Incomplete loop of henle in birds

[sw2kool]

Birds are said to have incomplete loop of henle. What does this mean and how does this help in water conservation? shouldn't they have long loops?

---

Members don't see this ad.

 

[SaCkO]

Birds are said to have incomplete loop of henle. What does this mean and how does this help in water conservation? shouldn't they have long loops?

If they have an incomplete loop of henle, then i would understand it as having a shorter loop of henle.. The loop of henle serves to concentrate the medullary interstituim so that urine is concentrated when it passes through DCT and collecting duct.
So if they have shorter loop of henle then they cannot ultra concentrate their urine and their urine remains dilute.
On the other hand, Rodents have a very long loop of henle which makes them ultra concentrate their urine and preserve the water in their body, thus they need less water to live .

 

[sw2kool]

If they have an incomplete loop of henle, then i would understand it as having a shorter loop of henle.. The loop of henle serves to concentrate the medullary interstituim so that urine is concentrated when it passes through DCT and collecting duct.
So if they have shorter loop of henle then they cannot ultra concentrate their urine and their urine remains dilute.
On the other hand, Rodents have a very long loop of henle which makes them ultra concentrate their urine and preserve the water in their body, thus they need less water to live .

those were my thoughts exactly. incomplete should mean shorter. but we also know birds excrete primarily uric acid, doesn't that mean that water re absorption is high? birds do need to conserve water quite a bit to survive too, especially those with long flight times right?

 

[SaCkO]

those were my thoughts exactly. incomplete should mean shorter. but we also know birds excrete primarily uric acid, doesn't that mean that water re absorption is high? birds do need to conserve water quite a bit to survive too, especially those with long flight times right?

Birds have other glands that help in osmoregularion .. I copied this from a paper
http://jeb.biologists.org/content/47/3/375.1.full.pdf


Animals exposed to desert and salt-water environments must be able to excrete
waste products and electrolytes and at the same time maintain a state of positive water
balance. The kangaroo rat for example, which is both behaviourally and physiologically adapted to its normally arid environment, excretes an extremely hypertonic
urine, and even when given sea water is able to eliminate the excess electrolytes without
incurring an undue loss of water (Schmidt-Nielsen & Schmidt-Nielsen, 1950). Such
renal concentrating abilities are made possible by the double counter-current arrangement of the loop of Henle, the collecting ducts and the vasa recta (Wirz, Hargitay &
Kuhn, 1951). The loop of Henle, however, is incompletely developed or absent in
many nephrons of the bird kidney (Sperber, i960), and although many species appear
able to produce a hypertonic urine the concentrating capacity of the kidney is considerably less than that of the mammal. Consequently, we find that when birds such
as the pigeon are infused with hypertonic saline they undergo a progressive dehydration (Scothorne, 1959).

http://jeb.biologists.org/content/47/3/375.1.full.pdf

 

[sw2kool]

i see. thank you.