Controlling the internal environment ii salt and water balance
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Controlling the Internal Environment II: Salt and water balance. Ammonia toxicity Urea Uric acid Osmoconformer Osmoregulator Passive transport Facilitated diffusion Active transport Uniport Antiport symport. Osmoregulation by an aquatic invertebrate Osmoregulation in marine fish

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Controlling the Internal Environment II: Salt and water balance

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Keywords reading p 879 884 l.jpg

Ammonia toxicity balance

Urea

Uric acid

Osmoconformer

Osmoregulator

Passive transport

Facilitated diffusion

Active transport

Uniport

Antiport

symport

Osmoregulation by an aquatic invertebrate

Osmoregulation in marine fish

Osmoregulation in freshwater fish

Water loss on land

Permeable and impermeable body surfaces

Kangaroo rate water balance

anhydrobiosis

Keywords (reading p. 879-884)


The internal environment l.jpg
The internal environment balance

  • In most animals, the majority of cells are bathed by internal fluids rather than the environment

  • This is advantageous since there can be control of substrates needed for metabolism





Control of substrate concentration products do not diffuse away l.jpg
Control of substrate concentration membrane and became a cellProducts do not diffuse away


Slide8 l.jpg

Hazardous products


Therefore the internal chemical environment is controlled l.jpg
Therefore the internal chemical environment is controlled the products

  • A. Avoiding buildup of toxic chemicals

    • Dealing with ammonia

  • B. Osmoregulation - controlling internal solutes



Hazardous products l.jpg
Hazardous products the products

  • A major source of hazardous products is the production of nitrogenous wastes

  • Ammonia (NH3) is a small and very toxic molecule that is normal product of protein and amino acid breakdown

  • If you are an aquatic organism, ammonia can readily diffuse out of the body and this is not a problem


Ammonia toxicity is a problem for terrestrial animals l.jpg
Ammonia toxicity is a problem for terrestrial animals the products

  • Ammonia does not readily diffuse away into the air.

  • The strategy of terrestrial animals is to detoxify it then get rid of (excrete) it.


Ammonia can be converted to urea which is 100 000 times less toxic l.jpg
Ammonia can be converted to urea which is 100,000 times less toxic

  • Mammals, most amphibians, sharks, some body fishes


The drawback of using urea l.jpg
The drawback of using urea toxic

  • Takes energy to synthesize

  • Still need to use water to “flush it out”


Some animals cannot afford to use water to excrete urea l.jpg
Some animals cannot afford to use water to excrete urea toxic

  • These animals use excrete uric acid instead


Uric acid l.jpg
Uric acid toxic

  • Since uric acid is not very soluble in water, it can be excreted as a paste.

  • Less water is lost

  • Disadvantages:

    • Even more costly to synthesize.

    • Loss of carbon


Who uses uric acid l.jpg
Who uses uric acid? toxic

  • Birds, insects, many reptiles, land snails

  • Related to water use, but also reproduction

  • Eggs - N wastes from embryo would accumulate around it if ammonia or urea are used. Uric acid precipitates out.



Osmolarity l.jpg
Osmolarity toxic

  • Osmolarity = # of solutes per volume solution

  • Often expressed in moles (6.02 x 1023 atoms/molecules) per liter.

  • 1 mole of glucose = 1 mole of solute

  • 1 mole of NaCl = 2 moles of solute


Osmotic problems l.jpg
Osmotic problems toxic

  • Humans have internal solute concentration (osmolarity) of 300 milliosmoles per liter (mosm/L)

  • The ocean is 1000 mosm/L


What would happen if your body surface is water permeable and you fall into the sea l.jpg

Keep your internal concentrations the same as the environment (osmoconformer)

Regulate your internal concentrations (osmoregulator)

What would happen if your body surface is water permeable and you fall into the sea

1000 mosm/L

300 mosm/L


Jellyfish in the ocean l.jpg
Jellyfish in the ocean environment (osmoconformer)

  • Keep solutes at 1000 mosm/L no water loss or gain.

