4/1 Daily Catalyst Page
102 Osmoregulation
 1. Name two systems we have seen countercurrent exchange in.
 2. Calculate the probability of tossing three coins
simultaneously and obtaining three heads. Express in fraction
form.
4/1 Daily Catalyst Page
102 Osmoregulation
 1. Name two systems we have seen countercurrent exchange
in.
 Thermoregulation and the respiratory system
 Vasodilation and vasoconstriction
 Blood and water flow in opposite directions to one another
 2. Calculate the probability of tossing three coins
simultaneously and obtaining three heads. Express in fraction
form.
4/1 Class Business Page
102 Osmoregulation
 Spring Break packet due Tuesday, April 7th
 Email me or text me with questions
 Use your book and notes
 Immune system on Tuesday
4/1 Agenda Page
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Daily Catalyst
Class Business
Reading quiz
Osmoregulation notes
Quiz #26
102 Osmoregulation
4/1 Reading Quiz
 Name: _________ Date: 4/1 Score: _______/4
 1. How do fish balance water loss?
 2. In freshwater fish, why do they uptake salt by their
gills?
 3. How do sharks lose excess salt?
 4. As mammals, how do we excrete nitrogenous
waste?
4/1 Reading Quiz
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1. How do fish balance water loss?
They drinks lots of water
2. In freshwater fish, why do they uptake salt by their gills?
In freshwater, there is a lack of salt, so the fish get the salt
they need from NaCl in the water
3. How do sharks lose excess salt?
Kidneys remove salt, lost in feces, and excreted by the
rectal gland
4. As mammals, how do we excrete nitrogenous waste?
Urea
4/1 Objective
 Homeostatic control systems in species
of microbes, plants, and animals
support common ancestry.
Osmoregulation in
bacteria, fish, and protists.
 Day after day, day after day,
 We stuck, nor breath nor motion;
 As idle as a painted ship
 Upon a painted ocean.
 Water, water, every where,
 And all the boards did shrink;
 Water, water, every where,
 Nor any drop to drink.
Osmoregulation and Excretion
 The cell relies on the aqueous environment!
 H2O and Solute [ ] is maintained within a narrow range
 = HOMEOSTASIS
Key Point #1:
 What about waste from metabolism?
 Key Point #1: Two key processes:
 Osmoregulation
 Solute [ ] regulation by the uptake and loss of H2O
 Excretion
 Losing nitrogen containing wastes
44.1 Osmoregulation balances the
uptake and loss of water and solutes
 Osmoregulation
 Solute [ ] regulation by the uptake and loss of H2O
 HOW?
 Control MVMT of solutes from in and out of the cell
BECAUSE…
 Water follows solutes
 OSMOSIS
Osmosis
 The movement of water
 Passive transport (no ATP)
 High to low concentration
Osmosis
Outside the cell
Inside the cell
Osmotic Challenges
 Key Point #2: Osmoconformer
 Internal environment isotonic with the environment
 A stable environment is essential
 Common in marine fish
 Key Point #3: Osmoregulator
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Internal environment is not isotonic with environment
Must control its own osmolality
Very expensive
Common in freshwater and terrestrial organisms
Brine Shrimp
Osmoregulation
Marine Fish
 Most are osmoconformers
 Ocean is dehydrating!
 Drink lots of water and gain
salts by diffusion
 Kidneys excrete lil water
Freshwater Fish
 Mostly osmoregulators
 Constantly gain H2O by
osmosis and lose salts by
diffusion (lack of salt in the
habitat)
 Salt needs are lower
 Reduces energy cost
Bacteria
 Rapidly take in salt or
electrolytes through their cell
membrane
Protists
 Vacuoles remove waste as the
H2O enters the cell membrane
Turn and Talk
 The movement of salt from the surrounding
water the blood of a freshwater fish requires
the expenditure of energy in the form of ATP.
Why?
44.2 An animal’s nitrogenous wastes
reflect its phylogeny and habitat
 Key Point #4: Most important waste is nitrogenous
breakdown of proteins and nucleic acids
 Most nitrogen is removed as AMMONIA (NH3)
 Super toxic
Ammonia
 Ammonia:
 Aquatic animals
 Why?
