excretory system. figure 44.8a most aquatic animals, including most bony fishes mammals, most...
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Excretory System
Figure 44.8a
Most aquaticanimals, includingmost bony fishes
Mammals, mostamphibians, sharks,
some bony fishes
Many reptiles(including birds),
insects, land snails
Ammonia Urea Uric acid
Figure 44.2
Selectively permeablemembrane
Solutes Water
Net water flow
Hyperosmotic side: Hypoosmotic side:
Lower free H2Oconcentration
•
Higher soluteconcentration
•
Higher free H2Oconcentration
•
Lower soluteconcentration
•
Figure 44.14b
Kidney Structure
Renalcortex
Renalmedulla
Renal artery
Renal vein
Ureter
Renal pelvis
Figure 44.14d Nephron OrganizationAfferent arteriolefrom renal artery Glomerulus
Bowman’s capsule
Proximaltubule
Peritubularcapillaries
Distaltubule
Efferentarteriolefrom glomerulus
Collectingduct
Branch ofrenal vein
Vasarecta
Descendinglimb
Ascendinglimb
Loopof
Henle
200
m
Blood vessels from a human kidney. Arterioles and peritubular capillaries appear pink; glomeruli appear yellow.
Figure 44.14e
Figure 44.19-2
ThirstHypothalamus
ADH
Pituitarygland
Osmoreceptors inhypothalamus trigger
release of ADH.
STIMULUS:Increase in blood
osmolarity (forinstance, after
sweating profusely)
Homeostasis:Blood osmolarity
(300 mOsm/L)
Drinking reducesblood osmolarity
to set point.
H2O reab-sorption helpsprevent further
osmolarityincrease.
Increasedpermeability
Distaltubule
Collecting duct
Collectingduct
ADHreceptor
COLLECTINGDUCT CELL
LUMEN
Second-messengersignaling molecule
Storagevesicle
Aquaporinwater channel
Exocytosis
H2O
H2O
ADH
cAMP
Figure 44.20
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