  • A relatively simple solution

1000 mosm/L

1000 mosm/L

jellyfish


Life in freshwater hydra living in a pond l.jpg
Life in freshwater - hydra living in a pond environment (osmoconformer)

  • Can the same strategy of matching the environmental osmolarity be used?

0 mosm/L

0 mosm/L

Green hydra


Hydra living in a pond l.jpg
Hydra living in a pond environment (osmoconformer)

  • If external osmolarity is very low like 0 mosm/L, hydra cannot maintain an internal osmolarity of 0 mosm/L

  • Why is this?

  • Consequently freshwater animals will most likely have a higher osmolarity than the environment.


What happens to freshwater organisms l.jpg
What happens to freshwater organisms? environment (osmoconformer)

  • Water from the environment is continually entering tissues.

  • The diffusion gradient favors loss of solutes

  • Therefore there is a need to regulate solutes and water


Two ways to deal with osmotic problems l.jpg
Two ways to deal with osmotic problems environment (osmoconformer)

  • Keep your internal concentrations the same as the environment (osmoconformer)

  • Regulate your internal concentrations (osmoregulator)


Solute regulation l.jpg
Solute regulation environment (osmoconformer)

  • Transport solutes across the body surface

    • Note: even in the jellyfish example, there is ion regulation. Although the internal fluids have the same osmolarity as seawater, they do not have the same composition


Ways molecules get across membranes l.jpg
Ways molecules get across membranes environment (osmoconformer)


Passive transport diffusion l.jpg
Passive transport: Diffusion environment (osmoconformer)

  • Works for lipid soluble molecules and gases

  • No good for most water soluble molecules and ions


Passive transport facilitated diffusion l.jpg
Passive transport: Facilitated diffusion environment (osmoconformer)

  • Generally used for ions, larger molecules, non-lipid soluble molecules.

  • Must be a gradient favoring diffusion


Active transport l.jpg
Active transport environment (osmoconformer)

  • Works for ions and molecules like glucose or amino acids

  • Can transport against a gradient.

  • Costs energy, usually ATP


In this diagram how might sodium get across the membrane l.jpg
In this diagram, how might sodium get across the membrane? environment (osmoconformer)

  • A) diffusion

  • B) active transport

  • C) facilitated diffusion or active transport

Na+

Na+

Na+

Na+


In this diagram how might sodium get across the membrane34 l.jpg
In this diagram, how might sodium get across the membrane? environment (osmoconformer)

  • A) diffusion

  • B) active transport

  • C) facilitated diffusion or active transport

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+

Na+


In this diagram how might sodium get across the membrane35 l.jpg
In this diagram, how might sodium get across the membrane? environment (osmoconformer)

  • A) diffusion

  • B) active transport

  • C) facilitated diffusion or active transport

Na+

Na+

Na+

Na+

- - - - - - - - - - - - -

+ + + + + + + + + +

Na+

Na+


In this diagram how might steroids get across the membrane l.jpg
In this diagram, how might steroids get across the membrane? environment (osmoconformer)

  • A) diffusion

  • B) active transport

  • C) facilitated diffusion

  • D) all of the above

steroid

steroid

steroid

steroid

steroid


In this diagram how might steroids get across the membrane37 l.jpg
In this diagram, how might steroids get across the membrane? environment (osmoconformer)

  • A) diffusion

  • B) active transport

  • C) facilitated diffusion

  • D) all of the above

steroid

steroid

steroid

steroid

steroid

steroid

steroid

steroid

steroid

steroid

steroid

steroid

steroid

steroid

steroid


Types of active transport l.jpg
Types of active transport environment (osmoconformer)


What type of active transport is this l.jpg
What type of active transport is this? environment (osmoconformer)

