Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.
-
Upload
homer-lawrence -
Category
Documents
-
view
231 -
download
0
Transcript of Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.
![Page 1: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/1.jpg)
Osmoregulation by Birds
Eldon J. BraunDepartment of PhysiologyUniversity of Arizona
![Page 2: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/2.jpg)
Maintenance of the Internal Environment
Osmoregulation means the maintenanceof the homeostasis of internal environment.
What constitutes the internal environment?
![Page 3: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/3.jpg)
Birds osmoregulated well
Birds inhabit all environments
Aquatic
Fresh water
Marine
Estuaries
Terrestrial
Polar
Temperate
Desert
![Page 4: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/4.jpg)
In terms of osmoregulation, mammals are the unusual group
Kidneys are only osmoregulatory organ
Osmoregulation among other vertebrates
Fish, amphibians, reptiles, and birds
Multiple organs function in osmoregulation
![Page 5: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/5.jpg)
ORGANS THAT CONTRIBUTE TO OSMOREGULATION IN VERTEBRATES
Group Osmoregulatory Organs Fish Kidneys Gills Bladder Intestine Amphibians Kidneys Gills Bladder Skin Intestine Reptiles Kidneys Salt Glands Intestine Birds Kidneys Salt Glands Intestines Mammals Kidneys
![Page 6: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/6.jpg)
Osmoregulation by birds: Organs Involved
Kidneys
Lower gastrointestinal tract
Salt glands
![Page 7: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/7.jpg)
Avian salt glands
![Page 8: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/8.jpg)
The avian renal and gastrointestinal systems must function in concert in the regulation of ion and fluid balance.
![Page 9: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/9.jpg)
![Page 10: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/10.jpg)
As birds do not have urinary bladders, the ureteral urine is refluxed from the cloaca into colon
![Page 11: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/11.jpg)
![Page 12: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/12.jpg)
Evolutionary Rationale for this Type of Arrangement
Excess mass of urinary bladder
GFRs of Birds and Mammals Do Not Differ
Fraction of Filtered Water Reabsorbed by Kidney
Less by Avian Kidney
Urine of Birds in Constant “Flux”
(i.e. urine entering lower GI tract)
Argument does not “hold water”
![Page 13: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/13.jpg)
Urine to plasma osmolar ratio
How well kidneys of animals concentrate urine isUsually expressed as the ratio of the urine osmolalityTo the plasma osmolality.
Or simply the U/Posm
![Page 14: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/14.jpg)
Birds or the avian kidney does not concentrate urine to a high degree
![Page 15: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/15.jpg)
Maximum U/Posms of some mammals
Values range from about 1 in the Mountain Beaver to ca. 25 in some of the small desert Rodents.
Humans U/Posm?
![Page 16: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/16.jpg)
Urine-to-Plasma Osmolar Ratios for Birds (U/Posm)
Ring-necked Pheasant 1.5Senegal Dove 1.7Savannah Sparrow 1.7King Quail 1.8White-crowned Sparrow 1.8Domestic Fowl 2.0Budgerigar 2.3House Finch 2.4Singing Honeyeater 2.4Stubble Quail 2.6
Mean 2.05
![Page 17: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/17.jpg)
Comparison of U/Posms between birds and mammals
Not valid comparison to make Urine in lower GI tract
End products of nitrogen metabolism Uric acid vs. urea
Effects of conc. fluid in lower GI tract
Urea ca. 50% of solutes in urineUric acid not in solution
![Page 18: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/18.jpg)
Plasma and urine osmolality of Desert Quail
![Page 19: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/19.jpg)
Nitrogen Excretion in Birds
Compound PercentUrea 4Ammonium 20Uric Acid 76
![Page 20: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/20.jpg)
Solubilites of Nitrogen-Containing Compounds
Compound Solubility (mmol/L)
Uric Acid 0.381
Ammonium Urate 3.21
Sodium Urate 8.32
Potassium Urate 14.75
Urea 16,650
![Page 21: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/21.jpg)
Structure of Uric Acid
![Page 22: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/22.jpg)
Evolutionary Rationale for this Type of Arrangement(i.e. urine entering lower GI tract)
Crystal of Uric Acid
![Page 23: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/23.jpg)
Evolutionary Rationale for this Type of Arrangement(i.e. urine entering lower GI tract)
Physical form of uric acid in avian urine
Small spherical structures
Spheres ca. 65%uric acid
Uric acid boundTo a matrix protein
![Page 24: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/24.jpg)
Prevention of Sphere Coalescence
Protein in avian ureteral urine
Avian urine contains 5 mg/ml protein
Protein conc. in human urineca. 0.05 mg/ml
![Page 25: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/25.jpg)
Nature of Protein in Urine of BirdsSDS PAGE of avian Urine and plasma
![Page 26: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/26.jpg)
Energy in Avian Ureteral Urine
Male Female
Kcal/Day 5.3 12.4
% BMR 5.4 11.3
![Page 27: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/27.jpg)
SDS PAGE of Avian Excreted Fluid
![Page 28: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/28.jpg)
Modification of Urine in Lower GI Tract of Birds
Anderson & Braun
![Page 29: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/29.jpg)
Degradation of Uric Acid in Lower GI Tract
68% of uric acid in ureteral urine
Bacterial action
• Fate of liberated nitrogen
o Glutamic acid
Renal tubules--Buffer H ions Gluconeogensis Citric acid cycle
o Short chain volatile fatty acids
![Page 30: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/30.jpg)
Products Formed From the Breakdown of Uric Acid in Avian Lower GI tract
77% of [15N]uric acid introduced into ceca of cockerelsdisappeared in 60 min
And nitrogen appeared as ammonia and rapidly absorbed
Karasawa, 1989
Labelled nitrogen appeared in plasma within glutamine
Where do these product go?
![Page 31: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/31.jpg)
Vasculature Surrounding the Avian Kidney
Akester
Coccygomesenteric veindrains into renal portal system
Birds have a functional renal portal system
![Page 32: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/32.jpg)
Tubule Lumen Cells Peritubule Side
Blood fromrenal portalsystem
Glutamine
Glutamine
NH3NH3
Na+
H+H+
NH4+
Use of glutamine by renal tubules (To buffer hydrogen ions)
![Page 33: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/33.jpg)
Proteins
Amino Acids
Pyruvate
Acetyl CoA
Citric Acid cycle
Glyceraldehyde3-phosphate
Glucose
Fatty Acids
Ammonia
Possible Pathway for Utilization of Uric Acid
Also, deamination of glutamine produces ketoglutaric acid that can enter the krebs cycle
![Page 34: Osmoregulation by Birds Eldon J. Braun Department of Physiology University of Arizona.](https://reader036.fdocuments.in/reader036/viewer/2022062720/56649f125503460f94c25553/html5/thumbnails/34.jpg)
Summary
Birds osmoregulate wellMultiple organ systems contribute to osmoregulation in birds
Salt glandsKidneysGastrointestinal tract
Uric acid as an end product to nitrogen metabolismForm of uric acid in urine“Value” of uric acidRecycling of the nitrogen of uric acid