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AB120 - Ch.44
Osmoregulation and Excretion
53
Biology
Undergraduate 1
01/28/2010

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Term
osmoregulation
Definition
regulation of solute and water balance
Term
osmolarity
Definition
total solute concetration (mosm/L)
Term
isoosmotic
Definition
solution have same osmolarity
Term
hyperosmotic
Definition
solution having greater osmolarity
Term
hypoosmotic
Definition
solution having lower osmolarity
Term
osmoconformer
Definition
animal does not actively adjust its internal osmolarity
Term
osmosis
Definition
movement of a solvent (as water) through a semipermeable membrane
Term
osmoregulator
Definition
animal that must adjust its internal osmolarity
Term
stenohaline
Definition
animals that cannot tolerate substantial changes in external osmolarity
Term
osmotic gradient
Definition
difference in concentration between two solutions on either side of a semipermeable membrane
Term
euryhaline
Definition
animals that can survive large fluctuation of external osmolarity
Term
transport epithelium
Definition
layer (or layers) of specialized epithelial cells that regulates solute movements
Term
excretion
Definition
(elimination) of waste products of metabolism
Term
ammonia
Definition
excreted by most aquatic animals; must be diluted because it is very toxic; low energy excretion; unsuitable for terrestrial life
Term
urea
Definition
most prevalent; excreted by mammals, adult amphibians, and marine fishes and turtles; much less toxic; conserve water; metabolically expensive
Term
uric acid
Definition
ENERGY EXPENSIVE; associated with animals that lay hard shells; minimal water loss
Term
filtration
Definition
blood is filtered by transport epithelia
Term
filtrate
Definition
aqueous solution in excretory system (the sample)
Term
reabsorption
Definition
selective transport of water and valuable solutes back into blood; majority of solutes will do this;
Term
secretion
Definition
additional solutes (and toxins) are removed from blood and added to filtrate; active process; highly selective
Term
excretion
Definition
elimination of urine; leftover filtrate
Term
prototonephridia
Definition
excretory system found in flatworms
Term
flame bulb
Definition
hollow cell in the excretory system of certain invertebrates, including flatworms and rotifers, containing a tuft of rapidly beating cilia that serve to propel waste products into excretory tubules
Term
metanephridia
Definition
excretory system found in annelids
Term
malpighian tubules
Definition
excretory system of arthropods
Term
nephron
Definition
functional unit of vertebrate kidney (~1million per kidney); tubular component
Term
glomerulus
Definition
ball of capillaries in nephron
Term
Bowman's capsule
Definition
cup-shaped receptacle surrounding glomerulus
Term
podocytes
Definition
functioning as a filter in the nephron (nonselective)
Term
proximal tubule
Definition
initial tube; convoluted and twisted; near to beginning of nepron
Term
loop of Henle
Definition
desceding limb + thin ascending + thick ascending limb
Term
distal tubule
Definition
far tube from beginning of nephron
Term
collecting duct
Definition
where the final filtrate is dumped for elimination
Term
cortical nephrons
Definition
(80% in humans) short loops of Henle
Term
juxtamedullary nephrons
Definition
(20% in humans) long loops of Henle
Term
renal artery
Definition
majory artery that feeds each kidney
Term
afferent arteriole
Definition
to each nephron
Term
efferent arteriole
Definition
from each nephron
Term
peritubular capillaries
Definition
surround proximal and distal tubules
Term
vasa recta
Definition
parallel to loop of Henle
Term
renal vein
Definition
major vein out of kidneys
Term
renal cortex
Definition
outer potion of the vertebrate kidney
Term
renal medulla
Definition
inter potion of the vertebrate kidney, beneath the renal cortex
Term
nephridopores
Definition
the name of the opening of the tubules in flat worms that eliminate unwanted materials
Term
countercurrent multiplication
Definition
longer loops of Henle = more concentrated urine
Term
aquaporins
Definition
water channels required for water to pass through plasma membrane
Term
antiduretic hormone (ADH)
Definition
vasopressin; increases water permeability when elevated; triggered by blood osmolarity; more water is retained
Term
renin-angiotensin-aldosterone system (RAAS)
Definition
triggered by drop in blood pressure, blood volume, or NaCl concentration; angiotensinogen->angiotensin II (by renin)->constriction of arterioles, increase NaCl reabsorption, aldosterone release->increase NaCl reapsorption
Term
atrial natriuretic peptide (ANP)
Definition
(antagonistic to RAAS), triggered by rise in blood pressure or blood volume; excretes more water
Term
angiotensinogen
Definition
inactive enzyme that is catalyzed in the RAAS system that is transformed in to angiotensin II
Term
renin
Definition
the catalyst that turns angiotensinogen into angiotensin II; secreted by the juxtaglomerular apparatus (JGA)
Term
angiotesin II
Definition
increases blood pressure and blood volume by constricting arterioles, increasing NaCl absorption (therefore H2O too), and stimulating release of aldosterone
Term
aldosterone
Definition
increases Na+ (and thus water) reabsorption of distal tubules
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