  • A) uniport

  • B) symport

  • C) antiport

K+


What type of active transport is this40 l.jpg
What type of active transport is this? environment (osmoconformer)

  • A) uniport

  • B) symport

  • C) antiport

K+

Sodium potassium ATPase

Na+


What type of active transport is this41 l.jpg
What type of active transport is this? environment (osmoconformer)

Cl-

  • A) uniport

  • B) symport

  • C) antiport

K+


Responses of soft bodied invertebrates to changes in salinity l.jpg
Responses of soft-bodied invertebrates to changes in salinity

  • Marine invertebrates can often be exposed to salinity changes (e.g., tidepool drying out, estuaries)

  • If salts enter the body, pump them out using transporters

  • If salts are leaving body, take them up from the environment using transporters

  • Or just let your internal concentrations follow changes in the environment


Dumping pumping amino acids l.jpg
Dumping/pumping amino acids salinity

  • One way to respond while keeping internal ion concentrations the same is to pump amino acids out.

  • Often used by bivalves living in estuaries

    • Clams, oysters, mussels


Estuary high tide l.jpg
Estuary - high tide salinity

1000 mosm/L

1000 mosm/L

aa

aa

aa

aa

aa

aa

aa

aa


Estuary low tide l.jpg
Estuary - low tide salinity

500 mosm/L

1000 mosm/L

aa

aa

aa

aa

aa

aa

aa

aa


Estuary low tide46 l.jpg
Estuary - low tide salinity

500 mosm/L

500 mosm/L

aa

aa

aa

aa

aa

aa

aa

aa


Advantages of amino acid osmoregulation l.jpg
Advantages of amino acid osmoregulation salinity

  • Changing amino acid concentrations is less disruptive on internal processes (enzyme function).

  • Costs: pumping amino acids (can involve ATP), loss of amino acids (carbon and nitrogen)


Osmoregulation in other aquatic organisms l.jpg
Osmoregulation in other aquatic organisms salinity

  • Example: fishes maintain internal concentration of solutes

  • Body volume does not change

  • Involves energetic cost of active transport

  • In bony fishes this can be 5% of metabolic rate


Marine fishes l.jpg
Marine fishes salinity


Marine fishes50 l.jpg
Marine fishes salinity

  • Problem: lower internal osmolarity than seawater

  • Water will leave body, sea salts will go in

  • Solution: Fish drink large amounts of seawater, then transport out ions (Na+, Cl-) at their gill surface or in urine (Ca++, Mg++, SO4--).



Freshwater fishes52 l.jpg
Freshwater fishes salinity

  • The opposite situation: tendency to lose solutes and gain water

  • Solutions: take up salts in food and by active transport across gills

  • Eliminate water via copious dilute urine production


Water balance on land l.jpg
Water balance on land salinity

  • Unlike aquatic animals, terrestrial animals don’t lose or gain water by osmosis

  • However, water loss or solute gain can be a major problem

  • Cells are maintained at around 300 mosm/L

  • Humans die if they lose 12% of their body water


Why not just prohibit water loss l.jpg
Why not just prohibit water loss? salinity

  • Impermeable surfaces: waxy exoskeleton (insects), shells of land snails, thick skin (vertebrates).

  • Not all surfaces can be impermeable because gas exchange must also occur.

  • Evaporation across respiratory surfaces is only one of the two main causes of water loss

    • The other is urine production


Drinking l.jpg
Drinking salinity

  • Replenishes water that is lost

  • Water can also be gained by moist foods

  • What if there is no water to drink?



Desert kangaroo rat does not drink l.jpg
Desert kangaroo rat does not drink salinity

  • Don’t lose much water

    • Special nasal passages

    • Urine doesn’t contain much water

  • Recovers almost all of the water that results from cellular respiration


Slide58 l.jpg



Anhydrobiosis tardigrades water bears l.jpg
Anhydrobiosis: Tardigrades (water bears) salinity

  • Can lose 95% of their body water


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