 Ammonia is toxic and need access to lots of water for dilution
 Ammonium ions (NH4+)
Urea
 Urea:
 Common in mammals, sharks, amphibians, turtles, and some
fish
 Produced in the liver
 NH3 + CO2 to be excreted in the kidneys
 Low toxicity
 Costly
Think-pair-share
 What role does the vertebrate liver play in the
body’s processing of nitrogenous waste?
Uric Acid
 Uric Acid:
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Common in insects, land snails, reptiles, and birds
Non toxic
Insoluble in water so it forms a paste
VERY COSTLY! (more than urea)
Turn and Talk
 What advantage does uric acid offer as a
nitrogenous waste in arid
environments?
Influence of evolution on N2 waste
 The kind of waste excreted, depends on the animal’s
evolutionary history and habitat.
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Availability of H2O
Environment (food sources)
Reproduction
Age
 Who would you expect to produce more waste,
endotherms or ectotherms?
 Endotherms eat more food and produce more waste
Find a partner
 Dragonfly larvae, which are aquatic, excrete
ammonia, whereas adult dragonflies, which are
terrestrial, excrete uric acid. Explain.
Find a partner
 Why are no freshwater animals
osmoconformers?
Find a classmate
 What advantage does uric acid offer as a
nitrogenous waste in arid environments?
 Arid- dry, lack of water
 Uric acid has an advantage over Ammonia and
Urea because, Uric acid is nontoxic and does
not need to be diluted like ammonia. Even
though it is nontoxic, it is energy costly.
Share Out
 What role does the vertebrate liver play in the
body’s processing of nitrogenous waste?
 Urea is produced in the liver and will travel to
the kidneys where water is added (little or a
lot) and the body excretes the liquid (urine)
44.3 Diverse Excretory Systems
are variations on a tubular theme
 The excretory process:
 Body fluid is brought into contact with a membrane of the
excretory system
 Proteins and large molecules CANNOT cross the membrane
 Water, salt, sugar, and amino acids CAN cross
 Forms the filtrate
 The “good stuff” is reabsorbed by the body (amino acids,
vitamins, and glucose)
 Waste is released as urine
 The systems that perform the basic excretory
functions vary widely among animal groups.
 Similarity?
 Network of tubules that provide A LARGE SURFACE
AREA for exchange!
Flatworms (Protonephridia)
 Network of tubules that connect to external openings
 Flame cells form the “caps”
 Cilia
 Draws water and solutes in
 Filtrate in the tubules
 Empties “urine”
Earthworms (Metanephridia)
 Excretory organs open internally to the coelom
 Coelom??
 A body cavity
Earthworms (Metanephridia)
 As cilia beat, fluid is drawn into the tubules, into the bladder,
and excreted outside
 Tubules excrete nitrogenous waste
 Intake water by their skin (osmosis)
Kidneys
 Kidneys function in osmoregulation and excretion!
 In vertebrates
 Has tubules too!
 I mean, A LOT of tubules
Mammalian Excretory System
Stop and Jot
 Compare and contrast the different ways that metabolic
waste products enter the excretory systems of flatworms,
earthworms, and insects.
 What happens when feedback loops do not work very
well?
 We have seen this in blood clotting, insulin and diabetes, and
now….
 Example
 Dehydration in response to decreased antidiuretic
hormone (ADH)
 What is a diuretic?
Antidiuretic Hormone
 Produced in the hypothalamus
 Stored in the pituitary gland
ADH
 Function:
 To conserve water loss in urine
ADH
 After ingesting a salty meal, the blood osmolality rises.
 The concentration of solutes
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ADH is released into the bloodstream.
ADH reaches the kidney and it ATTACKS the tubules!
Water is reabsorbed FROM the kidney
Concentrates urine, reduced urine volume, and we dilute our blood!
ADH
 Guess what?!
 Yes, Negative feedback loops!
 As the osmolality of water subsides, a negative feedback
mechanism reduces the activity of osmoreceptors cells in
the hypothalamus, and ADH secretion is reduced.
ADH
 What about when blood osmolality decreases?
 No need for ADH
 Large volume of water and dilute urine
ADH
 What is the effect of a mutation preventing the
production of ADH?
 Mutation in aquaporin's
 DEHYDRATION!
 Urine that is large in volume and very dilute
 These mutations can lead to DIABETES (more on this later)
 What else can lead to decreased ADH amounts?
 Alcohol
 Excessive water loss and dehydration (hangover)