Osmoregulation and Excretion

Ainsley Lockhart and Emily Allyn

Osmoregulation: The Basics

• Osmoconformers – Isoosmotic with surroundings• Osmoregulators- Control internal environment

independently from environment• Stenohaline – Animals that cannot tolerate large

changes in external osmolarity• Euryhaline – Animals that can survive large

fluctuation in external osmolarity.

Osmotic Challenges: A Survey

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Osmoregulation: Energy Cost and Other

Mechanisms

• Energy is required for active transport and diffusion of solutes and water

• Transport epithelia is responsible for filtration and reabsorption

Nitrogenous Waste

• Ammonia • Urea• Uric acid• Evolution of each mode

Excretion: The Basics• How excretory systems maintain homeostasis.

• Bodily Fluids -> Filtrate -> Urine

Evolution of Excretory Systems:

Protonephridia • Organisms

– Flatworms(acoelomates)

– Rotifers – Some annelids – Mollusc larvae– Lancelets

• Functions – Metabolic waste excretion

– Osmoregulation– Disposal of nitrogenous waste

• Mechanisms – Tubule network– Flame bulbs

Evolution of Excretory Systems: Metanephridia• Organisms

– Most annelids• Functions

– Metabolic waste excretion

– Osmoregulation• Mechanisms

– Ciliated funnel– Collecting tubule

– Transport epithelium

Evolution of Excretory Systems: Malpighian

Tubules• Organisms

– Insects and other terrestrial arthropods

• Functions – Nitrogenous waste disposal

– Osmoregulation• Mechanism

– transport epithelium

Evolution of Excrtory Systems: Kidneys

• Organisms – Vertebrates and some other chordates

• Functions– Osmoregulation– Metabolic waste excretion

• Mechanism: – Highly organized tubules

– Ducts

Structure Of The Mammalian Excretory

System• Kidneys: renal cortex, renal medulla, nephron

• Renal veins and arteries supply blood

• Urine: Kidneys -> Ureter -> Bladder -> Urethra

Adaptations and Evolution of the Mammalian Kidney

• Gram-negative bacteria• Hagfish and segmented kidneys

Pathway of Filtrate

From Blood Filtrate to Urine

• proximal tubule        

• descending and ascending limb of loop of Henle        

• distal tube        

• collecting duct

Solute Gradients

Kidney Adaptations: Mammals

• The juxtamedullary nephron functions for water conservation

• Long loops of Henle

Kidney Adaptations: Birds and other

Reptiles• Birds

– Juxtamedullary nephrons – Shorter loops of Henle – Uric acid

• Reptiles – Cortical nephrons – Transport epithelium in cloacas– Uric acid.

Kidney Adaptations: Freshwater Fish and

Amphibians

• Freshwater Fish– Many nephrons – Transport epithelium for salt retention

• Amphibians– Water vs. land adaptations

Kidney Adapations: Marine Bony Fish

• Small nephrons with no distal tube

• Small or no glomeruli• Divalent ions flushed out with kidneys, proximal tubules of nephrons

• Monovalent ions flushed out with gills

Contribution of Hormones to the Mammalian Excretory

System• antidiuretic hormones (ADH)• hypothalamus and pituitary( osmoregulator cells in hypothalamus detects rising osmolarity of blood and produces the hormone. Hormone is stored in the pituitary gland)

• distal tubes and collection ducts (aquaphorons) (the ADH binds to aquaphorons in kidney to change the water pemeability of transport epithelial)

Renin-angiotensin-aldosterone system

(RAAS)• juxtaglomerular apparatus (JGA), afferent arteriol ( the afferent arteriol moitors blood volume/ artetiol tension and instructs the JGA which is close by to make angiotensin II)

• adrenal gland (makes aldosterone)

• aldosterone, angiotensin II

Homeostatic Regulation of the Kidney

• The renin-angiotensin-aldosterone system (RAAS)

• Antidiuretic hormones (ADH) • Atrial natriuretic peptide (ANP)

Disorders of the Kidney

• Diabetes insipidus• Affects of alcohol• Gout

References1. "Gout: What You Should Know." American Family

Physician 76.6 (2007): 811-12. Science Full Text Select. H. W. Wilson. Wilson Web Science. 6 Apr. 2009 <http://vnweb.hwwilsonweb.com/.

2. Miller, Karen J., Eugene P. Kennedy, and Vernon N. Reinhold. "Osmotic adaptation by gram-negative bacteria: possible role for periplasmic oligosaccharides." Science 231 (Jan 3, 1986): 48(4). Student Resource Center - Bronze. Gale. PIEDMONT HIGH SCHOOL. 6 Apr. 2009 <http://find.galegroup.com/ips/start.do?prodId=IPS

3. Campbell, Neil A. “Biology.” Pearson, San Francisco. 2008.

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“Borrowed Photo” Credits

1. http://www.faqs.org/health/Body-by-Design-V2/The-Urinary-System.html

2. http://bio1152.nicerweb.com/Locked/media/ch44/

3. http://www.agen.ufl.edu/%7Echyn/age2062/OnLineBiology/OLBB/www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookglossM.html

4. http://health.allrefer.com/pictures-images/kidney-anatomy.html

5. http://www.nature.com/ki/journal/v63/n4/images/4493564f4.gif 

6. http://home.bway.net/rjnoonan/humans_in_space/nephron.gif 

7. Campbell, Neil A. “Biology.” Pearson, San Francisco. 2008.