 Distal
tubule
Branch of
renal vein
From
another
nephron
Collecting
duct
2 Loop of Henle
with capillary
network
Overview: The key processes of the urinary
system are filtration, reabsorption,
secretion, and excretion
 Filtration
– Blood pressure forces water and many small solutes
into the nephron
 Reabsorption
– Valuable solutes are reclaimed from the filtrate
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Overview: The key processes of the urinary
system are filtration, reabsorption,
secretion, and excretion
 Secretion
– Excess H+ and toxins are added to the filtrate
 Excretion
– The final product, urine, is excreted
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Filtration
Nephron tubule
H2O, other small molecules
Capillary
Reabsorption
Secretion
Excretion
Urine
Interstitial fluid
Blood filtrate is refined to urine through
reabsorption and secretion
 Reabsorption in the proximal and distal tubules
removes
– Nutrients
– Salt
– Water
 pH is regulated by
– Reabsorption of HCO3–
– Secretion of H+
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Blood filtrate is refined to urine through
reabsorption and secretion
 High NaCl concentration in the medulla promotes
reabsorption of water
 Antidiuretic hormone (ADH) regulates the
amount of water excreted by the kidneys
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Blood
Filtrate composition
H2O
NaCl
–
Proximal tubule
Bowman’s
Nutrients H2O
capsule
NaCl
HCO3–
1
Distal tubule
NaCl
H2O
HCO3–
K+
Some
H+
drugs
and poisons
H+
3
Collecting
duct
Cortex
Medulla
HCO3
H+
Urea
Glucose
Amino acids
Some drugs
Loop of
Henle
2
NaCl
NaCl
H2O
Reabsorption
Secretion
Filtrate movement
Urea
NaCl
H2O
Urine (to renal pelvis)
Gain water
Lose water
Salt
Freshwater
Fish
Osmosis
Excretion
Pump in
Saltwater Fish
Drinking
Osmosis
Excrete,
pump out
Land Animal
Drinking,
eating
Evaporation,
urinary system
Urea
Kidney
Ureter
Bladder
Homeostasis
involves processes of
(a)
(c)
(b)
animal may
be
maintains
balance of
both done by
involves
removal of
human
kidney
nitrogenous
wastes
water and
solutes
requirements
depend on
(d)
(e)
endotherm
mechanisms
mostly
form may be
(g)
mechanisms
include
(h)
depends on
(i)
may be
heat production,
insulation,
countercurrent
heat exchange
(f)
ocean, fresh water,
land
reproduction
(where embryo
develops)
(a)
(b)
(c)
Bowman’s
capsule
From renal
artery
To renal
vein
Glomerulus
Collecting duct
Tubule
Capillaries
Loop
of Henle
(d)
You should now be able to
1. Compare the osmoregulatory problems of freshwater fish,
saltwater fish, and terrestrial animals.
2. Compare the three ways that animals eliminate
nitrogenous wastes.
3. Describe the structure of the human kidney.
4. Explain how the kidney promotes homeostasis.
5. Describe four major processes that produce urine.
6. Describe the key events in the conversion of filtrate into
urine.
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