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Osmoregulatie bij water- en landverebraten

Q: Does cell volume increase or decrease with hypoosmotic environments? And with hyperosmotic environments?

With hypoosmotic environments, cell volume will rise and with hyperosmotic environments, cell volume will decrease .

Q: What are osmoconformers? Name examples of osmoconformers.

Animals that cannot regulate their internal osmotic pressure . Their bodies are permeable to salts and water, and their body fluid concentration rises or falls with changes in the concentrations of seawater. Examples: sharks, marine invertebrates like starfish, mussels, crabs, lobsters and jellyfish.

Q: What are stenohalines? Name examples.

These animals are restricted to living in a narrow salinity range because they cannot withstand osmotic change . When they are exposed to diluted seawater, they absorb the water by osmosis and die quickly because their body's cells cannot tolerate dilution and are helpless to prevent it. Examples: fish (goldfish (freshwater), haddock (seawater)).

Q: What are euryhalines? Name examples.

These animals can survive a wide range of salinity changes , mainly by having various powers of osmoregulation . Examples: Green crab, molly fish.

Q: What are hyperosmotic regulators?

Animals that maintain its body fluids more concentrated (-more hyper) than the surrounding water . E.g. brackish-water shore crab.

Q: Why are fresh water fishes efficient hyperosmotic regulators?

They must keep the salt concentration of their bodies higher than that of the water in which they live. Water enters their body osmotically, and salt is lost by outward diffusion. To regulate this, they are efficient hyperosmotic regulators.

Q: What are the defenses of freshwater fish against water gain and salt loss?

Water that enters the body via osmosis is pumped out by the kidney , which can form very dilute urine by reabsorbing NaCl. Salt-absorbing cells located in the gills transport salt ions , (mainly Na and Cl) from the water to the blood . This salt + the salt from food replaces diffusive salt loss. This is all very efficient and a freshwater fish only spends a small part of its energy on osmoregulation.

Q: What are hypoosmotic regulators?

Animals that keep their body fluids at a lower (-hypo) osmotic concentration than the environment . E.g. bony fish.

Q: How do hypoosmotic regulators compensate for water loss and salt gain?

By drinking seawater . The salt from the water is absorbed from the intestine and is carried by the blood to the gills. Here specialized salt-secreting cells transport it back into the surrounding sea . Excess salts in the intestine are secreted through feces of the kidneys .

Q: How do sharks and rays (elasmobranchs) regulate their osmotic balance?

The blood carries trimethylamine oxide (TMAO) and urea which raises the blood osmolarity to equal or slightly higher than that of seawater . Water balance is therefore not a problem anymore and they are in osmotic equilibrium with their environment.

12 important questions on Osmoregulatie bij water- en landverebraten

Does cell volume increase or decrease with hypoosmotic environments? And with hyperosmotic environments?

With hypoosmotic environments, cell volume will rise and with hyperosmotic environments, cell volume will decrease.

What are osmoconformers? Name examples of osmoconformers.

Animals that cannot regulate their internal osmotic pressure. Their bodies are permeable to salts and water, and their body fluid concentration rises or falls with changes in the concentrations of seawater.
Examples: sharks, marine invertebrates like starfish, mussels, crabs, lobsters and jellyfish.

What are stenohalines? Name examples.

These animals are restricted to living in a narrow salinity range because they cannot withstand osmotic change. When they are exposed to diluted seawater, they absorb the water by osmosis and die quickly because their body's cells cannot tolerate dilution and are helpless to prevent it.
Examples: fish (goldfish (freshwater), haddock (seawater)).

What are euryhalines? Name examples.

These animals can survive a wide range of salinity changes, mainly by having various powers of osmoregulation.
Examples: Green crab, molly fish.

What are hyperosmotic regulators?

Animals that maintain its body fluids more concentrated (-more hyper) than the surrounding water. E.g. brackish-water shore crab.

Why are fresh water fishes efficient hyperosmotic regulators?

They must keep the salt concentration of their bodies higher than that of the water in which they live. Water enters their body osmotically, and salt is lost by outward diffusion. To regulate this, they are efficient hyperosmotic regulators.

What are the defenses of freshwater fish against water gain and salt loss?

Water that enters the body via osmosis is pumped out by the kidney, which can form very dilute urine by reabsorbing NaCl.
Salt-absorbing cells located in the gills transport salt ions, (mainly Na and Cl) from the water to the blood. This salt + the salt from food replaces diffusive salt loss.

This is all very efficient and a freshwater fish only spends a small part of its energy on osmoregulation.

What are hypoosmotic regulators?

Animals that keep their body fluids at a lower (-hypo) osmotic concentration than the environment. E.g. bony fish.

How do hypoosmotic regulators compensate for water loss and salt gain?

By drinking seawater.
The salt from the water is absorbed from the intestine and is carried by the blood to the gills. Here specialized salt-secreting cells transport it back into the surrounding sea. Excess salts in the intestine are secreted through feces of the kidneys.

How do sharks and rays (elasmobranchs) regulate their osmotic balance?

The blood carries trimethylamine oxide (TMAO) and urea which raises the blood osmolarity to equal or slightly higher than that of seawater. Water balance is therefore not a problem anymore and they are in osmotic equilibrium with their environment.

How do terrestrial animals replace water loss?

By consuming water in food, drinking water, and retaining metabolic water formed in cells by oxidation of metabolic fuels such as carbohydrates and fats.

What is the efficient solution of turtles and marine birds for excreting large loads of salt that they eat?

They have a salt gland located above each eye that is capable of excreting a highly concentrated solution of NaCl. They shed their salt-gland secretion as salty tears. This is important because their kidneys cannot produce a concentrated urine.

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MD2

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Osmoregulatie bij water- en landverebraten

12 important questions on Osmoregulatie bij water- en landverebraten

Does cell volume increase or decrease with hypoosmotic environments? And with hyperosmotic environments?

What are osmoconformers? Name examples of osmoconformers.

What are stenohalines? Name examples.

What are euryhalines? Name examples.

What are hyperosmotic regulators?

Why are fresh water fishes efficient hyperosmotic regulators?

What are the defenses of freshwater fish against water gain and salt loss?

What are hypoosmotic regulators?

How do hypoosmotic regulators compensate for water loss and salt gain?

How do sharks and rays (elasmobranchs) regulate their osmotic balance?

How do terrestrial animals replace water loss?

What is the efficient solution of turtles and marine birds for excreting large loads of salt that they eat?

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