L15 - Osmoregualtion Flashcards Preview

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Flashcards in L15 - Osmoregualtion Deck (12)
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1
Q

How is the volume of fluid and the concentration of solutes maintained between narrow limits in an organism?

A

1) the ability to change membrane permeability
2) Decreasing the conc grad between body fluids and the environment
3) Active Transport of ions

2
Q

What is an Osmoconformer?

A

An organism that keeps it body fluid similar to the external environment

Most marine invertebrates have body fluids that are iso-osmotic with seawater, but many still have to regulate individual ion concentrations using pump mechanism in the gills and gut

3
Q

What is an osmoregulator?

A

An organism that can maintain a body fluid osmolality that is different from the external environment

4
Q

Give the problems facing, and solutions made by hypo-osmoregulating invertebrates

A

Problems:

  • water loss
  • salt gain

Solutions:

  • reduce permeability (rare solution method)
  • low urine output
  • drinking
  • active excretion of salts
5
Q

Give the problems facing, and solutions made by hyper-osmoregulating invertebrates

A

Problems:

  • water gain
  • salt loss

Solutions:

  • reduce permeability
  • excrete excess water
  • dilute urine
  • active absorption of ions
6
Q

Give 3 examples of vertebrates that are osmoconformers

A

1) Elasmobranchs (sharks and rays)
2) Coelacanth
3) Crab eating frog - their skin is very think which can lose/gain ions and water very quickly

7
Q

Some vertebrate osmoconformers use urea retention to achieve iso-osmotic ECF. What are the 3 adaptations do they have to be able to do this?

A

1) Low urine flow rate
2) A degree of tolerance to urea (high urea destabilises protein structure)
3) MAIN POINT - make counteracting solutes such as TMAO (Trimethylamineoxide) - this after urea destabilise proteins, with stabilise/reverse them back

8
Q

What is the [NaCl] of the blood of elasmobranchs and coelacanths in comparison to seawater?

A

[NaCl] of the blood is around 30% of that of seawater

9
Q

What 3 organs is Na+ excreted out in elasmobranchs and coelacanths?

A

1) Rectal gland
2) Kidney
3) Gills - chloride cells - contain many Na+/K+ ATPase’s

10
Q

In freshwater all vertebrates are ____________

A

Osmoregulators (all are hyperosmotic - their body fluids have a higher osmotic pressure than the external environment)

11
Q

What is a T.E.P and how is it created in a Chloride cell?

A

T.E.P = Trans epithelial potential

It is created by a symport on the apical membrane pumping Na+ and K+ into the cell. Cl- follows down an electrical gradient and then moves through the cell and out the other side through a CL- channel. This creates high [Na+] and [K+] at the apical side, and high [Cl-] at the basal side, which creates a difference in potential, around 20-30mV

12
Q

How do each excrete salt?

a) marine iguanas and seabirds
b) Terrapins
c) Sea snakes

A

a) Through nasal salt glands
b) lacrimal glands
c) Sublingual glands (salivary glands)